Taking proper care of your lawn in the fall keeps it healthy and prepares it for the winter months ahead. There are a number of steps you can take to ensure your lawn’s winter survival and a strong recovery in the spring.
In the fall, apply a quick-release fertilizer at least six weeks before the first expected frost. You’ll need to water it in with irrigation after application. The nutrients from the fertilizer will increase lawn density, improve color, help prevent winter weeds, and provide enough stored sustenance to aid growth in the spring.
Warm-season grasses, such as buffalo, bermuda, St. Augustine, and zoysia, go dormant when the temperature drops below 60°F on a regular basis. Because of this factor, fertilizers for warm-season grasses in the fall should not be high in nitrogen (N). Too much nitrogen at this time can over-stimulate growth when the grass should be preparing for dormancy, making it vulnerable to frost and possibly winter kill.
A high nitrogen content in the fall also provides energy for winter weeds, as well as disease such as Large Patch, a fungus that becomes active when temperatures drop, and moisture and heavy nitrogen levels are present.
Warm-season grasses also benefit from a late-season fertilizer containing potassium, especially if soil test results indicated low amounts. Potassium helps grass resist disease and endure cold temperatures.
Fall pre-emergent herbicides should be applied when soil temperatures reach approximately 70°F. This won’t necessarily occur at the same time every year, as environmental conditions differ year to year. To help determine the correct application time, homeowners can use soil temperature probes, probe-type meat thermometers, or soil temperature maps.
Choosing the right herbicide is less challenging if you know what grassy and broadleaf weeds you’re dealing with. Products usually list the range of plants they control, and whether they’re annual or perennial. The pre-emergent herbicides are most effective on annual weeds, while post-emergent herbicides are needed for perennials. In some instances, it’s better to apply both pre- and post-emergent herbicides at the same time, especially if homeowners are splitting their pre-emergent application over a couple of months.
Granular herbicides are easier to apply for the homeowner than liquid ones. In either case, it’s important to always follow the label instructions for proper use, timing, and implementation (e.g. might need activation by irrigation or rainfall). Some pre-emergents will injure grass when applied at certain times of the year, and many are only meant for established turfgrass.
Always apply a herbicide before fertilizing. Give it a couple of days to work before applying the fertilizer.
Continue to mow your lawn to the proper height for your type of grass. The recommended cutting height for warm-season grasses varies by species. According to Texas A&M AgriLife Extension Service, the height for some of the common Texas warm-season lawn grasses are as follows:
- Bermuda (common) — 1.5 to 3 inches
- Bermuda (hybrid) — 1 to 2.5 inches
- Buffalo — 2 inches
- St. Augustine — 2.5 to 4 inches
- Zoysia (fine-textured) — 1 to 2 inches
- Zoysia (coarse-textured) — 1 to 2.5 inches
It’s also recommended you keep your grass species at the taller height of the range. Generally, no more than 1/3 of the height should be removed during any one mowing. For example, if your ideal grass height is 2 inches, then you would need to mow before the height is more than 3 inches. Letting the grass get too tall before mowing can lead to scalping (the excessive removal of leafy green growth that results in injury to the grass).
A heavy build-up of leaves on a lawn not only suffocates your grass when air can’t circulate, but also blocks the sunlight, prevents water evaporation, and can attract fungus, mold, and pests.
There are a number of choices for dealing with leaves:
- Rake, pile, and bag them for collection.
- Take the raked leaves, layer them 6 inches deep in your garden and flower beds and use a tiller to work them directly into the soil.
- Use a mulching mower or mulching attachment to shred leaves into tiny quarter-sized pieces. These can decompose slowly on the lawn, adding nitrogen and organic matter to the soil.
- Use a grass catcher with your regular mower to capture the chopped-up leaves and create or add them to your compost pile.
- Place chopped up leaves from the grass catcher as mulch around trees and shrubs, and over perennial beds.
When temperatures start dropping in the fall certain warm-season grass diseases become more active. Effective grass management practices should prevent and control fungal diseases, but if specific areas of your grass have a history of disease (e.g large patch and take-all root rot) you can apply a preventative fungicide around the same time as pre-emergent herbicides.
Correct diagnosis is important for successful treatment. If you’re having difficulty identifying the disease, ask a lawn care professional, or contact your Texas A&M AgriLife Extension County Office for assistance.
This time of year, homeowners should monitor their yards for fall armyworms up until the first frost. The small larvae chew the green layer from the leaves, creating a “windowpane” effect (small areas of the leaf with no green tissue). They’re most active early in the morning or later in the evening, although they can feed at any time. Damaged lawn areas appear off-color, and eventually turn brown as entire leaves are destroyed.
Treat your lawn when leaf damage is visible or you can see large numbers of caterpillars (larvae). Conventional treatments for armyworms in lawns include such insecticides as bifenthrin, carbaryl, esfenvalerate, and permethrin.
Early fall is also a good time to inspect your lawn for visible signs of grub damage. The grubs are now in their late larvae stage and will continue to attack the grass roots until the cooler weather, at which time they’ll move below ground and go dormant until spring.
Irregularly-shaped dead patches can be one sign of a grub infestation, especially if one or more of those patches easily peels away because there are no roots. Animal life digging tunnels or stripping away your grass is also another possible sign.
To be certain, dig several areas of your lawn 1 foot square and 4 inches deep, and peel them back. If you see 10 or more grubs per square foot you need to treat your lawn.
The curative treatments carbaryl and trichlorfon are the chemicals to use in the fall for grubs. They’re short-lived products that kill all grub life stages. Apply them in September or late October. The following June and July you’ll need to treat again, this time with preventive insecticides to protect against the next generation of grubs.
Homeowners with bermuda grass who want a green lawn during the winter can overseed with a cool-season ryegrass. Overseeding is not recommended for other warm-season grasses.
According to turfgrass specialists at Texas A&M AgriLife Extension Service, fall overseeding is done mid to late October and early November. Bermuda grass should be dormant by then, so the ryegrass won’t compete with it for nutrients and sunlight.
Varieties of perennial and annual ryegrasses are most commonly used for overseeding. Perennial ryegrass is often preferred because of its slower growth, disease resistance, less mowing time, and superior dark color. However, annual ryegrass is less expensive, germinates 3 to 8 days faster, and dies out more quickly in the spring so the bermuda grass can regrow without competition.
If you are overseeding with winter ryegrass here are some guidelines:
- Generally, don’t apply a pre-emergent herbicide within 6-8 weeks of overseeding. Read the label for specific instructions on the timing.
- You may have to apply a starter fertilizer before or right after seeding, especially if a soil test indicates low phosphorus (P).
- Mow the lawn to the lowest height in the recommended range for your type of bermuda grass.
- Dethatch if there’s more than 1/2 inch of thatch so the grass seeds can reach the soil evenly everywhere. Use a dethatching rake for small areas, and power-driven equipment for large areas (rent or hire someone).
- If aeration is necessary, irrigate heavily the day before, or a day after a rainfall, so the soil is moist. Then wait 30 days before overseeding to allow the holes time to heal.
One of the most effective things you can do to maintain a lush, healthy lawn and garden is to keep your irrigation system at peak operating efficiency. South Austin Irrigation can provide custom scheduling, controller replacement and upgrades, system upgrades, leak detection and repairs and many other. Call us at (512) 534-7449 or fill out our online service request form.