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Aug 172012
potting soil

Planting media should be “soilless.”

The best media for container gardening are ‘soilless mixes’ or commercial potting soils. These are combinations of peat moss, sand, vermiculite, and perlite that do not contain actual garden soil. Soilless mixes provide distinct advantages over soil with respect to water holding capacity, drainage and disease management. This is very important for sustained growth capacity in the limited space of a container.

Potting soil is most easily purchased in bags if the quantity needed is small. If larger quantities are needed, bulk quantities can be purchased at some nurseries. Another option is to mix your own. There are as many possible combinations of ingredients as there are gardeners, but a simple, effective recipe consists of:

5 gallons of vermiculite, 5 gallons of peat moss, 5 gallons of washed sand, to which is added 1 cup of 10-10-10 or similar fertilizer. This mixture can be adjusted by adding a few gallons of compost or regular garden soil, replacing some of the peat with a bark product, or replacing all or part of the vermiculite with perlite..

Ohio State University has published a container gardening site that includes a detailed discussion of potting soils.

 August 17, 2012
Aug 172012
water can

Water is key to container plant health

Principles for maintaining healthy plants in containers are no different than for plants in a garden. However, in practice, container plants require greater attention to detail. Limited soil volume and potential stress create requirements for frequent irrigation and fertilizer and constant monitoring for pests.


There is no easy way to schedule watering of container plants. During hot weather, irrigation may be needed every day. However, it should be recognized that overwatering of container plants is a more common cause of death than is underwatering. With that said, a rule of thumb is to let the top 1-2 inches of soil completely dry between irrigations. When applying water, add a sufficient quantity to allow some water to drain out the bottom of the pot.


A high level of fertility must be constantly maintained in containers to keep plants healthy and attractive. The two best methods for applying fertilizer are to 1) mix a slow-release granular fertilizer into the top few inches of soil in the spring and again in mid-summer, or 2) use a solution of a complete fertilizer once a week when irrigating the containers.

Pest Control

Many insect pests infest container plants to a greater degree than garden-grown plants, especially spider mites. Diseases also can become problematic, especially if plants are stressed. Plants should be monitored frequently to identify pest problems before damage becomes severe. Pest control methods for container plants are identical to those described in the other places in this web site (annuals, perennials, bulbs, Insect and Disease Pests).

Excellent information on container gardening is provided Chapter 19 of the Idaho Master Gardener Handbook.

Kansas State University provides detailed container garden instruction.

 August 17, 2012
Aug 172012
Revennae grass

Revennae grass serves the role of pampas grass in cold climates. Photo courtesy of Judy Sedbrook

As with any perennial, proper site selection is critical for success with ornamental grasses. Soil preparation in a perennial bed is completed only one time, just prior to planting and must be done properly. First, kill and remove any persistent weeds, especially grasses. Such weeds are difficult to manage once the beds are planted. This may take several months and multiple applications of a systemic herbicide. Except in native naturalized plantings, amend the soil by adding 2-3 inches of well-aged compost or manure. This is especially important in the arid, calcareous soils of southern Idaho. Add the equivalent of 3 lb/1000 sq. ft. of nitrogen in the form of a complete fertilizer, such as 5-10-5.

After amendments are added, the soil should be tilled to a depth of at least 8 inches, leveled, and smoothed (but not packed). Just prior too or after planting, it is a good idea to add two or three inches of mulch (wood chips, bark, etc.) to the soil surface. It may also pay dividends to place some type of edging or border around the bed to slow encroachment of grass or other weeds.

 August 17, 2012
Aug 172012

Proper site selection is critical for success with bulbs. The soil must be well-drained and attention given to proper light conditions (full sun for most bulbs).

Shovels in soil

Bulbs require deeply worked soil

Soil in bulb beds should be heavily amended with organic matter. Well-aged compost works well. Application of organic matter should be followed by deep tillage, at least 12 in. deep. The bed should be leveled and smoothed, but not packed. Just prior to or after planting, it is a good idea to add two or three inches of mulch (wood chips, bark, etc.) to the soil surface. It may also pay dividends to place some type of edging or border around the bed to slow encroachment of grass or other weeds.


Spring flowering bulbs should be planted in the fall. They require a period of cold weather to bloom and because these plants are generally hardy, the best way to provide cold is let them reside in the soil over winter. In Idaho , the best time to spring plant bulbs is late September through mid-October.

Summer flowering bulbs should generally be planted approximately one week after the last frost. To estimate the last frost date in your area, look at the Idaho chart compiled by Ed Hume Seeds. Some bulbs, such as caladiums and begonias will benefit from being started indoors 6-10 weeks before planting outdoors. They should not be taken outside until all danger of frost is past. In much of Idaho , this typically means 2-3 weeks after the last average frost date. Cornell University Suffolk County Extension has compiled a great discussion of planting and managing summer bulbs.

As a general rule, bulbs should be planted two to three times deeper than the top-to-bottom measurement of the bulb itself. Summer flowering bulbs may be exceptions to this rule and planting instructions should be provided on the purchase package. Planting density varies widely according to species and personal preference. Specific instructions for many species are provided in the Dutch Gardens web site. This site also provides pictures, descriptions, and cultivation techniques for many bulbs.

Before planting, an application of fertilizer should be made. Bonemeal or a high phosphate fertilizer should be placed in the planting hole, followed by the addition of a small amount of soil to prevent direct contact of the fertilizer and the bulb, then the bulb planted. This can be followed up with a small amount of a complete fertilizer (equal to 1 to 2 lb nitrogen per 1000 sq. ft.) at the time the plants emerge. Bonemeal should be used with caution around dogs, who are attracted to the scent and may dig up bulbs planted with bone meal.

Additional planting information can be found in sites sponsored by the Rochester Gardening Club and Iowa State University .

Bulbs are planted in the spring (for summer flowering) or fall (for spring flowering). Most bulbs are planted at least 4-8 inches deep, depending on the size. Fertilization at this time is recommended with a product high in phosphorus. Bone meal is an excellent choice,

Another excellent resource is the University of Illinois Bulbs and More web site.

 August 17, 2012
Aug 172012

Bulbs do not require and excessive amount of care, but timing and quantity of inputs are unique relative to other perennials. Here is a guide to care for established bulb gardens.


If not done before planting, it is beneficial to mulch the bulb flower bed before heat of summer sets in. This will keep the soil cool, retain moisture, and help with weed control.


Bulbs require deep watering


Bulbs have a range of water needs, depending on species, but most need soil that is consistently moist. For spring bulbs, except in the case of a very dry spring, irrigation is not usually needed until about the time flower buds appear on the plants. Once started, irrigation will likely be needed until the foliage dies and the bulbs go dormant. Because they are planted deep, bulbs should be irrigated less often and to a greater depth than nearby lawn areas. Summer flowering bulbs will likely need water until first frost.


Bulbs are not considered heavy feeders, but do need an annual application of fertilizer to look their best. Use a complete fertilizer that is relatively high in phosphorus. Apply the equivalent of 2-3 lb nitrogen per 1,000 sq.ft. Timing of application is fairly critical. Bulbs begin growing new roots very early in the spring and need fertility available to start this process. So, the best time to apply fertilizer to spring bulbs is in October or early November. A second option is to apply half the fertilizer in the fall and the other half about the time the plants begin to flower. Summer blooming bulbs do best with fertilizer applied about the time the plants emerge or when they are transplanted outside.

