By Charles Lillard
Oklahoma County Extension Master Gardener
There is a tendency in late summer to ease up on maintaining the lawn. Some will be cutting back on mowing, watering, fertilizing and generally let their lawn go. While there may be reasons for cutting back on watering, your lawn needs special care during this time. Now is the time to start the winter hardening process.
Letting grass grow too high between mowings can cause plant stress and affect the vigor and appearance of a lawn the rest of this year, and even into next season. It is suggested that you mow your bermudagrass no lower than 2 inches during the fall to allow for winter hardening. But remember that no more than one-third of the grass leaf area should be removed in any one mowing. This means that if your cutting height is 2 inches, your maximum height would be 3 inches. Frequent clipping will favor your grass plants.
Scalping a lawn by mowing too short or not mowing often enough causes stress and promotes thinning of the turf. A thin turf invites weeds to invade. Mowing at a recommended height and with proper frequency encourages vigorous, dense, competitive turf that maintains a better appearance. By this time in the season it could be that mower blades may be getting dull. Mowing with a dull blade or improperly adjusted equipment can give an uneven cut, bruise leaf tips and increase stress on plants.
The last nitrogen fertilizer application of the year for warm season grasses should be no later than Sept. 15. Winter broadleaf weeks like dandelions will begin to emerge in late September, which is the best time to control them with an application of herbicide. If pre-emergent control of winter annual weeds (henbit, chickweed, annual bluegrass) is desired in lawns, the application should be completed by the second week in September. Remember do not treat areas that will be seeded in the fall. Mid to late August is the best time to apply an insecticide for effective white grub control. Follow instructions on insecticide product for watering schedule. Keep children and pets off treated lawn areas until the product is watered in and the grass has dried.
What about the clipping? Should you bag them or leave them?
Regular clipping encourages individual grass plants to thicken and provide a good, uniform appearance. But what is the best way to dispose of the clippings? If bagged and carted away for disposal, the yearly cost may be more than you think. Some cities now will not take clippings as part of the trash pickup.
As we have said earlier, a good rule of thumb for mowing home lawns is not to remove any more than one third of the leaf surface area at any one time. If this is followed, you no longer need to bag your grass clippings. Leave the clippings on the lawn for their fertility value. You may want to spread out the clippings using a rake.
What about letting your lawn go brown if rainfall is short?
Water restrictions may affect how you are able to treat your lawn. Most turfgrass cultivars will survive drought conditions. As moisture stress develops, bermudagrasses and tall fescues will wilt, foliage turns blue-green, and then brown. As turfgrass go dormant, their life processes are concentrated in the crown, a unique part of the plant located between the roots and stems. As long as these areas are protected, all is well.
If allowed to go dormant naturally, turfgrass will resume growth when moisture is available again.