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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 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

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 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