Weed Control

There are no options to completely replace hand weeding in bulbs. Mulching with organic matter or weed barriers will help by blocking germination and growth of weed seed. Perennial weeds that emerge before the bulbs can be sprayed out with a glyphosate product. Grasses in irises and gladiolas can be controlled with a grass herbicide containing sethoxydim. Grass controlling herbicides cannot be used on other bulbs without risk of serious injury.


Some bulb plants, especially summer bulbs, have large flowers and somewhat weak stems. They may need to be tied to stakes or allowed to grow inside a support cage to remain upright and attractive.


Foliage should die naturally before pruning

Post-bloom Care

Immediately after the bloom period, all seed heads should be removed. This not only improves appearance, but allows the plant to direct its energy to producing new and larger bulbs. The foliage of bulb plants should be allowed to die naturally (or at least be yellow and dying before removal). Healthy leaves are essential to the process of growing new bulbs. Over a period of a few years, removing the leaves too early will cause the bulbs to become smaller and decline in vigor.

Many gardeners do not like the look of post-bloom foliage in the garden. The unattractive leaves can be masked by planting other types of flowers in the bulb garden that will take up the slack in bloom time while the bulbs complete their growth and decline.

Over a period of several years, some bulb plants, such as daffodils, tulips, and crocuses will produce many bulbs and become crowded. When severe, this crowding will reduce bloom potential and make blooms smaller. This can be solved by uncovering the bulbs, dividing them into single units, and replanting the largest and healthiest of the bulbs at a more appropriate spacing. Dividing is best done in the fall, the usual time for planting bulbs. However, by fall all sign of foliage is gone and it is hard to identify the location of the bulbs. This can be solved by using small stakes to mark the plants before they die, or as a second best option, by simply dividing in late spring when the foliage has declined but still marks the presence of plants. Bulbs that are freshly dug and divided should be replanted as quickly as possible to prevent damage from drying conditions. Although not considered an option of choice in Idaho , spring bulbs can be harvested after blooming and stored in the refrigerator until being replanted in the fall.

Tender summer bulbs

Tender summer bulbs must be harvested and stored in the fall

In all regions of Idaho , the tender summer bulbs, such as dahlia, canna, tuberous begonia, and gladiolas must be harvested at the end of the growing season and stored indoors. Otherwise, the bulbs will be damaged or killed by freezing soil conditions. At the first sign of frost injury on the foliage, the bulbs should be harvested, cleaned, cured, and stored. Proper storage conditions vary by species. Complete discussion of the harvesting and storing process, including proper storage conditions for common summer bulb plants, can be found in a University of Minnesota document written by Mary Meyer.

The University of Illinois provides more general information on growing bulbs.

Forcing Bulbs

The term forcing refers to growing practices that bring bulb flowers into bloom during the off-season. Typically, this process is used to produce indoor flowers during the winter months. For each species, certain environmental constraints must be met to overcome bulb dormancy and allow growth and bloom. For spring bulbs, this usually means cold storage before planting in a pot. For summer bulbs, it may mean supplying specific requirements of light duration. It is beyond the scope of this discussion to provide specific requirements of all plants, but understand it can be done and seek procedures elsewhere. Information on forcing spring bulbs can be found on the University of Kentucky site.

Insect and Disease Control

It is beyond the scope of this site to provide specific pest management information for the large number of commercially available bulb species. Each has unique problems that may be more or less serious. However, there are many pests that are common and infest many types of plants. Diagnostic and simple control information will be given below for these common pests. For detailed information on control of insects and diseases, as well as information of other pests, see the Insect and Disease Pests section of this site.

Insect Problems

Aphids: Also known as plant lice. Small, soft-bodied, sucking insects that cluster on the stems or underside of leaves. Aphids are usually wingless and green, brown, or black in color. Symptoms of infested plants include distorted or curled leaves, presence of sticky sap (honeydew) on the infested surfaces, and misshapen new growth.

Aphids can be controlled with the use of insecticidal soap or a registered insecticide. A strong stream of water directed at the infected plants may knock them from the plant. Many beneficial insects feed on aphids and if an infestation is not too severe, it may be appropriate to be patient and let nature take its course.

Spider Mites: Not actually insects, these miniscule pests are actually related to spiders. They spin protective webs on the underside of leaves and feed by sucking juice from the leaves. Symptoms include color mottling that, at a distance, may appear as a general yellowing of older leaves. Webbing will be presence on the underside of infested leaves. The mites, to small to be easily visible, can be detected by shaking a leaf over piece of clean white paper.

Spider mites prefer dry, dusty environments. Sprinkler irrigation or routine washing of leaves with water usually keep them at bay. A severe infestation may require the use of a registered miticide. Most common insecticides are ineffective against spider mites.


Slugs can damage many bulb flowers

Slugs and Snails: Prefer damp soil and humid conditions. Slugs and snails often hide during the day and feed at night. Symptoms include chewed leafs and glistening slime trails on plant surfaces.

Control snails and slugs with baits.

Thrips: Damage is cause by the larva of this small, four-winged insect. Thrips reside on the underside of leaves and use their rasping mouthparts to scrape away the surface of the leaf after which they feed on the sap. Symptoms appear as white streaks and blotches, more prominent on the underside of the leaf.

A light infestation does little permanent damage to the plant and can be ignored. A heavy infestation will likely require the use of a registered insecticide.

Disease Problems

Root and Bulb Rots: Are caused by the penicillium (blue mold) and Fusarium fungi and the soft rot bacteria that live in the soil. These organisms are worse problems on bulbs that are harvested and stored than on those that are left in the soil over winter. Infected bulbs become soft, pink, or mushy and often have an offensive odor.

Control measures include careful harvesting to prevent injury that provides a point of entry for rot organisms. Infected bulbs should immediately be eliminated.

grey mold on peonies

Grey Mold affects many bulb plants, including peony

Grey Mold or Botrytis: Is caused by a fungus that overwinters in the soil. It infects plant stems that touch moist soil surfaces and splashed onto leafs with rain or irrigation water. Symptoms include water-soaked spots on the leaves that become a slimy, grey mold. Infected tissue quickly collapses and dies.

Control includes removal of infected tissue, both live and dead. In severe cases it may be necessary to apply a preventative fungicide.

Daffodils with virus

Bulb can be affected by chronic viruses

Virus: Not technically alive, viruses are small, disruptive pieces of genetic material that disrupt plant function. Symptoms vary widely and usually include some combination of stunting, yellowing, mottling, or leaf and stem distortion. Viruses are a particularly severe problem on bulbs and other perennials because their long life span and lack of seed propagation create many opportunities for chronic infection.

There are no control measures for viruses other than using resistant varieties or controlling the organisms (usually insects) that transfer them from one plant to another. Prevention involves removing and destroying any infected plants.

Information on control of garden insects and diseases common to Idaho can be found in the online Idaho Master Gardener Handbook.

See specific information on controlling bulb diseases and insects at the University of Connecticut web site.


Ornamental onions

Ornamental onions are eye-catching summer bulbs

 August 17, 2012
Aug 162012

transplanting a seedlingSoil preparation is critical to success with annuals. Proper site and soil preparation will ensure a healthy environment for annual flowers. First, make sure the site has good quality topsoil. This may require addition of topsoil, particularly in new home sites. Amend the soil by adding 3-5 inches of well-aged compost or manure. This is especially important in the arid, calcareous soils of southern Idaho. Add the equivalent of 5 lb/1000 sq. ft. of nitrogen in the form of a complete fertilizer, such as 5-10-5. The fertilizer choice should be high in phosphorus and should preferably include sulfur. After amendments are added, the soil should be tilled to a depth of at least 8 inches, leveled, and smoothed (but not packed). Just prior too or after planting, it is a good idea to add two or three inches of mulch (wood chips, bark, etc.) to the soil surface.

