Horticulture 2023 Newsletter No. 44

Horticulture News



Blog Post: http://ksuhortnewsletter.org

Video of the Week: Cleaning Up Your Garden for the Fall



Kansas Turf & Landscape Conference

The 73rd Annual Kansas Turf & Landscape Conference will be held on Wednesday, November 29 and Thursday, November 30 at the Hilton Garden Inn, Manhattan. The conference is an excellent way to learn about turf and landscape management, visit with old friends, network with new ones, and see all the latest products and supplies from local and national vendors.

The conference has been approved for commercial pesticide recertification hours:

1 Core hour

3A – 7 hours

3B – 7hours

GCSAA education points and International Society of Arboriculture CEUS will also be available by attending the conference.


For more information, go to https://www.kansasturfgrassfoundation.com/



Work fallen tree leaves into the garden every two weeks to increase organic matter.
Drain hoses and irrigation systems before winter.
Fertilize cool-season lawns if you haven’t done so yet.
Dig up and store tender bulbs such as cannas, callas and gladiolas after the leaves are browned by frost.

Horseradish has the most growth from the end of summer into early fall so harvesting should be delayed until just before the ground freezes, usually November to December. Though horseradish is a perennial, it is most commonly grown as an annual and harvested each year when the leaves have died back from frost.

Dig a trench alongside the row of plants exposing the roots. Use a shovel or pull the plants by hand toward the trench releasing them from the soil.

Remove the foliage to about one inch above the crown. Remove smaller, side roots and collect the larger roots for storage. Smaller roots can be cut into six- to eight-inch-long sections and planted now for next year’s crop. Alternatively, you may choose to leave horseradish roots in the ground until spring. Apply a thick layer of mulch to prevent the ground from freezing and harvest as needed. Horseradish can easily spread throughout the garden if not contained so harvesting each year is important.

Wash the roots thoroughly and dry before storing in plastic bags in the refrigerator. When preparing horseradish, peel the roots and cut into sections. Blend the root pieces along with a little water and a couple of ice cubes. When blended, horseradish releases oils with strong fumes that can be an irritant. This is what gives horseradish the strong flavor but use caution when opening the blender to avoid getting it into your eyes. Incorporating vinegar stops this reaction. If vinegar is added immediately after blending the horseradish will be mild. Wait a few minutes to add the vinegar if you want a stronger flavor. Two to three tablespoons vinegar per cup of horseradish is sufficient. One-half teaspoon of salt can also be added for flavor. (Cynthia Domenghini)


Soil Prep Now for Peas Next Spring

Peas need to be planted early in the spring to reach maturity before the warm weather arrives. Preparing the soil in the fall will allow you to get the seeds planted without trying to work wet or frozen soil next spring.

Peas do best with loose, well-drained soil. Incorporate organic matter into the soil now so it has time to decompose before planting. Determine fertilization needs through a soil test. Remember that peas are legumes and fix nitrogen. Avoid adding too much additional nitrogen to the soil or pod production may decrease.

In the spring, when the soil temperature reaches 40 degrees peas can be planted. As the seeds germinate watch for rabbits and other wildlife that are seeking a food source. Fencing can be added to protect your crop. (Cynthia Domenghini)



Knotweed Control

Knotweed (Polygonum aviculare) is an annual warm season weed. Its prostrate growth can be seen in lawns that are thin and areas with compacted soil that prevent desirable plants from thriving.

Controlling for knotweed is best done with prevention by maintaining a thick, healthy lawn. This includes following proper methods for aerating, fertilizing, watering and mowing. Limiting the environmental stress to a lawn will keep the lawn strong and reduce the presence of weeds. Lawns used for recreation often suffer stress from overuse. Pay attention to areas of the lawn that have high use and look for solutions to prevent wear and tear.

There are times when chemical methods are the most effective route for weed control. Preemergence herbicides are applied to the soil before the weeds have germinated and block the seeds from growing. Knotweed can sometimes germinate beneath a snow cover so the preemergence should be applied during November/December. Pendimethalin (Scotts Halts), Surflan (Weed Impede), Barricade, Dimension and XL are labeled for knotweed. (Note: Pendimethalin, Barricade and Dimension can be used on all Kansas turfgrasses, while Surflan and XL can only be used on tall fescue and warm-season grasses such as buffalograss, zoysiagrass and bermuda).

Postemergence herbicides are applied to growing weeds. A combination postemergence product such as Trimec, Weed-Out, Weed-B-Gon or Weed Free Zone can be effective after the knotweed has emerged in the spring but is still young.

Something to keep in mind is if you plan to seed the lawn in the spring you should not use a preemergence herbicide as this will block the growth of the grass seeds as well as the weeds. If you plan to seed in the spring, you may choose to till the area prior to planting which can help control against knotweed. To avoid tilling you may choose to wait for knotweed to appear in early spring, apply the postemergence and wait at least one month before seeding the lawn. (Cynthia Domenghini)



Water Landscape Plants Before Winter if Needed

Trees and shrubs need moist soil even during the colder months. Though plants may appear fine above ground throughout the winter, damage caused by winter drought can be evident in late spring and summer when the weather warms and the weakened root system cannot support the growth. Affected plants are more susceptible to damage from disease and insects.
Providing water deep into the soil (at least 12-inches) gives a majority of the roots access. This is especially important for young trees and shrubs that haven’t developed an extensive root system yet. Even trees and shrubs planted two to three years ago can suffer damage from drought. Evergreens are susceptible to drought because they continue losing water through their leaves during winter.

