Horticulture 2020 Newsletter No. 40
October 6, 2020
https://hnr.k-state.edu/extension/info-center/newsletters/index.html
Blog Post: http://www.ksuhortnewsletter.org
Video of the Week: How to Test Your Soil for Nutrients
https://kansashealthyyards.org/all-videos/video/how-to-test-your-soil-for-nutrients
Events
Kansas Forest Service Tree, shrub Seedling Sale, September 1 – October 15
Reminders
- Add organic matter to vegetable garden this fall.
- Bring houseplants in if you haven’t already.
- Dig sweet potatoes
ORNAMENTALS
Pruning Trees and Shrubs in the Fall
Pruning in August can stimulate new growth that is less hardy during the winter. But what about pruning at this time of year? Woody plants move sugars and other materials from the leaves to storage places in the woody portions of the plant just prior to leaf fall and we would like to maximize those stored energy reserves. Even pruning later in the fall can cause a problem by reducing the cold hardiness of woody plants. Dr. Rich Marini at Penn State Extension has written , “Based on everything that has been published we can conclude that woody plants do not attain maximum cold hardiness when they are pruned in the fall. Trees are affected more by heavy pruning than light pruning.” However, this does not mean that woody plants pruned in the fall will necessarily suffer winter damage. In most cases, I think we can get away with the old adage of “prune whenever your pruners are sharp.” However, damage can occur if we have a sharp drop in temperature before plants are completely hardened off. Also, marginally hardy plants are more susceptible to winter damage, especially if pruned in the fall. Though light pruning and removal of dead wood are fine this time of year, you may want to delay severe pruning until spring.
Consider pruning to be “light” if 10% of less of the plant is removed. Dead wood does not count in this calculation. Keep in mind that even light pruning of spring-blooming shrubs such as lilac and forsythia will reduce flowers for next year. We normally recommend that spring-bloomers be pruned after flowering.
Shrubs differ in how severely they can be cutback. Junipers do not break bud from within the plant and therefore should be trimmed lightly if you wish to keep the full shape. Overgrown junipers should be removed. On the other hand, there are certain shrubs that can be pruned back severely during the spring. Rejuvenation is the most severe type of pruning and may be used on multi-stem shrubs that have become too large with too many old branches to justify saving the younger canes. All stems are cut back to 3- to 5-inch stubs. This works well for spirea, forsythia, pyracantha, ninebark, Russian almond, sweet mock orange, shrub roses, and flowering quince. Just remember that spring is the correct time to do this, not now. (Ward Upham)
Is It a Maple or an Oak?
Sometimes people are unsure on how to tell the difference between a maple and an oak. The easiest way is to look at how the leaves are arranged on the stem. Maples are opposite leaved and oaks are alternate. Opposite leaved plants such as maples and ash have leaves directly across from one another. Alternate leaved plants have leaves alternating up the stem; one on one side and the next, further up the stem, on the other. (Ward Upham)
FLOWERS
Clean up Iris Beds this Fall
Iris are known for a couple of common problems: a fungus disease known as iris leaf spot and an insect named iris borer. Though both cause problems in the spring, now is the time to start control measures. Both the fungus and eggs of the borer overwinter on old, dead leaves. Remove dead leaves and cut back healthy leaves by ½ this fall to reduce populations of these pests. Also remove other garden debris from the iris bed. This can significantly cut down on problems next spring. (Ward Upham)
MISCELLANEOUS
Fall is a Good Time for Soil Testing
Though we often think of soil testing as a spring chore, fall can actually be a better time. Soil-testing laboratories are often very busy during the spring resulting in a longer turnaround from submission to recommendations. Also, soils in the spring are often waterlogged, making taking samples difficult. If your soil test suggests more organic matter, fall is a much better season because materials are more available than in the spring (tree leaves), and fresher materials can be used without harming young tender spring-planted plants.
Begin by taking a representative sample from at least six locations in the garden or lawn. Each sample should contain soil from the surface to about 6 to 8 inches deep. This is most easily done with a soil sampler. Many K-State Research and Extension offices have such samplers available for checkout. If you don’t have a sampler, use a shovel to dig straight down into the soil. Then shave a small layer off the back of the hole for your sample. Mix the samples together in a clean plastic container and select about 1 to 1.5 cups of soil. This can be placed in a plastic container such as a resealable plastic bag.
Take the soil to your county extension office to have tests done for a small charge at the K-State soil-testing laboratory. A soil test determines fertility problems, not other conditions that may exist such as poor drainage, poor soil structure, soil borne diseases or insects, chemical contaminants or damage, or shade with root competition from other plants. All of these conditions may reduce plant performance but cannot be evaluated by a soil test. (Ward Upham)
Harvesting and Curing Black Walnut
Black walnuts are ready to be harvested when the hull can be dented with your thumb. You can also wait until the nuts start falling from the tree. Either way it is important to hull walnuts soon after harvest. If not removed, the hull will leach a stain through the nut and into the meat. The stain will not only discolor the meats but also give them an off flavor.
There are several ways to hull walnuts including running them through a corn sheller or pounding each nut through a hole in a board. The hole must be big enough for the nut but smaller than the hull. An easier way is to run over the nuts with a lawn tractor. This will break the hull but not crack the nut.
Note that walnut hulls contain a dye that will stain concrete, your hands or about anything else it touches. Wear gloves as the stain is almost impossible to remove.
Wash hulled nuts by spreading them out on the lawn or on a wire mesh and spraying them with water or placing them in a tub of water. If you place them in a tub, the good nuts should sink. Those that float are probably not well-filled with kernels. Next, dry the nuts by spreading them in layers no more than three deep in a cool, shady and dry place such as a garage or tool shed. Drying normally takes two weeks. (Ward Upham)
Contributors: Ward Upham, Extension Associate
Department of Horticulture and Natural Resources
1712 Claflin, 2021 Throckmorton
Manhattan, KS 66506
(785) 532-6173
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Ward Upham
Extension Associate
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