 August 16, 2012
Aug 162012

Once established, many annual plants are relatively carefree. However, as is true of all plants, some tender loving care is needed to keep them healthy and attractive.


Mulch provides many benefits


If not done before planting, it is beneficial to mulch the flower bed before heat of summer sets in. This will keep the soil cool, retain moisture, and help with weed control.


Annual flowers use about the same amount of water as does lawn, equal to about ¼ in. per day during July and August. In most Idaho soils, this means approximately 1 in. of water should be applied every 4 to 5 days. In sandy soils, less water should be applied on a more frequent basis. The amount of water applied should be cut back during the cooler spring months, the late fall, and during those infrequent periods of rain. The simplest method of judging water need is to wait between irrigations for the top 1-2 in. of soil to dry.


In most loam soils, preplant fertilization may be adequate to provide basic nutrient needs for annual plants. However, under conditions of sandy soils or long growing season, there may be benefit in adding a small amount (equivalent of 2-3 lb nitrogen per 1000 sq. ft.) of a fertilizer that is high in nitrogen. Sprinkle the fertilizer on the soil surface and water it in. Make the application in late June or about the time the flowers reach peak bloom.


Some annuals need a little attention to appearance to remain attractive. Plants that look thin and leggy can be forced to produce more lateral growth by shearing or pinching off the growing point of each stem. Plants that fall down or become floppy may need to be staked or interplanted with stiffer, more upright types of plants. Many annuals either do not shed dead flowers or produce seed heads, thus reducing production of additional flowers and making the plants less attractive as the summer progresses. This can be solved by occasionally removing the dead flowers, a practice called “deadheading”.

seed head

Removing old seed heads encourages flowering

Weed Control

There are no control options that completely replace hand weeding in annuals. Mulching with organic matter or weed barriers will help by blocking germination and growth of weed seed. Some partially effective herbicides are available to help with weed control in annuals. All of these must be applied after the flowers emerge or are transplanted, but before the weeds emerge. See your county agent or local nurseryman for information on products available.

Disease and Insect Control

With over a hundred species of annual flowers commonly available, it is beyond the scope of this site to provide specific pest management information for each one. However, there are many pests that are common and infest many types of plants. We have compiled information on the most common of these in our pages on insect and disease problems.

For more detail on control of insects and diseases, as well as information of other pests not covered in the sections above, see the Insect and Disease Pests section of this site.

 August 16, 2012
Aug 162012

Following proper guidelines for mowing, fertilization and irrigation will help keep thatch accumulation to a minimum. Mow at the proper mowing heights and follow the 1/3 rule to keep the grass from becoming stressed. Fertilization to avoid excessive growth also is important in preventing thatch buildup. Never apply more than 1 lb of nitrogen per 1000 ft² at any one time, especially in the spring when the grass is growing vigorously. Irrigate to encourage deep rooting will also keep thatch to a minimum. Remember to water ‘deep and infrequent’ for best results.

 August 16, 2012
Aug 162012

Billbugs are perhaps the most common insect affecting home lawns in Idaho. The adults, which are about 1/4 inch long, can be seen in the spring, walking along sidewalks especially on the southern sides of buildings.

Adult bluegrass billbug

Adult bluegrass billbug crawling on a sidewalk. (Photo courtesy: H.D. Niemczyk, Ohio State University)

The adults are a black weevil, have a long snout and will play dead when disturbed. The adults do very little damage, but in the larval stage billbugs eat grass stems and roots. Adults become active when soil temperatures reach 55º F, usually early to mid-May. The larvae are small (1/8 – 1/4 inch long), white, legless grubs with a brown head.

Billbug Larva and adult.

Billbug Larva (right) and adult. (Photo courtesy: H.D. Niemczyk, Ohio State University)

Lawns damaged by billbugs look like they are drought stressed because the grass blades are basically severed from the roots. Grass blades can be easily pulled out by hand with a light tug. A healthy, vigorously growing lawn will recover from moderate billbug damage and symptoms may go unnoticed. However, under-fertilized lawns or lawns that are otherwise stressed will be more susceptible to billbug damage.

Control. If you have areas with known billbug problems, control measures should be targeted against the adults in the spring when they are active and seen crawling along sidewalks or other exposed areas. Waiting until damage is visible may be too late since the damage has already been done. If targeting larvae, good coverage and movement of the insecticide past the thatch layer are very important. Since adults are on the surface of the turf, they are more easily contacted with insecticides.

 August 16, 2012
Aug 162012

A properly fertilized lawn will not only look nice, but will be more resistant to diseases like leaf rust and will also fend off weeds by out-competing them. Three basic questions to ask when it comes to lawn fertilization are: how much should I apply, when should I apply it and what kind of fertilizer should I use? Remember to consider the desired quality level you want for your lawn when considering these questions. If you want a ‘low maintenance’ lawn, you need to be sure you have a grass species that can tolerate low fertility and minimal irrigation.

 August 16, 2012
Aug 162012

It is important to understand the main nutrients that lawn grasses require for adequate growth.

Nitrogen is perhaps the most important nutrient as it helps the grass produce green, healthy leaves. Since leaves are the energy-making factories of the plant, it is important that enough nitrogen be provided to maximize their energy making capabilities without causing an over production of leaves.

Phosphorus is important for strong root growth and is very important during establishment. Since phosphorus does not move readily in the soil and new grass seedlings have limited root systems, providing some phosphorus fertilizer during establishment is very important. Mature lawns have very fibrous root systems and are much more adept at mining phosphorus from the soil. Generally, unless very deficient, fertilizers with low percentages of phosphorus are used for lawns.

Potassium is very important for lawns and helps grasses respond to heat and drought stress. Although deficiencies in potassium are difficult to detect, the importance of potassium in stress management should not be overlooked. Unless a soil test reveals that potassium is very abundant, fertilizers with percentages of potassium similar to nitrogen should be used.

Iron is another nutrient that is important, especially in southern Idaho soils. The high pH soils of southern Idaho tie up iron making it unavailable to the plant causing it to become yellow (iron cholorosis). Iro- containing fertilizers can help alleviate iron chlorosis, but make sure of the type of iron you are buying. Iron in the forms of ferrous sulfate or iron sulfate are absorbed by the leaves. If washed into the soil, the iron quickly changes form and becomes unavailable to the plant. Iron in the form of iron chelate (Fe-DTPA, Fe-EDTA, Fe-EDDHA, and Fe-HEDTA), are more effective as soil applied fertilizers. Iron in this form is available to the plant even when in contact with the soil and the effect is much longer lasting than the foliar-absorbed iron fertilizers.

 August 16, 2012
Aug 162012

A general recommendation for cool-season grasses is a range from 0.5 to 5 lbs of nitrogen (N) per 1000 ft2 per season depending on the desired level of quality. Low input lawns with tall fescue or fine fescue will only require about 2 lbs N per 1000 ft2 per season or less, while low input lawns of Kentucky bluegrass and/or perennial ryegrass will require approximately 3 lbs N per 1000 ft2 per season. Medium to high input lawns of Kentucky bluegrass and perennial ryegrass will require 3 – 5 lbs N per 1000 ft2 .

