GARDEN TO-DO
Avoid fertilizing ornamentals now so they harden off before winter
Take cuttings from cold-sensitive annuals to root for wintering indoors. See: https://kansashealthyyards.org/all-videos/video/cuttings-to-grow-inside-for-winter
Turn compost pile and add water when dry
Light pruning of shrubs and trees where 10% or less of the plant is removed can be done any time of year. Heavier pruning should be done in the spring.
Fertilize strawberry bed for added flower bud development and larger crop next year.
Too late to spray for bagworms but can pull them off and dispose of them if practical.
VEGETABLES
Cover Crops for the Off-Season
Cover crops are grown for many benefits including to improve soil quality, reduce weeds and erosion and sometimes to promote the garden ecosystem by providing food sources for pollinators. They are typically not grown for their harvest as the primary benefit.
The best cover crop for your garden depends on the purpose, planting time and planned method of terminating the crop.
Small grains such as wheat should be seeded from mid-September to late October at a rate of 3/4 to 1 pound of seed per 1,000 square feet. Spring oats can also be seeded until mid-September but the rate should be 2 to 4 pounds per 1,000 square feet. Spring oats will die back in the winter and can be tilled under in the spring. Daikon radishes are another good cover crop because the large taproot penetrates the hardpan. After the radishes die back in the winter, the loosened soil is better able to retain water.
Hairy vetch, alfalfa and sweet clover are legumes which means they fix nitrogen. Seed these cover crops at a rate of ¼ to ½ pound of seed per 1,000 square feet of garden. Hairy vetch and alfalfa can be seeded from mid-August to late September while sweet clover should be seeded only until early-September. Visit the Kansas Garden Guide for more cover crop recommendations for home gardeners.
FLOWERS
Spring-Flowering Shrubs
Spring-flowering shrubs typically establish buds for next year in August and September. Avoid pruning these shrubs now as it will negatively affect next year’s bloom. Water, as needed, this time of year to support the plants’ new growth.
Examples of spring-flowering shrubs include Forsythia, Flowering Quince, Almond, Beautybush, Deutzia, Pyracantha, Lilac, Mock Orange, Cotoneaster, Weigela, Viburnum and Witch hazel.
Dividing Peonies
If your peonies didn’t bloom as expected this year it’s possible they need to be divided. Peonies don’t require dividing often, but doing so periodically can promote healthier plants. You also get the benefit of increasing your plant collection.
Cut stems just above the soil surface. Dig up the entire root system and remove the soil from the roots. Divide the root clump into small sections using a sharp knife. Each section should have three to five buds and healthy roots. Sections with fewer buds will take longer to bloom.
Choose a planting location that receives sunlight for at least half of the day. Dig a hole large enough that the roots and buds will be covered by one to two-inches of soil. Plants buried too deep may not flower. Backfill and water thoroughly. Space dwarf peonies at least two-feet apart and standard peonies four-feet apart.
It may take a couple of years for the divided plants to return to full bloom productivity. Kansas’ winters have periods of freezing and thawing which can uproot plants. Protect newly divided peonies, by covering them with a layer of straw, leaves or compost after the soil freezes.
PESTS
Fall Armyworms
Though often found in agricultural crops, fall armyworms can be present in certain turfgrass species and we’ve had a few reports of them recently.
Description: Young larvae are ½ to ¾ inches long. Mature larvae can reach 1½ inches long. Fall armyworms can be identified by the inverted “Y” on top of the dark head. Adult moths are ½ inch long. The two front wings are brown-grey. Males have more dark markings than females.
Life Cycle: As a tropical insect, fall armyworms are not able to overwinter in Kansas limiting them to 2-4 generations each year. Moths migrate to their seasonal home and lay hundreds of eggs in clusters. Larvae hatch and begin feeding. Once established, new generations can occur every 23-25 days.
Damage: Larvae feed on grass blades. Heavy infestations will occasionally chew the blades to the crown. Though the damage may be unsightly it does not typically kill the grass. Regrowth of the turfgrass can be expedited with rain and/or irrigation.
To read more about fall armyworm and control options access our publication from the Horticulture Resource Center: Fall Armyworm.
Learn more from K-State Entomology: Fall Armyworm.
TURF
Reading Grass Seed Labels
Before planting grass seed pay close attention to the percentages on the label. Depending on the seed quality, you could be planting weeds along with the desired grass.
