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Aug 172012
blue fescue

Fescues add texture to naturalized plantings. Photo courtesy of Judy Sedbrook

Water Conserving Landscapes

These grasses require little care and minimal water after establishment to remain attractive. They are generally drought and heat tolerant.

Common Name Scientific Name Regional Adaptation
Arizona Fescue Festuca arizonica N, SW, SC, SE
Big Bluestem Andropogon gerardii N, SW, SC, SE, HA
Blue Fescue Festuca glauca N, SW, SC, SE, HA
Blue Grama Bouteloua gracilis N, SW, SC, SE, HA
Blue Oat Grass Helictotrichon sempervirens N, SW, SC, SE, HA
Idaho Fescue Festuca idahoensis N, SW, SC, SE, HA
Indian Grass Sorghastrum nutans N, SW, SC, SE
Indian Rice Grass Oryzopsis hymenoides N, SW, SC, SE, HA
Little Bluestem Schizachyrium scoparium N, SW, SC, SE, HA
Prairie Dropseed Sporobolus heterolepsis N, SW, SC, SE, HA
Prairie June Grass Koeleria pyramidata N, SW, SC, SE, HA
Sand Love Grass Eragrostis trichodes N, SW, SC, SE
Side Oats Grama Bouteloua curtipendula N, SW, SC, SE, HA

Maiden grass

Maiden grass holds up well in winter. Photo courtesy of Judy Sedbrook

Naturalized Plantings

Many grasses will thrive under no-care situations in Idaho, even in the driest areas. They can be planted with native wildflowers and shrubs to create attractive, natural-looking landscapes. Some of the best grasses for naturalizing are spreading, rather than clumping in growth habit, giving them the ability to fill in bare areas.

Common Name Scientific Name Regional Adaptation
Arizona Fescue Festuca arizonica N, SW, SC, SE
Big Bluegrass Poa secunda var. canbyi N, SW, SC, SE, HA
Blue Fescue Festuca glauca N, SW, SC, SE, HA
Blue Grama Bouteloua gracilis N, SW, SC, SE, HA
Buffalo Grass Buchloe dactyloides N, SW, SC, SE
Crested Wheatgrass Agropyron cristatum N, SW, SC, SE, HA
Idaho Fescue Festuca idahoensis N, SW, SC, SE, HA
Prairie Dropseed Sporobolus heterolepsis N, SW, SC, SE, HA
Prairie June Grass Koeleria pyramidata N, SW, SC, SE, HA
Sandberg Bluegrass Poa secunda var. sandbergii N, SW, SC, SE, HA
Sheep Fescue Festuca ovina N, SW, SC, SE, HA
Snake River Wheatgrass Elymus wawawaiensis N, SW, SC, SE, HA

Winter grass

Tall grasses provide winter texture

Grasses for Winter Interest

Although consistently wet or moist soils are not common, especially in southern Idaho, such sites are often created artificially in the landscape. Below is a list of plants that thrive under such conditions.

Common Name Scientific Name Regional Adaptation
Blue Oat Grass Helictotrichon sempervirens N, SW, SC, SE, HA
Feather Reed Grass Calamagrostis x acutifolia N, SW, SC, SE, HA
Flame Grass Miscanthus ‘purpurescens’ N, SW, SC, SE, HA
Korean Feather Reed Grass Calamagrostis brachytricha N, SW, SC, SE
Maiden Grass Miscanthus sinensis N, SW, SC, SE
Northern Sea Oats Chasmanthium latifolium N, SW, SC
Switch Grass Panicum virgatum N, SW, SC, SE, HA

Penn Rub grass in container

Tender fountain grass makes a good container specimen. Photo courtesy of Judy Sedbrook

Tender Grasses Grown as Annuals

Some of the most attractive ornamental grasses are not hardy in Idaho. This includes many of the Pennisetum varieties that come in a remarkable array of foliage and flower spike colors. Many of these will still grow here if treated as annuals. Some of the tender grasses make very good container specimens. Here is a short list of tender grasses that can be grown as annuals.

Common Name Scientific Name Regional Adaptation
Feather Top Pennisetum villosum N, SW, SC, SE, HA
Lemon Grass Cymbopogon selloana N, SW, SC, SE, HA
Purple Millet Pennisetum glaucum N, SW, SC, SE, HA
Ruby Grass Melinus nerviglumis N, SW, SC, SE, HA
Tender Fountain Grass Pennisetum setaceum N, SW, SC, SE, HA
 August 17, 2012
Aug 162012

During the spring in April to mid May when temperatures are still cool, most cool-season lawns in Idaho will use about one inch of water each week. From about late May to mid August, lawns will use about 2 inches of water per week or slightly more. Then, from mid August to late September they use just over one inch of water. During periods when significant amounts of precipitation is received, lawn sprinklers systems should be turned off. There is no need to irrigate when the soil is already filled to capacity.

Depending on the year and the onset of winter, grasses will still use close to an inch per week in October, and it is important to keep the soil moist, not overly wet, but moist going into winter. This will help prevent winter desiccation damage.

Lawns with significant shade and wind protection will not need as much water, but remember that the grass will be competing with tree roots for water and nutrients, so extra attention needs to be given to these landscapes.