 August 16, 2012
Aug 162012

To understand the timing of lawn fertilization, it is important to understand the seasonal growth pattern of a grass plant. In the spring, grasses are coming out of winter dormancy and begin rapid growth using stored energy reserves from last year. Grasses that are over-fertilized with nitrogen in the spring will spend too much of those energy reserves on leaf growth and will not have enough left over to take them through summer’s heat and drought stress. All that is needed in the spring is to supply the grass with just enough nitrogen fertilizer to prevent it from becoming chlorotic (very light green to yellow in color).

As temperatures rise in the summer, leaf and root growth start to slow. Over-fertilization at this time could be very detrimental to the health of the grass and even cause areas to die. Avoid fertilizing during the summer except to prevent chlorosis. Very light applications and use of a slo- release fertilizer will help keep the grass green in the summer without burning or damaging the lawn.

As temperatures cool and hours of light per day diminishes in late summer to early fall, grasses begin preparing for winter by sending their energy reserves to their rhizomes and roots. A fertilizer application at this time will help the plant maximize energy production and most of the engergy will be sent to storage instead of being used for leaf growth.

Table 1 gives recommendations for various grasses at various times of the year. Keep in mind that the March application may be omitted if green-up is satisfactory and a late fall application was made the previous year. In this case, a single application of 1 lb N per 1000 ft2 can be made. Use slow release fertilizers for a late fall application and on sandy soils throughout the year to reduce nitrogen leaching. Additionally, if you are using a mulching mower or otherwise returning clippings to the lawn, you may be able to cut back the nitrogen by about one fourth.

Table 1. Nitrogen fertilization schedule for home lawns.  (Adapted from Colorado State University lawn fertilization extension fact sheet).

Grass Type¹ & Maintenance Level² Mid March – Mid April Early May – Early June July – Early August Mid August – Mid September Early October – Early November
Rates are in lbs of N per 1000 ft2
KBG – Low 1/2 1/2 none 1 1 (optional)
KBG – Med – High 1/2 – 1 1 none 1 1 – 2 (2 is optional)
Tall fescue – Low 1/2 1/2 none 1 1 (optional)
Tall fescue – Med – High 1/2 1 none 1 1 (optional)
Fine fescue – Low 1/2 1/2 none 1/2 none
Fine fescue – Med 1/2 1 none 1 none
Buffalograss none 1/2 – 1 1/2 – 1 none none
¹Grass Type: KBG = Kentucky bluegrass
²Maintenance Level: Low = low maintenance, Med = medium, High = high maintenance
 August 16, 2012
Aug 162012

There are many types of fertilizer available for purchase, and it can be quite confusing trying to choose the correct one. Understanding the nutrient requirements of the grass as described above will help narrow the choices. Understanding the different types of fertilizers, will help narrow the choices even further.

Fertilizers can be divided into two major groups, fast release and slow release. This refers to how quickly the nitrogen is released and made available to the plant. You may also have heard about organic vs. inorganic fertilizers. This refers to the chemical composition of the fertilizer. It is important to understand that the term “organic” means the fertilizer contains carbon in the chemical structure. Organic fertilizers include natural materials such as sewage-based products like Milorganite®, animal by-products like manures and bone meals, and plant by-products like corn gluten meal. There are also synthetic organics like urea which is very common in the agricultural industry, but less so in the turf industry because of its very fast release and high burn properties. There are, however, also many forms of urea that have been developed to slow its release and lower its burn potential.

Fast-Release Fertilizers

Fast-release fertilizers are quickly released into the soil and available for uptake by the plant. The advantages of these materials are that they are relatively inexpensive, are not dependent on temperature for release and give the grass a quick response. The disadvantages of fast-release fertilizers are that they are more likely to burn the turf if applied incorrectly (during hot periods or at too high of a rate), the response is generally short lived, and because of their water solubility they are more likely to leach through sandy soils or runoff of compacted soils. Several light applications can compensate for the quick, short-lived response, but this requires more labor.

Slow-Release Fertilizers

Slow-release fertilizers cause a more uniform color and growth response over a longer period of time than the fast-release fertilizers. They are also less likely burn the grass. Some products will release nitrogen into the soil slowly over several weeks or even months. All the natural products like manures, bone meals, etc. are slo- release fertilizers and require soil microbes to release the nitrogen to make it available to the plant. When applied to cool soil temperatures, below 50° F, the grass may not respond at all to the application. Most of the natural slow-release fertilizers are quite low in nitrogen content so it will take more product to apply the same rate of actual nitrogen as it would with a synthetic fertilizer with a higher nitrogen content. Other types of slow-release fertilizers include sulfur-coated urea, polycoated urea and other urea based products. These products tend to be more expensive, but provide a good uniform turf response.

 August 16, 2012
Aug 162012
Fertilizer stains on sidewalk

Stains on sidewalk caused by mis-application of fertilizer particles. (Photo courtesy: A.J. Koski, Colorado State University)

Drop spreaders and rotary spreaders are available for fertilizer applications on home lawns. Both can do an effective job if used correctly. Drop spreaders, as the name implies, drops the fertilizer material directly from the spreader onto the lawn placing the fertilizer precisely in the location desired. Drop spreaders take longer because you must cover every square inch with the spreader.

With rotary spreaders, the fertilizer material is spun out over a large area.  A lawn can be fertilized more quickly with a rotary spreader because of the area covered in one pass, but some fertilizer invariably gets thrown where it is not wanted such as sidewalks and streets. Make sure to sweep up fertilizer off sidewalks as the prills can cause stains and can wash into storm drains.

Misapplication of fertilizer

Misapplication of fertilizer using a drop spreader. (Photo courtesy: Iowa State University)

Regardless of the type of spreader used, it is a good practice to cut the application rate in half and apply the fertilizer in two directions to avoid stripping patterns.

 August 16, 2012
Aug 162012

Low maintenance can have several meanings. To some people, low maintenance means no maintenance at all. In this case the grass is left to grow much like a meadow or grass along a highway, etc. To others, low maintenance means little if any fertilization, minimal irrigation, infrequent mowing, and pest control only if absolutely necessary. The latter may be what most people would prefer in a home lawn as long as it results in acceptable quality. It is important to understand that the quality expectations of lo- maintenance lawns should not be very high since minimal inputs will result in a turf of minimal quality.

 August 16, 2012
Aug 142012

Under natural forest conditions, the annual decomposition of leaves, needles and twigs provide a fresh resource of minerals for tree and shrub use. Landscape trees grown in lawns and driveways usually do not have this nutrient source and are in need of additional minerals since landscape debris is routinely hauled away.

Sixteen chemical elements are known to be important to a plant’s growth and survival. The first of these are carbon (C), hydrogen (H) and oxygen (O), which plants acquire in sufficient quantities from the air and water. The other 13 mineral nutrients, are acquired by plant roots, which absorb soil minerals dissolved in water. The required mineral nutrients are divided into two groups: macronutrients and micronutrients.

The primary macronutrients are nitrogen (N), phosphorus (P), and potassium (K). These major nutrients are usually lacking from the soil first because plants use large amounts for their growth and survival. The secondary macronutrients are calcium (Ca), magnesium (Mg), and sulfur (S). Fertilization with these nutrients is not always needed.

