Taking care of your lawn in the fall prepares it for a dormant winter and gives it the best chance for a quick green-up in the spring. Here are some lawn care tips that will keep your lawn healthy throughout the fall and winter months.
All turfgrasses have low and high optimum mowing heights that vary with grass types and cultivars (varieties of a specific plant created from a natural species and maintained by cultivation). Continue mowing to the proper height for your warm-season grass type until it goes dormant (when soil temperatures remain consistently below 55°F).
Texas A&M AgriLife Extension Service recommends the following mowing height ranges for common Central Texas warm-season grasses:
- St. Augustine — 2.5 to 4 inches
- Bermuda (common) — 1.5 to 3 inches
- Bermuda (hybrid) — 1 to 2.5 inches
- Buffalo — 2.5 inches to 4 inches. Can leave unmowed in natural areas
- Zoysia (coarse) — 1 to 2.5 inches
- Zoysia (fine) — 1 to 2 inches
If winter annual or perennial weeds appear, mow the lawn regularly to keep the weeds under control over the winter months.
With cooler fall weather your lawn needs less water than in the summer. Use the controller’s “seasonal adjust” feature to change the zone run times to a percentage of the programmed summer schedule. Your rain sensor will also shut down irrigation when it starts to rain.
Once your lawn goes dormant, continue to irrigate once or twice a month. This keeps the root cells full of water and acting as an insulator from freezing temperatures. The moisture in the soil also keeps the roots warmer and protects them better than dry soil.
Apply a quick-release fertilizer six to eight weeks before the first expected frost (four to five weeks for Bermuda grass). Irrigate to water the fertilizer in so it moves down to the roots. Use a fertilizer low in nitrogen (N). This prevents stimulation of new growth that would interfere with the grass entering its dormancy period and make it vulnerable to frost damage.
Using fertilizers with high nitrogen content in the fall also sets the stage for winter weed growth, and fungus diseases such as “large patch”. Large patch starts to develop when temperatures drop to 70°F in the fall, but symptoms may not appear until the spring when warm-season grasses begin greening up. Soil moisture from heavy rain, dew, or irrigation is also necessary for this fungal disease to develop.
Applying potassium (K) in the fall is beneficial, especially if a soil test shows low amounts. Potassium helps prevent disease and provides stress relief from cold temperatures.
Treat established lawns in the fall with pre-emergent herbicides to control annual winter weeds before they emerge from the soil. Apply when the soil temperature reaches about 70°F for 2-3 consecutive days. Use soil temperature probes, meat probes, or a soil temperature map to determine the right application time. For visible weeds, spot treat with post-emergent herbicides.
Identifying the weeds in your lawn will help you choose the right herbicide. Herbicide labels usually list the weed species they eradicate, as well as instructions for timing, amount, application rate, and turfgrass safety.
Apply herbicides before you fertilize or mow the lawn. Wait two or three days before mowing, and at least a week before applying a fertilizer. The grass needs time to overcome any stress from the herbicide.
Many warm-season lawn diseases become more active in the fall with the cooler weather (e.g., large patch, take-all root rot). The key to choosing the correct fungicide is knowing what disease you’re treating. Ask a lawn care professional or contact your Texas A&M AgriLife Extension County Office to speak to a master gardener for assistance if you’re having difficulty with identification.
Fungicides can be purchased at garden centers and nurseries, but only lawn care professionals have access to some of the more effective ones. You can apply fungicides at the same time as fertilizers if the fungicide is also activated by water. Fungicides can also be applied at the same time as pre-emergent herbicides.
There are certain pests that are active in turfgrass in the fall:
- Appear especially after early fall rains, and are active until the first killing frost.
- Feed primarily early in the morning or late evening, although they can feed at any time when there are cooler temperatures and cloudy skies.
- Small larvae (caterpillars) chew the green layer of turfgrass blades, leaving a clear “windowpane” effect.
- Damaged lawn areas will appear off-color, and eventually turn brown as all leaves are destroyed.
- Treat quickly when leaf damage is visible, or if you see three or more caterpillars per square foot (1/2 inch or longer) — they can destroy a lawn within a few days.
- Choose a chemical control available to homeowners (e.g., carbaryl, chlorantraniliprole, bifenthrin, permethrin) or call in a lawn care professional.
- Non-toxic options are also available (e.g., Bacillus thuringiensis (Bt), Spinosad, pyrethrin).
- Late larval stage feeds on grass roots until the temperature drops (end of October), and they move below ground and go dormant until spring.
- Look for irregularly-shaped dead grass patches, dead patches that peel away easily because there are no roots, and animals digging tunnels or stripping away your grass.
- To confirm a grub infestation, dig up small sections of dying grass, and peel them back. If there are 5-10 or more grubs per square foot, treat your lawn.
- Carbaryl and trichlorfon are short-lived products that kill all grub life stages — apply in September and late October.
- Apply a preventive insecticide the following June and July.
- Use insect-killing nematodes as an organic option.
Homeowners with Bermuda grass who want a green lawn throughout the winter can overseed with a temporary annual or perennial cool-season ryegrass. This is done from mid-October to early November after the Bermuda grass has gone dormant.
An established winter lawn requires the same maintenance as a permanent lawn:
- Irrigate regularly.
- Mow the ryegrass to the lowest recommended height for the Bermuda grass. Annual ryegrass has to be mowed more often than perennial.
- Apply post-emergent herbicides to control weeds once the ryegrass is established and has been mowed a few times.
- If ryegrass growth and color need maintenance, apply a high-nitrogen fertilizer midwinter.
Keep your lawn free of leaves so it can breathe and carry out photosynthesis. Rake the leaves or use a grass bag when mowing to capture them. You can also use a mulching mower that shreds the leaves into tiny pieces (about the size of a dime) on the lawn, where they’ll decompose and provide nutrients to the soil. A regular mower will also do the job, although it may take more than one pass to get the shreds to the desired size.
South Austin Irrigation are the experts in irrigation system troubleshooting and repair. Call us at (512) 534-7449 or contact us online to keep your sprinkler system operating at peak performance.