Most-asked lawn questions for the summer

Posted Saturday, Jul. 13, 2013  comments  Print Reprints
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I get a lot of repeat questions on lawns in the summertime. Here are some of the ones that I’m hearing most frequently this year.

Can my lawn survive with the water curtailments?

Yes, absolutely. Unless your curtailments call for absolutely no watering, you can keep the lawn going with weekly watering. It may not be lush and green, but it will survive to see a better day. Water deeply when you do water, to encourage deeper roots. That’s important when you have long periods of drought.

How long should I run my sprinklers on the grass?

There is no answer to that question, because there are so many variables. Sun or shade? Sand or clay? Slope or flat? What types of plants are you watering? The best answer is that you should water deeply when you do water. Those thorough waterings will encourage all plants to develop roots farther down into the soil.

Should I fertilize my lawn during the summer? If so, what should I use?

Perhaps, depending mostly on the type of grass that you’re growing and the water you’re allowed to provide during this summer of cutbacks. Bermuda should be fed every two months, April through early October. It’s generally better not to feed St. Augustine between mid-June and early September, because nitrogen increases the likelihood of your St. Augustine developing gray leaf spot. There is no effective fungicide for the disease, so avoiding nitrogen at this time of year is your best remedy.

Can I start new grass this time of year?

Yes. In fact, the sooner the better. For St. Augustine and Bermuda, early September is just about your final chance. The closer you get to that date, the bigger the likelihood of its suffering cold-weather damage. You’ll have to water the new grass every day, perhaps twice per day, to keep it from drying out before it can form good roots. You don’t want it to be waterlogged, however, so you probably only need to let the sprinklers run for 5 to 8 minutes per area per time. After a couple of weeks, you can increase the amount of water you apply while you increase the time between waterings.

Why do I have dry patches in my St. Augustine?

It could be from a sprinkler head that isn’t delivering water properly and uniformly. However, it’s also very likely that it’s chinch bug damage. They will attack St. Augustine in the hottest, sunniest parts of your yard (never in the shade). The grass wilts, yet it does not bounce back when it’s watered. You can see the small black insects with irregular white diamonds on their backs if you look closely into the boundaries of the dying grass in mid-afternoon on a sunny, hot day. Part the grass with your fingers. If you see the pests, apply Imidacloprid insecticide at once. Chinch bugs can kill St. Augustine in just a few days.

My Bermuda lawn has irregularly shaped dead areas several feet across. It looks like someone has poured gasoline on the areas. What did that?

If the patches are extremely pronounced, and if they develop quite suddenly, your turf may be suffering from Pythium fungus. It’s most commonly seen in parts of the lawn that are watered and fed to excess. Fungicides may help a bit, but you should also cut back on the water.

My St. Augustine has runners that are on top of the lawn. It looks like their roots have died. What causes that?

While I don’t have a precise name for the fungus that causes that, it’s about as harmless as any problem can be. The simplest cure: Kick up the affected runners with your shoe soon before mowing. The lawn mower will cut and remove them, and the problem will abate within a week or two. There is no other call to action.

What is the ugly, weedy grass that makes dense clumps and sends up seed heads almost immediately after the lawn has been mowed? How do I get rid of it?

Dallisgrass. Its clumps are dark green and the size of a dinner plate. As you mentioned, it starts sending out seed heads almost as soon as you can remove the old ones. And, worst of all, every seed that forms will be viable. They do not require pollination. If you see dallisgrass getting a start, hand-dig it immediately. You could also spot-spray with a glyphosate-only herbicide. While it will kill the dallisgrass, it will also kill your desirable turfgrass, so you need to be precise in how you apply it. Someone recently suggested cutting the bottom out of a 1-gallon plastic milk jug, then placing it atop the dallisgrass clumps as a baffle to the spray. Insert the spray nozzle into the top of the jug, then spray the weed. You’ll make a precise application and avoid drift onto nearby turf. The good news is that glysphosates do not contaminate the soil, so new grass can start growing immediately.

How can I get rid of nutgrass?

Note that this weed is not actually a grass, but a sedge (triangular stems versus the round stems of all grasses). Grass killers don’t work on it. Best controls for nutsedge include the original Image or SedgeHammer. Begin your treatment at once, because nutsedge goes dormant as it turns cool in mid-fall. Hand-digging is not a reliable means of controlling this pest.

Neil Sperry publishes “Gardens” magazine and hosts “Texas Gardening” from 8 to 11 a.m. Sundays on WBAP AM/FM. Reach him during those hours at 800-288-9227 or 214-787-1820.

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