Micronutrients are nutrients needed needed in only very small quantities . The micronutrients are boron (B), copper (Cu), iron (Fe), chloride (Cl), manganese (Mn), molybdenum (Mo) and zinc (Zn). Southern Idaho soils can be deficient in S, Fe, Mn, and Zn.

 August 14, 2012
Aug 142012

The type of soil that a tree or shrub grows in can affect its nutrient needs. Soil texture and soil structure influence the amount of water, air, and nutrients held in the soil for plant use. Clay soils can be nutrient rich, but have a large amount of fine particles that tend to compact and restrict water and air movement. Sandy soils drain well, but contain many coarse particles that have little capacity for storing water, air and nutrients. Organic material can be thoroughly mixed into soils with high clay or sand contents to help improve soil structure. Repeated applications may be needed depending on the amount applied and the stage of decomposition or type of organic matter used. Organic material should be mixed into the soil up to several years before trees are installed to obtain maximum benefit.

 August 14, 2012
Aug 142012

No single symptom tells you that trees or shrubs need additional fertilization. Some nutrient deficiency symptoms can be similar to symptoms of cultural problems or diseases. Slow growth rate, small leaves, fewer flowers, smaller fruit, and pale green or yellow (chlorotic) foliage with mottling between the leaf veins may all be signs of nutrient deficiency.

Two methods of determining nutrient deficiencies include:

Soil Testing

Advantages – provides soil pH, levels of K, P, organic matter content and minor nutrients such as iron or zinc.
Disadvantage – does not provide reliable information on N because N is rapidly lost through leaching or removed by plants

Plant Analysis

There are two methods of determining nutrient deficiencies through plant analysis:

Visual symptoms – include length of shoot growth, leaf color, leaf size, and color pattern and timing of leaf drop

Advantages – N and Fe are often the easiest visual symptoms to identify
Disadvantage- symptoms can be deceiving and/or nonspecific

Foliar tissue analysis – provides the concentrations of specific elements in plant foliage (usually leaves)

Advantages – when combined with soil tests it can provide a good picture of nutrient problem(s) – deficiency or toxicity
Disadvantage- nutritional needs for many landscape plants is unknown

 August 14, 2012
Aug 142012

Trees should be fertilized in early spring or mid-fall as long as the soil temperature is above 40º F two inches below the soil surface. Soil should also be moist. Avoid fertilizing in late summer and early fall as a nutrient application at this time could cause unwanted succulent growth that may fail to harden off before fall frosts hit.

Fertilizer Application Methods

Broadcast or topdress – fertilizer is added directly to the soil surface. This method is good for N, which moves readily through the soil, but poor for P and K that move slowly through the soil. Fertilizer should be applied to the drip line and at several foot intervals out from the drip line for mature trees.

Soil incorporated – dry or liquid fertilizer is added to holes in the soil beneath the canopy and extended beyond the drip line and provide a long lasting effect. Holes should be up to 12 inches deep and 1 to 2 inches in diameter and made in concentric circles 2 feet apart around the tree trunk with the first circle no closer than 3 feet from the trunk.

Foliar sprays – best for supply nutrients for plant use in only trace amounts, such as Zn, Mn and Fe.

Tree spikes are a dry soil injection method, with a hardened column or cylinder of fertilizer hammered into the soil.

Controlled release pellets are typically broadcast on the soil surface, but they can also be placed in holes augured into the soil.

Tree spikes and slow release pellets may delay the development of winter hardiness so it is best to use them in late fall or early spring.

 August 14, 2012
Aug 142012

Recommended rates of fertilizer are calculated using the ground area under the tree canopy. The amount of fertilizer to add depends on the fertilizer composition and is usually calculated using the desired N rates. Nitrogen rates range from 0.2 to 0.4 pounds per 100 ft². Excess nitrogen can be detrimental to plant growth.

Quantities of common fertilizers, incorporated into the soil, needed to provide equivalent amounts of N.
Applications rates expressed pounds of fertilizer material per 100 ft² of ground area.
Fertilizer Rate
Fertilizer analysis
0.4 lb N per 100 ft²
0.25 lb N per 100 ft²
20 lbs
12.5 lbs

from 1997 Bulletin CIS 1068. Fertilizing Landscape Trees

Sample Fertilizer Application Problem

If a 10-year-old tree has a canopy that is 20 feet wide, a trunk that is 5 inches in diameter, and roots that extend 35 feet from (one side of) the trunk, how much 18-6-12 fertilizer should be applied via the broadcast method? Use a rate of 3.5 lb. of nitrogen (N)/1000 ft²

First, figure the surface area occupied by the tree’s roots. Area =π*r² where π = 3.14 and r = 35 ft.
= 3.14 x 352
= 3846.5 ft2

Second, calculate the number of pounds of nitrogen needed to cover the root zone.
Pounds of Nitrogen = 3.5 lb. N x 3846.5 ft²
Needed 1000 ft²
= 13.5 lb. N

Third, calculate the number of pounds of fertilizer needed to cover the root zone.
1. Important Relationship
Pounds of Fertilizer x Percent Nutrient = Pounds of Nutrient

2. Calculation for
Pounds of Fertilizer 13.5 lb. N
Needed    = 0.18 N     = 75 lb

 August 14, 2012
Aug 142012

2001 CIS 757 Fertilizer Placement

1997 CIS 1068 Fertilizing Landscape Trees

2004 CIS 1124 Nutrients Plants Require for Growth

2000 CIS 815 Northern Idaho Fertilizer Guide: Blueberries, Raspberries, and Strawberries

1994 PNW 121 Nutrient Disorders in Tree Fruits

1997 CIS 1066 Composting at Home

Other websites that present fertilizing information for trees and shrubs are:

Texas A&M:

Ohio State University

University of Massachusetts
Fertilizing Trees and Shrubs

 August 14, 2012
Aug 102012

Proper soil preparation provides the basis for good seed germination and growth of garden crops. The steps of soil preparation include testing, amending, and tilling.

Testing the Soil

Contact your local County Extension Office to get instructions and sample bags for testing your garden soil. Soil tests are especially critical in a new garden plot but soil should be analyzed at least once every 3 years because conditions do not remain static. The soil test will tell you how much organic matter and fertilizer is needed. To get a relibale soil test, you first need to take a proper sample.

Rows of vegetables growingAmending with Organic Matter

Organic matter improves soil structure, increases water-holding capacity, improves fertility, and reduces problems with soil diseases. There is no replacement for organic matter in improving soil health and providing good growing conditions for vegetables.

Organic matter can be added in the form of plant waste (such as leaves or lawn clippings), composts, green manures, or aged animal manures. It is necessary to consistently  add organic matter (every year or two) because it rapidly breaks down in the soil.

Using compost is a preferred method of adding organic matter to the soil. Apply organic matter to the garden area by spreading a layer of compost 3 to 6 inches deep on the soil surface and tilling to a depth of 10 to 12 inches, if possible with available equipment.

Another method of adding organic matter to soil is to use green manures, which are any living plant material that is mixed with the soil while still green. Green manure crops include such crops as, for example, wheat, oats, clover, mustard and vetch. Grow the green manure in the part of the garden where you will later chop it while it is still green and immediately till into the soil.

Animal manures are best applied in the fall so they have time to completely decompose and salts can partially leach out of the root zone before spring planting. It is best to use animal manures that have been aged for one or two years before applying to a garden, or used composted manure.

To make your own compost, see Composting at Home for a detailed discussion of how to do this.