To check for soil moisture, push a metal rod into the soil. Dry soil is much harder to push through than wet so if you aren’t able to easily insert the rod at least 12 inches into the soil, it’s time to water. Water on a day when the air temperature is over 40 degrees F and the soil isn’t frozen. Watering mid-day allows time for the water to soak in before the temperature drops in the evening. Water should be allowed to soak in slowly in several areas beneath the dripline. The dripline is the area beneath the outermost branches of the plant.

Soaker hoses can be used to apply water slowly however they are not always uniform in distribution. To remedy this, hook both ends of the soaker hose to a Y-adapter to equalize the pressure. The specific parts you need are shown in the photo above and include the soaker hose, Y-adapter and female to female connector. It is also helpful if the Y-adapter has shut off valves so the flow can be controlled. Too high a flow rate can allow water to run off rather than soak in.

To determine how long the soaker hose should run, check the soil regularly and calculate the time it took for water to reach 12-inches deep into the soil. In the future you can water based on this timing. If you notice run-off you may need to slow down the water or build a berm to keep the water over the rootzone.

If we have a “normal” winter, watering once before spring should be adequate. However, if the winter is warm and dry, watering once a month may be needed. A layer of mulch (up to three-inches) over the soil helps retain moisture and regulate temperature reducing the need for supplemental water. This also protects the soil from repeatedly freezing and thawing which leads to cracking. Soil cracks put roots at further risk of drying out. Mulch applied beneath the dripline of trees should be kept two- to four-inches away from the trunk to prevent damage to the tree. (Cynthia Domenghini)


Maintaining the Compost Pile

Composting can be done year-round which is good considering the amount of plant waste available this time of year. Remember to keep the heap balanced with the amount of “greens” and “browns”. This can be done by alternating layers of fallen leaves (browns) with fresh plant material (greens) such as grass clippings. If your pile is beginning to smell bad you may have too much green waste. Add in straw, sawdust, woodchips or even shredded newspaper to balance it.

Decomposition will slow during cold weather. Since the inside of the pile is more insulated than the outer edges, decomposers are able to continue working even when the outside of the pile may be frozen. Wait to turn the pile until warmer spring weather arrives to keep the interior of the pile warm.

It is also important to keep the compost pile moist. If the pile is too dry the bacteria and fungi are not able to break down the raw materials efficiently. A sprinkler can be placed on top of the pile to add moisture if there has not been any precipitation. Shredding materials prior to adding them to the heap will also expedite decomposition.

For more information on composting check out our video at http://tinyurl.com/jn6yppo. (Cynthia Domenghini)


Garden Hoes

There are a number of different designs for garden hoes. My favorite three are the traditional, circular and scuffle. The traditional hoe is used to chop weeds or to lightly scrape the soil surface to kill weeds that are just emerging. Even though it is the most popular garden hoe, it is the one I use the least.

The scuffle hoe is the most used hoe I own. It covers a lot of ground quickly and kills weeds without disturbing the soil as much, so it is less likely to bring up weed seed. This type of hoe can be more difficult to find than the traditional hoe and a mail-order company may be needed. However, check with your local garden center as they are more likely to carry them than other suppliers. There is a company, Prohoe Manufacturing, LLC, in Munden, Kansas that makes these hoes in several different widths as well as a number of other hoe types. All are made out of recycled disc blades. (https://www.prohoe.com/ )

The circular hoe is more specialized. It features a circular “blade” in which only the bottom is sharpened. This allows you to hoe very close to existing plants without harming them as the sides of the circle are dull. This one was invented by an Oregon Extension Master Gardener in the late nineties. Though short-handled ones are relatively easy to find, the long-handled types are more difficult. As a matter of fact, the only source I could find was from Red Pig Tools. See https://www.redpigtools.com/Circular-Hoe-Long-Handle_p_1405.html .

Though these three types are my favorite, don’t be afraid to try others to see how they work for you. (Ward Upham)


Begin Rabbit Protection Now

Wildlife are busy scavenging for food; newly planted trees and shrubs make a great option during the winter. Rabbits can be deterred with a barrier at least two-feet tall of one-inch wire fencing such as chicken wire. Create a cylindrical fence surrounding the tree/shrub. This can be removed or left in place during the spring as long as the diameter is wide enough to not restrict plant growth. Plastic tree wraps are another option. Liquid repellents can be used but aren’t effective unless reapplied after every rain. (Cynthia Domenghini)



Cynthia Domenghini, Instructor & Horticulture Extension Specialist

Ward Upham, Extension Associate



Department of Horticulture and Natural Resources

1712 Claflin, 2021 Throckmorton

Manhattan, KS 66506

(785) 532-6173

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