 August 16, 2012
Aug 132012

Selecting the proper time to prune is important. Heavy pruning at the wrong time of year can stimulate unwanted growth or prevent flowering or fruiting. Before pruning, consider time of year, type of plant and flowering periods of certain plants. See the table below.

Time of Year to Prune Various Types of Plants.
Type of plant Fall Winter Spring Summer Comments
Early Late Early Late Early Late Early Late
Deciduous shrubs for shrubs
that flower before
June 1
Deciduous shrubs for shrubs
that flower after
May 30
Conifers –
Shrubs and
All conifers
except for pines
(see below)
For shrubs grown
for flowers
Broad leaf
For shrubs grown for foliage (hedge)

When to Prune New Growth on Pines

Pines have buds only at the tip of the branches. If a branch is pruned after a growth flush and the terminal bud is removed, regrowth is impossible. Pine branches should be pruned or pinched in early summer when the new branch (candle) has begun to elongate but before the needle bundles open. This pruning causes the growth to be more compact but still allows buds to form for the following year.

 August 13, 2012
Aug 102012

Pest and Disease Management
Fruit Thinning

Healthy and productive fruit trees require regular care throughout the year. A few of the more important tasks are listed here. Click here for links to more complete guidance on fruit tree care.

In early spring before the new leaves appear, examine the trees carefully for signs of damage from winter cold, snow and ice, diseases, girdling or other damage from animals, and signs of pests or pest damage.

Prune your fruit trees. Normally, we prune fruit trees in late winter or early spring before the buds begin swelling. First remove any diseased or damaged wood. Damaged and diseased wood can be pruned out any time of the year. If the branch is or may be diseased, rinse your pruning shears after every cut in a solution of 20% household bleach in water or 70% ethyl or isopropyl alcohol. Do not compost diseased or pest infected branches.

Remove all sprouts arising from the roots and trunk below the graft union. Next, concentrate on building a strong structure that will support the branches and crop. Remove enough wood to maintain an open canopy that allows light to penetrate to the trunk and air to circulate freely through the tree. Most water sprouts come off at this time. Water sprouts are vigorous, vertical shoots that can easily develop into multiple leaders and create a crowded, hard to manage tree. With some crops, pruning can help manage the tree height by removing branches above a desired height. Height management through pruning works well for peaches, nectarines, and apricots. For apples and pears on dwarfing rootstocks, pruning is also valuable for controlling height. Controlling cherry and plum tree height with pruning can be difficult.

 August 10, 2012
Aug 092012

Inspecting a treeAbout this time of year, I begin to experience what I call “garden itch”. I really want to get out and dig in the dirt and make something grow. Garden books tell us winter is the time to study garden catalogues, complete seed orders, and make plans for the next spring. While fun, these activities don’t seem to satisfy my itch.

However, all is not lost. There is one important gardening activity that is best completed in the winter. It involves conducting a thorough tree inspection. This is especially effective for deciduous trees because they no longer have leaves to hide their problems. So, on a sunny winter day, put on your hat and boots and take a close look at your trees.

What to look for:

Although winter may not be the time you want to solve tree problems, it is the time to identify them. Here is a list of things you may want to look for.

Inspecting a treeStructural Problems: look for situations that can be early signs of weakness that may later lead to branch or tree failure. Many of these can be solved later on through judicious pruning. Specifically, look for branches with a poor attachment angle. Where they join the trunk, branches should be directed slightly upward at an angle of 45 to 60 degrees. If they are too horizontal, or too upright, they will become weak. Plan to remove such problem branches, if it can be done without destroying the structure of the tree.

Inspecting a treeAlso, look for cracks and splitting around branch junctions. If you find such damage on large trees, you may need to access some professional help to determine the best action. On small trees, you can reshape the tree to relieve the pressure that is causing the problem and help the tree heal itself. The last thing to look for is something called included bark. This is a situation where the tree does not make normal wood on the top of the branch junction and instead produces bark in the joint. It can be recognized by the soft, corky tissue (it may create an open crevice or be closed) that is present on top and down into the branch union. This makes the branch very weak. It is often associated with a steep branch angle. Plan to remove these weak branches if feasible.

Inspecting a treeArchitecture and Appearance: When the tree is bare, you can step back and look at its overall growth habit. Determine whether or not it has good balance and overall appearance. Decide if the crown needs to be raised, lowered, or cleaned (but never topped). Record a pruning plan that can be implemented in the spring to improve the tree’s appearance and functionality.

Pests and Disease Problems: Although pests are typically not damaging during the winter, it is still a good time to look for problems that can be addressed during spring or summer. Some of the most destructive insect pests on trees are borers. Look for the small holes, the sawdust-like frass, or loosened bark that may indicate a problem is looming. Other types of insects such as aphids or beetles will overwinter as eggs on the trees and may become problematic next summer. Do some homework before the inspection and find out what to look for based on common problems for the tree species you are inspecting. Also, check for disease problems that appear as cankers on the bark. If you find such problems, study up on the solutions and prepare to deal with them when the season is right. That will give you one more scratch for the gardening itch.

A good winter tree inspection will identify problems you may not know you have. It will also give you time to come up with a good solution to one or more of the many issues that affect tree health. Winter may be a slow time for garden chores, but it does not need to be unproductive.

—Stephen Love, Consumer Horticulture Specialist

 August 9, 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