In this brief format, it impossible to provide fertilizer application recommendations that will apply to every gardening situation. But, whether you prefer traditional or organic methods, some concepts are universal. For one, nothing can replace a soil test for providing the information required to make appropriate fertilizer application decisions. Two, for vegetable gardens, additions of nutrients in some form will be required to consistently grow a good crop. Knowing the amount of fertilizer elements required will make it easier to choose an appropriate product to apply.

Generally, for most Idaho soils, a fertilizer that is relatively high in nitrogen and phosphorus, contains a moderate amount of potassium, and possibly some sulfur will work reasonably well. Follow the fertilizer label directions or contact your local County Extension Office about application rates and methods. Also, UI bulletin, Using Soil Test Results for Garden Fertilization, contains information on interpreting a soil test and how to determine the quantity of fertilizer product to apply.

Fertilizer requirements for vegetable crops vary widely, which complicates fertilizer application decisions. Some crops, such as peas and beets need very little fertilizer. Most long-season crops, such as corn and melons require fairly large amounts (see accompanying table).

Low nutrient-using crops High nutrient-using crops
Bean Broccoli
Beet Cabbage
Carrot Cauliflower
Chard Celery
Lettuce Collard
Parsnip Corn
Peas Cucumber
Potato, early-harvested Eggplant
Radish Kohlrabi
Rutabaga Leek
Spinach Melon
Tomato, short-season areas Onion
Turnip Pepper
Potato, late-harvested
Tomato, long-season areas


Deciding how to fertilize a vegetable garden should take into account the fertilizer amounts needed by “low-nutrient using” crops vs. “high nutrient-using” ones. If you are planting a garden for the first time, it is almost essential to have a soil test so you know the nutrient status of the soil to help determine how much, if any, fertilizer to apply.

If you have been growing a garden for several years in the same location and have been reasonably satisfied with the production, a soil test may not be essential. However, a yearly application of fertilizer is still likely needed. Using a complete fertilizer product, fertilize your garden with 2 to 3 lb N per 1000 ft2 and immediately till it into the soil at the beginning of the season just prior to planting. This amount should be adequate for the low-nutrient using crops. Then after the plants are up and growing, apply an additional 2 to 3 lb N per 1000 ft2 alongside the row—oftentimes referred to as a “sidedress” application—and water into the soil. For this application, you can use a product that is high in N and low in other nutrients. Use UI bulletin, Using Soil Test Results for Garden Fertilization, to determine actual amounts of fertilizer product to apply depending on the nutrient content of the product purchased.

Sandy garden soils, which do not hold nutrients as well as clay, silt, clay loam, silt loam, and other non-sandy soils, require some modification of the above fertilizer application practices. Only part of the total applied fertilizer should be put down before planting. The rest should be applied in small increments during the growing season. This provides the plants with the required nutrients while reducing losses due to leaching. A soil test will help you determine your soil texture.


The final step in soil preparation is tillage. Ideally, soil should be tilled to a depth of at least 10 inches. This can be very difficult with small garden equipment. If larger equipment cannot be used, it may be beneficial to occasionally fracture the soil to a greater depth by pushing a long-tine garden fork deep into the ground and pulling the handle backward to break up the hard lower layers.

It is important to avoid working soil when it is too wet. This is espcecially true for non-sandy texture soil. Working wet soil breaks down the soil structure causing it to become cloddy and hard. The negative impact of tilling wet soil may last for years. To determine if the soil is dry enough to work (till), take a handful and squeeze it tightly into a ball. If the ball breaks into granular pieces when pressed lightly between your fingers, it is dry enough to work. If the ball remains intact and feels sticky when you squeeze it, wait a few days before scheduling tillage operations.

For more information about soils, soil preparation, and fertilizers, study the Idaho Master Gardener Handbook, Chapter 5: Soils and Fertilizers.

 August 10, 2012
Aug 102012

Blueberries are among the most popular fruits for home and market gardening. Both highbush and lowbush blueberries are native to North America and are used fresh or processed into jams, syrups, compotes, fruit leathers, and pastries. Blueberries are firm and hold their quality well both on the bush and in refrigeration. The fruits are easy to freeze and retain their quality when frozen. Blueberry crops can be harvested two to three years after planting, and reach maximum production in six to eight years. Several types of blueberries are available to gardeners. In Idaho, select varieties adapted to USDA Plant Hardiness Zones 4-6. As a general rule, for long-lived plants like blueberries, select varieties one, or preferably two, zones hardier than your location.

Besides producing fruit, blueberries are attractive in landscapes. The compact bushes are easy to prune and produce brilliant orange to red foliage in autumn. The fruit attracts birds and other animals, making blueberries valuable in wildlife-attracting landscapes. Depending on the variety, mature bushes range from eighteen inches to ten feet in height.

Download our free how-to guide!
Growing Blueberries in the Inland Northwest and Intermountain West


Expected yield:

  • Half-highs 1 to 3 pounds per bush
  • Highbush 8 to 20 pounds per bush

Age to maturity: 6 to 8 years after planting
Productive life: more than 50 years
Hardiness: -15 to -30°F, depending on variety
Optimal pH: 4.2 to 5.2
Exposure: full sun
Plant spacing:

  • Lowbush: 1 foot between plants
  • Half-highs: 2 to 3 feet apart in rows 6 to 8 feet apart
  • Highbush: 4 to 5 feet apart in rows 8 to 10 feet apart
Selecting a Site

Blueberries require acid soils, which greatly limits where they can be grown in Idaho. A soil pH between 4.2 and 5.2 is ideal (pH 7.0 is neutral). Blueberries can be grown, with some challenges, on sites where the pH is as high as 6.0. Blueberries suffer from iron chlorosis on soils with pH values above 6.0 that are common in southern Idaho and scattered throughout the state.

Soils having pH values between 5.5 and 6.0 can be acidified by incorporating sulfur into the soil one or two years before planting blueberries. Soil acidification is not cost effective for large sites or when soil pH values are above 7.0. For small scale production on sites with heavy soils, poor drainage, or alkaline soils, blueberries can be grown in raised beds or containers filled with potting mixes or amended soil.

Sites with cool, moist, well drained loamy sand, sandy loam, and loam soils containing around 3% or more organic matter are best for blueberries. Coarser soils dry out too easily and clay soils inhibit root growth and encourage root rot. Production on silt loam soils is possible, but can be challenging due to poor water drainage. Muck soils and boggy areas are unsuitable for blueberries unless you can create raised beds at least 14 inches above the soil surface. On some sites, increasing soil drainage with buried drainage tiles can improve blueberry production.

While blueberries survive in partial shade, you need full sun exposure to develop good fruit flavor and maintain high yields. Blueberries grown in the shade become tall, spindly, and unproductive, creating bushes that are unattractive and do not tolerate snow loads well.


Blueberries are among the most cold hardy fruits, but there are differences in varieties. The most cold hardy blueberries tolerate temperatures of -35°F or below, and many varieties survive temperatures between -20 and -25°F. Rabbiteye and southern highbush blueberries are not reliably cold hardy in Idaho.

 August 10, 2012
Aug 102012

Fruit trees need regular fertilization to remain healthy and productive. How much fertilizer to add depends on the nutrients already available in the soil and the size of the trees. Home gardeners tend to over fertilize their trees, which delays or reduces blossom formation, produces poor yields and fruit quality, and results in vigorous growth of branches and leaves and increased pruning.

