Gardening plus Texas summers equal a ton of questions.
Here are the ones I hear everywhere I go.
How can I get my lawn to fill in the voids a little more quickly? Determine the reason for the voids. If they're due to excessive shade, you must either remove a low-hanging branch or two or switch over to a more shade-tolerant ground cover. If the bare spaces were caused by last summer's drought, transplant sod from within your own yard. Keep it moist at all times, and it will recover quickly. Seeding Bermuda into small portions of an established lawn is not a good plan.
When should I fertilize my lawn, and what fertilizer is best? Assuming you applied a lawn food coming out of the winter, it's time to feed it again. Unless a soil test indicates otherwise, use an all-nitrogen product that has half or more of its nitrogen in slow-release form. Repeat the application in early August and again in early October for Bermuda turf and in early September for St. Augustine.
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What is the clumping, weedy grass with deep green leaves, and how can I control it? That sounds like dallis grass. You can confirm its identification by looking at its seed heads. Dallis grass produces flat, disclike seeds with black, peppery specks. The seed heads will develop just a few days after each mowing. We have no selective herbicide that will kill dallis grass within St. Augustine or Bermuda turf without harming the "good" grass. That means you'll either have to remove the clumps manually, probably using a sharpshooter spade, or apply a glyphosate-only herbicide specifically to the clumps. It will kill all grasses on which it's sprayed, but the soil will not retain any residue, so new grass can cover back in very quickly.
What should I do now with my Knock Out roses, since they're no longer blooming? Remove the old flower stalks. Prune the stems back by 25 or 30 percent, to reshape them and to keep them from getting too tall and unruly. That pruning will stimulate strong regrowth, and that will give better blooms during late summer and all the way through fall.
Why are my trees losing big pieces of bark? With all the spring rain, many of our shade trees have grown vigorously. Bark is a dead tissue, so it cannot expand as a tree's trunk grows thicker -- it will separate and slough off. If it's specifically on oaks, it's possible that Hypoxylon canker is involved. Oaks under stress of heat and drought are rendered more vulnerable. That's the time to call in a certified arborist.
Why are my red oaks dropping so many leaves? That's a form of anthracnose. It's not what you'd wish for your trees, but arborists assure us that it's no reason for concern. The affected leaves will be replaced by healthy new growth.
What should I do for bagworms this year? Watch your plants very closely and start checking them immediately -- the bagworms are already active. Last year was horrible for them. There's no telling how bad they'll be this time around, but you should inspect coniferous evergreens such as junipers and cypress closely. Almost any insecticide will kill the larvae when they're young and mobile. Take care of them before they strip your plants bare.
Why aren't my crape myrtles blooming, when all the others on my block already are? It could be genetic. Some varieties are known to start blooming six or seven weeks earlier than others. Or it could be because of excessive shade. Crape myrtles need full or nearly full sunlight to bloom to their potential. It could also be because of winter pruning. Plants that are "topped" will be six to eight weeks late in their first bloom (yet another reason never to top crape myrtles).
Why are my tomato plants turning brown? That's most likely because of spider mites. This is the time that mites typically start to show up, but because of the warm May, they've already been active for several weeks. Thump one of the yellowed leaves (as opposed to one that's already dry) over a sheet of white paper. If you see tiny specks that start to move, apply a labeled insecticide product to control them. Be sure the spray coats both top and bottom leaf surfaces. Once the mites have made their way halfway up a plant, and especially if you're seeing fine webbing, it may be too late to turn things around.
Why are my tomatoes turning brown on their ends? You're seeing blossom-end rot. It looks like a disease, but it's actually just a physiological issue that shows up on plants that have gotten too dry between waterings. The ends of the fruit are the places farthest from the roots, so they're the parts that dry out first and receive water last. Mulch your plants, and maintain more uniformly moist garden soil. Be especially mindful of watering tomato plants that are growing in pots.
Neil Sperry publishes Gardens magazine and hosts Texas Gardening 8-11 a.m. Sundays on WBAP AM/FM. Reach him during those hours at 800-288-9227 or 214-787-1820.