Check the percentage of weed seed listed. This will tell you how much weed you will be introducing if you plant this seed mix. For example, if this number is 0.5% weed seed, approximately 12 to 16 weeds will be planted per square foot. If it is less than 0.01% weed seed that is good but 0% is best.
Check “Other Crop” on the label as well and choose a grass seed with a low percentage. “Other Crop” includes any species grown intentionally such as turfgrasses and pasture grasses. Some species of grassy weeds fit into this category and legally do not have to be named when they’re included in a mix if they constitute less than 5% of the contents.
“Other Crop” can also include more desirable species that will not significantly impact your lawn. Without knowing what is included it’s best to choose a seed where this number is as close to zero as possible. Quality seed typically has 0.01% “Other Crop” or less.
Fall Lawn Tips
September is the best time to seed cool-season grasses.
Seeding New Lawns
Use good quality, certified seed; avoid seed with significant levels of “weed” and “other crop.” (See last week’s newsletter – #33 – for an explanation of these terms.)
Use recommended seeding rates and distribute well. Seeding at a rate higher than recommended can cause issues with disease and environmental stress.
Good seed to soil contact is critical! Aeration prior to seeding is one way to promote this. Topdressing and raking to cover seed are some other methods of enhancing seed to soil contact. Thatch build-up will hinder seed to soil contact. See core-aerating below is thatch is a problem in your lawn.
Light, frequent irrigation is necessary the first few weeks after planting and may be required several times daily depending upon weather. Soil should remain moist but not waterlogged.
Minimize traffic on the area until seedlings are ready to be mowed. Begin mowing once seedlings reach 3-4 inches tall.
Overseeding an Existing Lawn
Prior to planting, mow the area low (1 to 1-1/2 inches) to reduce competition with seedlings and help improve seed contact with soil.
Apply fertilizer based on soil test results or use starter fertilizer at rate recommended on the bag.
Water light, but often keeping soil moist but not waterlogged.
Fertilize cool-season grasses.
Use a quick-release source of nitrogen.
Apply 1 to 1-1/2 pounds of actual nitrogen per 1,000 square feet.
Core-aerating
Removes cores of soil to relieve compaction, speed up thatch decomposition and improve water, nutrient and oxygen movement in soil.
Soil should be moist but not saturated.
Holes should be 2-3 inches apart and 2.5 to 3 inches deep.
Cores can be left on the surface and will break down naturally
MISCELLANEOUS
Composting: What to Add
The most efficient compost has the right combination of carbon (browns) and nitrogen (greens) ingredients. Examples of browns include dried items such as leaves, twigs, straw, wood chips and sawdust. It is best to chop up the dried materials to expedite decomposition.
Examples of greens are coffee grounds, egg shells, fruit/vegetable scraps and fresh plant parts. Manure from farm-type animals (cows, sheep, etc.) is another green waste that can be added. Pet waste should not be used in compost.
Layer the compost pile alternating between six to eight inches of brown waste and two to three inches of green waste until the pile reaches three to five feet tall. You can wet down each layer of “browns” as you build the pile. This combination of materials creates an ideal environment for microorganisms that promote decomposing.
Should I Compost My Tomato Plants?
There are some common problems that occur with tomatoes which can easily spread to next year’s garden if the compost heap does not reach adequate temperatures for a long enough period of time to kill the spores. A compost pile that is not properly balanced with the amount of greens and browns and/or one that is not maintained to promote air circulation will not decompose as quickly. If compost is used before it is fully decomposed, diseases can easily spread to the plants it is supposed to be supporting.
If you suspect, or know, your current plants are harboring a disease, it is safest to destroy them when they have finished producing, rather than composting them.
QUESTION of the WEEK
What’s happening to the bark on my tree?
We are finding bark pieces on the ground beneath a mature tree in our yard. There are sections on the branches where the bark is stripped away. Any ideas what is causing this?
This looks like damage caused by squirrels. This kind of damage can sometimes cause girdling resulting in branch die-back. For recommendations, contact your local extension agent or read our KSRE Publication: Squirrel Damage to Trees
Contributors:
Cynthia Domenghini, Horticulture Instructor
K-State Turfgrass Blog
K-State Extension Entomology
K-State Wildlife and Outdoor Enterprise Management
Division of Horticulture
1712 Claflin, 2021 Throckmorton
Manhattan, KS 66506
(785) 532-6173
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Cynthia Domenghini, Ph.D.
Instructor, Horticulture and Natural Resources
Kansas State University
[email protected]