Large trees, such as apples on seedling rootstocks, require more nutrients than dwarf trees. Commercial fruit growers have laboratories analyze the leaves in mid summer to determine the nutrient status of the tree. For home gardens, start with the amounts in Table 1 below and watch your trees carefully. If a tree that is old enough to bear a crop produces lush shoots and dark green leaves but few blossoms, you are applying too much nitrogen and/or pruning off too much wood. If growth is slow, stunted, or yellowish, add more nitrogen. Apply fertilizers from early spring through the end of June.

Nitrogen Source Nitrogen Content (%) Planting Year Young Trees (rate per year since planting) Mature Trees (six years or more from planting) (lb)
10-10-10 10 0 6 oz 2
16-16-16 16 0 4 oz 1.5
21-0-0 (ammonium sulfate) 21 0 3 oz 1
Dry manure (other then poultry) 1-2 0 3 lbs 15
Dry poultry manure 3-5 0 1 lb 5

 August 10, 2012
Aug 102012

When it comes time to plant a fruit tree, patience pays for itself many times over. Most of the problems we see with tree fruits come from two sources: failing to select appropriate crops for a site and failing to prepare the site before planting. We dealt with crop selection in Tree Fruits: Crops to Grow. Now let’s consider site preparation.

 August 10, 2012
Aug 092012

There is a little nip in the air, indicating the approach of fall. This means its time to begin winter preparations for your yard and garden. In this process, the lawn sometimes gets ignored because it stops growing and seems to present few demands. However, fall is a key time of the year in lawn growth, and you can have a definite impact on how it looks next spring if you take time to complete a few simple tasks.

Wishing wellCleaning up leaves is more than making the lawn look nice. If left on the ground during the winter, leaves become wet, mat down, and smother the grass during the winter. Grass does not completely stop growing, even in the dead of winter. As it grows, grass needs to breath and matted down leaves reduces air flow. Leaves also cause quite a bit of shading during the fall and early winter before snowfall when the grass is trying to store up energy. Just as chipmunks store food underground for the winter, grass uses sunlight to make food, which it stores in its stems growing underground. If you have just a few leaves and a mulching mower, mulching the leaves and letting them filter into the grass is fine as long as they are not too thick.

Speaking of mowing, it is a good idea to continue mowing your lawn well into October and maybe even into November. These late mowings will not only help chop up any leaves you may have missed, but more importantly, will help prevent winter diseases. You may have heard the advice to lower the mowing height a notch or two on your last mowing. This can help alleviate disease, but be careful not to overdo it. You are better off to leave the mowing height the same, but mow more often into late fall instead.

Lawn fertilizerFertilizing during late fall also is a good idea since the grass, as we mentioned above, is still growing underground, even though leaf growth has slowed considerably or stopped. Since the underground part of grass is what allows it to make it through the cold winter and green up in the spring, a light late fall application is a good idea. Again, be careful not to overdo it. Apply no more than 1 lb of nitrogen (N) per 1000 ft2.

If you have an automatic irrigation system and have not touched the timer since the summer months, now is the time to do so. Grass uses much less water in the fall than during the heat of the summer, less than half as much. That means you may need to irrigate your lawn only about every 10 days depending on soil type. Depending on your location, you may want to irrigate your lawn until the end of October or even into the second week of November. In colder areas of Idaho, freezing temperatures may dictate stopping irrigation before the end of October. A final deep watering just before you winterize your irrigation system is a good idea. This will help prevent winter desiccation damage to your lawn especially if we have a winter without much snow cover.

What about controlling those troublesome perennial weeds like dandelions? Fall is the best time to kill them. As with the grass, perennial weeds are preparing for winter and sending food reserves underground. Applying herbicide around the time of the first fall frost will be most effective.

Following these year-end practices will help to ensure winter survival and improve the lawn’s appearance next year.

 August 9, 2012
Aug 092012

The term “organic farming” was first used in England in the early 1940s, emerging from the biodynamic movement in which a farm was perceived spiritually as a dynamic, living “whole organism.” The concept was brought to the United States in the mid 1940s and widely promoted by J.I. Rodale, founder of Organic Farming and Gardening Magazine (now Organic Gardening) and author of Pay Dirt: Farming and Gardening with Composts and How to Grow Fruits and Vegetables by the Organic Method. Rodale strongly believed in the relationship between living soil and healthy food was achieved by returning animal manures and plant debris to the system by way of composts. The United States Department of Agriculture defines organic as as “an ecological production management system that promotes and enhances biodiversity, biological cycles and soil biological activity. It is based on minimal use of off-farm inputs and on management practices that restore, maintain and enhance ecological harmony.

The growing and selling of produce and products labeled “Certified Organic” is strictly monitored by the United States Department of Agriculture involving a rigorous certification process and complicity with federally mandated regulations for exclusion of non-approved crop management materials, such as synthetic pesticides and fertilizers.

Many home gardeners would like to reduce synthetic chemical use around their children, pets and environment. While they won’t need to certify their backyards, home gardeners may adopt some of the recommended practices to grow flowers, vegetables, fruits and even lawns by using biological and cultural controls, composts, and organic fertilizers along with conventional methods. Some gardeners may choose to completely exclude the use of inorganic fertilizers or growth regulators to reduce dependence on non-renewable resources. Whatever the desire and intent, there are some universally applicable concepts that will help the organic gardener succeed.

closeup of row of seedlings in dirtOrganic vegetable gardening promotes and enhances natural diversity and biological cycles. Rather than relying on synthetic fertilizers and pesticides, organic gardening is based on making the garden self-sufficient and sustainable. You can ease your gardening practices into the organic arena by starting with some of the easier aspects of organic gardening, such as mechanical control of weeds and insect pests.

The first step in this transitioning a garden to organic is improving and maintaining soil fertility and quality. Healthy, fertile soils are basic to successful organic vegetable and fruit production. Management and addition of organic matter, in the form of composts, manures, green manures, and plant residues, is the most important principle to understand for maintaining soil productiveness in an organic system. Organic matter in various forms should be added to the soil annually. There are also many organic fertilizers that can be used to supplement plant nutrition, especially to meet the need for nitrogen and phosphorus. Utah State University has published an excellent organic fertilizer guide, Selecting and Using Organic Fertilizers.

Pest management is the most challenging aspect of organic gardening. Weeds can be controlled with cultivation, pulling, or smothering using mulches. Insects must be closely monitored and controlled using various mechanical methods, predator insects, baits and traps, mild soaps or directed water streams. There are several organically certified insecticides that are useful in the control of insect pests, including Bacillus thuringenisis, insecticidal soaps, rotenone, or natural pyrethrins.

Diseases are best managed through the use of resistant varieties. It is also important to purchase and plant disease-free seed to avoid introducing disease pests into the garden as well as remove and discard diseased plants, rotate annual crops to different places in the garden each year, and keep the garden area free of weeds and dead plant material that may harbor disease organisms. Some leaf-infecting fungi can be controlled using organic fungicides.

A comprehensive list of approved organic materials can be found on the Organic Materials Review Institute web site.

Organic gardening can be simple or complex, depending on the desires of the gardener. There is plenty of good information available on the topic from numerous authoritative sources. Here are some of the best:

View a simple introduction to organic gardening concepts from Mississippi State University

For information on a straightforward, but more detailed approach to organic vegetable gardening, visit this list of University of Florida publications.

For an in-depth discussion of organic soil management principles, read Producing Garden Vegetables with Organic Soil Amendments from the University of Florida.

