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Oklahoma City, OK 73102

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Monthly Horticulture Tips

August Gardening Tips

Oklahoma Cooperative Extension Service, Division of Agricultural Sciences and Natural Resources

Department of Horticulture & Landscape Architecture, Oklahoma State University

David Hillock, Consumer Horticulturist


  • Towards the end of the month, divide and replant spring-blooming perennials like iris, peonies, and daylilies if needed.

Fruits & Nuts

  • Continue protective insect applications on the fruit orchard. A good spray schedule is often abandoned too early. Follow directions on last application prior to harvest. (EPP-7319)

Tree & Shrub

  • Discontinue deadheading roses by mid-August to help initiate winter hardiness.
  • Watch for second generation of fall webworm in late August/early September. Remove webs that enclose branches and destroy or spray with good penetration with an appropriate insecticide.


  • August is a good month to start your fall vegetable garden. Bush 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. (HLA-6009).
  • Soak vegetable seed overnight prior to planting. Once planted, cover them with compost to avoid soil crusting. Mulch to keep planting bed moist and provide shade during initial establishment. Monitor and control insect pests that prevent a good start of plants in your fall garden.
General Landscape
  • Water compost during extremely dry periods so that it remains active. Turn the pile to generate heat throughout for proper sterilization.
  • Always follow directions on both synthetic and natural pesticide products.
  • Watch for high populations of caterpillars, aphids, spider mites, thrips, scales, and other insects on plant material in the garden and landscape and treat as needed. (EPP-7306)
  • Water all plants thoroughly unless rainfall has been adequate. It is better to water more in depth, less often and early in the morning.
Lawn & Turf
  • Winter annual weeds like Poa annua, better known as annual bluegrass, and chickweed and henbit can be prevented with a preemergence herbicide application in late August. Water in the product after application. (HLA-6420)
  • Areas of turf with large brown spots should be checked for high numbers of grubs. Mid-to-late August is the best time to control heavy white grub infestations in the lawn. Apply appropriate insecticide if white grubs are a problem. Water product into soil. (EPP-7306)
  • Tall fescue should be mowed at 3 inches during the hot summer and up to 3½ inches if it grows under heavier shade. (HLA-6420)
  • For areas being converted to tall fescue this fall, begin spraying out bermudagrass with a product containing glyphosate in early August. (HLA-6419 and HLA-6421)
  • Irrigated warm-season lawns can be fertilized once again; apply 0.5 lb N/1,000 sq ft in early to mid August.
  • Brown patch of cool-season grasses can be a problem. (HLA-6420)

Protect Your Home from
Wildfire with Firewise Plantings

By David Hillock

Wildfires have been raging in the western state but luckily, we have been blessed with good rainfall to keep things relatively green; however, weather can always change and become hot and dry, and we are no strangers to wildfires. Even winters can be very dry increasing the potential for wildfires. Lives, homes, livestock, pastureland, crops, and thousands of miles of fencing can be lost to the flames.

Although a wildfire does not discriminate among its victims, there are some steps homeowners can take to help protect their property from fire, whether it be a wildfire or an accidental fire at home caused by a charcoal grill during a cookout.

The key to keeping a fire at bay is to not provide fuel for the fire.

There are plants and shrubs available that are more fire-resistant than others. 

Fire-resistant plants are those that don’t readily ignite from a flame or other ignition sources. Although the plants themselves can be damaged or killed by a fire, their foliage and stems don’t significantly contribute to the fuel and, therefore, the fire’s intensity.

Seeing a need for information for homeowners, several agencies, including Oklahoma State University Cooperative Extension, joined forces in the early 1990s and coined the term Firewise. This became a catalyst for educational resources and programs to help homeowners, communities, and firefighters to make sensible choices in the wild land/urban interface, which would in turn help control wildfires and protect property.

When selecting plants to include in a Firewise landscape, homeowners need to identify plants with a low flammability rating for areas nearing the home. By selecting plants with certain characteristics, you can reduce the flammability potential of your landscape and provide habitat for wildlife. There are several factors that influence the fire characteristics of plants, including plant moisture content, age, total volume, dead material, and chemical content.


Plants with low flammability don’t accumulate large amounts of combustible dead branches, needles or leaves as they grow. They also have little dead wood and tend not to accumulate dry, dead material within the plant. They have open, loose branches with a low volume of total branches. Many of our deciduous trees and shrubs are fire resistant. 

Leaf characteristics is something else to consider. Leaves that are moist and supple, such as the sedum leaf, are more resistant to fire.

Many herbaceous perennials make excellent Firewise plantings. Some remain green in the winter, which in turn reduces their flammability.

Oils and resins found in the sap of some trees and plants such as pine, juniper, cedar, and Yaupon holly, makes them extremely flammable. Homeowners who want to use these plants and trees in the landscape should avoid placing them adjacent to their homes and other structures on the property.

In addition, plants that accumulate dry or dead material such as twigs, needles and leaves should not be planted against the house. This includes many vines like trumpet creeper and ornamental grasses. In winter, these plants have large amounts of dry material and are extremely flammable, allowing a wildfire to spread rapidly.

As you plan out a new landscape or add to an existing one, be sure to consider fire potential in your plant selections. For more information on Firewise, please visit www.firewise.org.

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