August Gardening Tips for Oklahoma


The first week of August was quite pleasant from a meteorological point of view with cooler temperatures and some rain. Unfortunately, the rest of the month can be up to the heat and humidity of the “scorching summer days” that gardeners crave for fall. The following are things that can be done this month in addition to the endless watering, deadhead, and weed control chores.


· August is a good month to start your fall vegetable garden. Kidney beans, cucumbers and summer squash can be replanted for another crop. Beets, broccoli, carrots, potatoes, lettuce, and other cool-season crops can also be planted at this time. For more information, see OSU Information Sheet HLA-6009.

· Soak vegetable seeds overnight before sowing. Once planted, cover them with compost to prevent crusting of the soil and keep it constantly moist. Mulch after germination to keep the planting bed moist and provide shade during initial establishment.


· Towards the end of the month, divide and replant spring-flowering perennials like irises, peonies and daylilies, if necessary. Discard the older portions and replant the keepers in soil improved with compost.


· Water the compost during extremely dry periods to keep it active. Rotate the stack to generate heat for proper sterilization.

· Always follow directions on synthetic and natural pesticide products, if you choose to use them. More is NOT better.

Watch for high populations of caterpillars, aphids, spider mites, thrips, scales and other insects on garden and landscape plants and treat with IPM (Integrated Pest Management) by hand picking, spraying with a hose or spraying with insecticidal soap.

· Water all plants abundantly unless there is sufficient rainfall. It is better to water more deeply, less often and early in the morning. The roots of shrubs and perennials are usually 12 “deep and tree roots are about 18” to 24 “deep so just sprinkling the top of the soil is a waste of time and effort. water and causes damage to plants.

Trees and shrubs

· Stop dead roses by mid-August to help initiate winter resistance. New shoots forced by pruning are susceptible to insect and frost damage.

· Do not fertilize shrubs and trees until next spring. New growth will also be susceptible to insect damage and frost.

· Watch for the second generation of fall moth from late August to early September. Remove the webs that surround the branches and destroy them. If they are too high to reach, you can use a long pole to punch holes and pull them down. Don’t stay under the canvas when pulling it down! I let the birds take care of the borers when they fall to the ground.

Lawn and turf

Winter herbaceous grasses like Poa annua, better known as annual bluegrass, smooth brome, henbit (the one that makes your lawn a pretty purple carpet), chickweed, chickweed, cranesbill and shepherd’s purse are The most common winter annuals are the weeds that plague Oklahoma gardeners during the colder months. These winter weeds are not only unsightly, but heavy infestations can damage Bermuda grass during spring greening.

A good rule of thumb for pre-emergence to keep winter weeds from sprouting is that they should be applied from the third week of August through September 15 in Oklahoma. After September 15, weed seeds are already starting to germinate and will appear as large ugly green spots in your dormant lawn in the winter. We in southern Oklahoma can push the pre-emergence application date back to October, generally. I know we were still mowing until October for the past two years, and it was hot until Thanksgiving; therefore, soil temperatures were still high enough that winter weeds did not start to germinate. Check out Oklahoma Mesonet for in-depth coverage of all things Oklahoma weather, including ground temperatures at various depths.

For more information on lawn care in Oklahoma, see the following OSU fact sheets:

HLA-6420 Lawn Management in Oklahoma

HLA-6421 Weed Control in Domestic Lawns

L-253 Don’t Bag It Lawn Care Plan

If you want to learn more about lawn care and fall gardening in South Oklahoma and more, Betty Sue Tow and I will teach you Gardening and landscaping for the fall semester on Mondays 6-8 at Southern Tech in Ardmore. You can drop by to register or call 580 223-2070.

Learn what, when, where, and how to plant in South Oklahoma, and how to work with what you have to create a beautiful yard that is both beautiful and good for the environment. Classes will include Organic Gardening, Landscaping, Xeriscape Gardening, Native Plants, Vegetable Gardening, Oklahoma Proven Plants, Lasagna Gardening, Raised Beds, Crepe Myrtles, Integrated Pest Management , Plants to Pass, Cottage Gardening (New American Gardening), Soil Preparation, Seed Start, Plant Propagation, and much more. Hope to see you in class and good gardening!


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