If you wish to move beyond a cursory understanding of organic gardening practices, select from a series of publications from the University of California, Davis describing detailed organic production principles.

 August 9, 2012
Aug 092012

Fertilizing gardens and landscapes is important to maintain healthy growth and acceptable appearance. Under natural forest conditions, the annual decomposition of leaves, needles and twigs provide a fresh resource of minerals for plants to use. Landscapes usually do not have this nutrient source and are in need of additional minerals since landscape debris is routinely hauled away. There is a plethora of products available to fertilize your plants. It is important to understand basic plant nutrition and fertilizer application principles in order to meet garden fertilizer needs.

Sixteen chemical elements are known to be important to a plant’s growth and survival. Three of these, carbon (C), hydrogen (H) and oxygen (O) are acquired by plants in sufficient quantities from air and water. The other 13 mineral nutrients are acquired by plant roots, which absorb soil minerals dissolved in water. These 13 required mineral nutrients are divided into two groups: macronutrients and micronutrients.

The primary macronutrients are nitrogen (N), phosphorus (P), and potassium (K). Primary macronutrients usually are the ones to be depleted from the soil first because plants use large amounts for growth and survival. Expectations are that some amount of these three nutrients will be needed in the garden every year. The secondary macronutrients are calcium (Ca), magnesium (Mg, and sulfur (S). Fertilization with these nutrients is not always needed. Micronutrients are needed in only very small quantities. The micronutrients are boron (B), copper (Cu), iron (Fe), chloride (Cl), manganese (Mn), molybdenum (Mo) and zinc (Zn). In the high pH soils of southern Idaho, levels of S, Fe, Zn and Mn are often deficient.

Calculating fertilizer application amounts can be a daunting task for the novice gardener. Before fertilizing, you must first determine how much of which nutrient(s) are needed. Determining the amount to apply can be made using historical recommendations found in many garden publications, or using the results of a soil test. The most reliable way is a soil test.  Your local count Extension educator can provide instructions for taking a soil sample.

Next, nutrient content or grade of the fertilizer must be determined. This information is found on the fertilizer package in the form of three numbers. For example, if the fertilizer grade is listed as 10-10-5, the fertilizer contains 10% nitrogen (first number), 10 percent phosphorus (second number), and 5% potassium. If there is a fourth number, it is the percentage of sulfur. The numbers on a fertilizer package are always in the same order, nitrogen-phosphorus-potassium.

The final piece of information that is needed is the land area to be fertilized. Once all of these factors are known, refer to the bulletin Using Soil Tests Results for Garden Fertilization to determine the amount of fertilizer material to apply. For information about fertilizing vegetables, refer to the Soil Preparation for Garden Vegetable section in this web site.

Organic materials are available that can take the place of inorganic fertilizers in the garden. Common forms include blood meal, bone meal, cottonseed meal, sewage sludge, composts, and manures. These fertilizers are usually relatively low in nutrient content compared with conventional formulations and sometimes relatively large quantities need to be applied. Especially when purchased pre-packaged, organic materials can be more expensive than inorganic fertilizers. Colorado State University has published a great discussion on organic fertilizers.

Fertilizing in a landscape is complicated by the fact that different plants have different nutrient requirements. For instance, a lawn uses high amounts of nitrogen while trees generally need very little nitrogen, especially in late summer and fall when applications may induce new growth, which may result in winter cold injury. Managing fertility on other types of plants in Idaho is described in these University of Idaho on-line publications:

By accessing the University of Idaho Resources for Idaho catalog, production and fertilization guides for many additional garden plants can be purchased. Peruse the list at: http://www.cals.uidaho.edu/edComm/catalog.asp?category1=Gardening

Sometimes adding materials to the soil may be beneficial in certain geographical areas while detrimental in other areas. For example, addition of wood ashes and lime make acidic soils more alkaline (higher pH). Consequently, these may be good amendments for northern Idaho’s soils, but not for southern Idaho’s calcareous, alkaline (high in lime) soils.

There are other excellent fertilizer guides on-line. These include:

  • A general discussion about fertilizing a home garden is found in the bulletin, Fertilizing Gardens, published by University of Idaho.
  • A good publication, Fertilizing Your Garden, by Oregon State University that provides information on interpreting soil test results, determining fertilizer needs, and calculating application amounts.
 August 9, 2012
Aug 092012

Composting is a natural biological process that degrades a diverse mixture of ingredients such as leaves, grass, plant material, etc. into a soil-like material called compost. These degraded organic materials (compost) can then be recycled by applying it to the soil. Composting is a good way to eliminate household and yard waste while at the same time improving garden soil. A healthy soil is critical to gardening success. Composting naturally happens, but we can help speed the process by utilizing techniques that enhance the microbe’s (bacteria and fungi) ability to do their job.

Booted foot pushing shovel into dirtComposting can be pursued at many levels, from a gardener who likes to produce “black gold” to the operation of a multi-acre commercial composting facility. Gardeners who compost their own landscaping and food scraps can follow a few simple guidelines and needn’t worry about complex formulas, chemical equations, or studying microorganisms.

The most common way to compost is to collect organic matter in open piles or place the material into bins or barrels. It is important to use only appropriate organic materials in the compost pile, which includes almost any garden or table waste that is plant-derived. Exceptions are plant materials that may harbor disease, may include noxious weed seeds, or material that has been treated with a persistent herbicide. Materials derived from oily foods or animal products should not be included in a compost pile.

A compost pile is created by layering green plant materials, brown and woody plant materials, and garden soil. Once a pile is constructed, composting success depends on providing microbes with the conditions they need to grow and thrive, which are oxygen, moisture and nutrients. These needs are met by turning (mixing) the pile weekly, occasionally adding water to the pile to maintain good moisture, and adding a small amount of fertilizer that is high in nitrogen. Good compost can be created in as little as six weeks with proper temperature and ideal conditions. With less ideal conditions, it may take much longer.

An optional way to compost is to utilize worms. This technique works for composting inside the home for those who live in apartments or otherwise lack space for the more common ways of composting.

For a comprehensive discussion of composting principles, read University of Idaho bulletin, Composting at Home, or the composting section of the University of Idaho Master Gardener’s Handbook.

See the Penn State site for a simplified version of how do home composting.

Learn how to compost using worms from Washington State University.

 August 9, 2012
Aug 062012

Assuming you have normally fertile soils, fruit trees are not usually fertilized at the time of planting or during the first growing season. A soil test is your best resource in determining this and helping you to spot trends in fertility over time. Some Idaho soils, however, are deficient in available phosphorus. You can safely add a cupful of steamed bone meal or 0-45-0 fertilizer to the bottom of a planting hole, mix it with a handful of soil, and plant your tree in the hole. Never add fertilizers containing nitrogen, potassium, or boron to planting holes.

 August 6, 2012
Aug 062012

Ensure that the soil around the tree does not become dry, but avoid overwatering. Your goal should be to keep the soil moist, but not waterlogged. Some gardeners like to build a shallow saucer around newly-planted trees by creating a raised lip of soil about 12 to 24 inches in diameter. This practice can be helpful on soils that drain well until the tree becomes established. On heavier-textured soils, building such saucers can cause problems with the trees. As a general rule, if you build a tree saucer and fill it with water, the water should have drained completely away within an hour or so. If not, remove the saucer. Check newly-planted trees twice weekly to ensure proper irrigation.

 August 6, 2012