The Garden Guru: Pre-fall tasks to take care of the lawn

Posted Friday, Aug. 30, 2013  comments  Print Reprints

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The first week of September is the watershed week in the life of your lawn. At least for the following 12 months. Perhaps you’ll agree when you glance through these few simple facts.

Prevent winter weeds

Reach way back in the memory to those late-winter days when your lawn was plagued with a little clumpy grass with maybe a thousand seed heads per clump (give or take just a few). That was (and will be!) annual bluegrass, Poa annua. It seems harmless enough when its tiny seeds start to sprout in late September, but you’ll come to hate it by March.

Your only cure for this problem is prevention. And the only way to prevent it is to apply a pre-emergent weedkiller to kill the seeds as they begin to germinate. The two products that you’ll see most commonly in local nurseries will be Dimension and Halts, and your nurseryman will direct you right to them.

Oh, and don’t be surprised if they’re labeled as “crabgrass preventers.” That’s how the majority of these products get sold, so play along with the game. Crabgrass prevention time will come in the spring, but the same active ingredients will work handsomely at preventing annual bluegrass, rescuegrass and ryegrass right now. Apply the granules the first week of September and water your lawn immediately after.

There is another group of winter weeds that can also be prevented by an early September treatment, and that is the nongrassy bunch known as broadleaf weeds. That includes dandelions, clover, henbit and chickweed, among scores of others. Gallery herbicide must also be applied before the seeds start to sprout. It can even be applied the same day you apply your other pre-emergent for grasses, but don’t try to mix the granules.

For the record, pre-emergent weedkillers are cleared for use on any type of lawn grass, and they won’t harm trees and shrubs. But don’t use them on young lawns that haven’t gone through their first winters.

Time for final feeding

Turf experts tell us that the fall feeding is the most critical fertilization of the year. It spurs new growth in fall’s better weather, but it also toughens the grass for a quick start come spring.

In Blackland Prairie clay soils, tests almost always show that you should apply an all-nitrogen fertilizer. It seems that clays hold phosphorus to the point of excess. Soil tests done on sandy soils of the Mid-Cities commonly show the need for a high-nitrogen product such as 20-5-10 or 24-6-12 (or some similar analysis). Use all-nitrogen or high-nitrogen fertilizer, and buy a quality plant food that has half or more of its nitrogen in slow-release form.

The question arises: What sequence should be used in applying pre-emergent weedkillers and fertilizers? Since fertilizers should be watered into the soil deeply, and since pre-emergents do better if watered lightly, it’s best to apply the plant food, water, wait one day, apply the pre-emergent, then water lightly. If watering restrictions won’t let you do that, fertilizer and pre-emergents can certainly be applied on the same day. Just don’t water so heavily that there is runoff.

Last call for new plantings

This is the only time of the entire calendar year when all types of turfgrass can be planted. If St. Augustine is your choice, the sod must be laid in the next couple of weeks (sooner is better than later) to ensure that it has time to develop good roots before winter. Strange as it seems now, we’ve had killing frosts as early as two months from this weekend. Bermuda and zoysia sod can be planted into mid- and even late September, but if you’re seeding new Bermuda, you need to get busy.

If you happen to have fescue as your permanent turf, since it’s a bunch grass (forms clumps, but no runners), you’ll want to overseed it each September to keep it dense. Sow at 4 to 5 pounds per 1,000 square feet. In that case, seed by mid-September, but do not use a pre-emergent weedkiller this year.

Some people cover-seed their lawns with perennial ryegrass (not really “perennial” in Texas). Those plantings need to be made by mid-September, and again, no pre-emergents this year, please.

Spruce up what you have

Most area lawns look a little rough by late summer. Keep a close eye out for dried St. Augustine in hot, sunny areas, because those are symptoms of chinch bugs. Once you’ve made sure they’re the source of your problems, Imidacloprid insecticide will stop further damage.

A few local lawns are also showing the horrific impact of Pythium, also known as cottony blight. It kills very defined areas of Bermuda grass quickly, almost as if someone had applied a glyphosate herbicide carelessly. Cutting back on both watering and feeding is the best remedy for this disease of overconsumption.

Neil Sperry publishes “Gardens” magazine and hosts “Texas Gardening” from 8 to 10 a.m. Sunday on WBAP AM/FM. Reach him during those hours at 800-288-9227.

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