As we move into June, let's talk about how to care for lawns during this prolonged drought.
Water restrictions remain in effect. Most areas are limited to watering one day a week. (Visit tampabaywater.com to check the restrictions in your locality.)
FIRST THINGS FIRST: Your automatic sprinkler system should deliver ¾ to 1 inch of water during each irrigation cycle. Second, proper mowing practices are essential. Mowing stresses the grass plant's metabolism, which reduces root growth. Your goal, in encouraging a healthy lawn, is to promote root growth.
Use the highest setting on the mower for conditioning your grass, because a low cutting height needlessly stresses the grass. The larger the grass leaf area, the more the plant can feed itself by photosynthesis. This results in more carbohydrates for plant growth, especially that desirable root growth.
The higher the grass is mowed, the deeper and more extensive the root system becomes.
Mowing should be done often enough to minimize the shock of cutting. Never remove more than one-third the height of the grass at any one time. If the grass is allowed to grow to 4 inches, do not mow it lower than 3 inches.
Adjust the frequency of mowing to the growth of your grass. In summer, it may be necessary to mow several times a week, but in the winter, once a month may be enough.
Keeping the mower blades sharp and properly balanced is also an important part of good mowing practices. A leaf cut by a sharp blade will recover more quickly and lose less water than a leaf blade shredded by a dull mower blade.
FEED YOUR LAWN: Proper fertilizing can increase your lawn's drought tolerance. So take a minute to understand how plants respond to the main ingredients in fertilizer, nitrogen and potassium.
All of the good drought conditioning accomplished by proper irrigation and mowing practices can be undercut by fertilizing excessively with nitrogen. Too much nitrogen encourages shoot growth and reduces root growth. Yes, the grass grows lush and green when the lawn is heavily fertilized with nitrogen, but lush leaves need more water and are much more susceptible to insect infestation.
A good lawn fertilizer will hold 50 percent of the nitrogen in a slow-release form. To green up the lawn during hot weather, use iron sulfate instead of a fertilizer containing nitrogen. The iron will green the lawn without creating the lush growth that needs additional water. Lawns should never be fertilized to deepen the color, since Southern turf grasses, except Bermuda, are often more of a yellowish-green.
Potassium fertilization can help turf grasses increase their tolerance to stress. Potassium promotes increased root growth (again, your main goal) and thicker cell walls, both signs of drought tolerance. Turf grasses require potassium in nearly the same amount as nitrogen, especially in sandy soils where both can readily leach out. A fertilizer with a 15-0-15 analysis and at least 30 to 50 percent of the nitrogen in a slow-release form is a good choice.
Other macro and micronutrients, as well as the soil pH, should be kept at recommended levels for optimal growth.
SEED YOUR LAWN: The best time to seed Bahiagrass is after the summer rains begin. Bahiagrass seed is very large, and you'll need 5 to 10 pounds to cover 1,000 square feet. The lawn should be moist and level. Rake or cover the seed in the soil to a depth of one-quarter to one-half inch. Keep it moist until germination occurs, which may be three weeks or more. If the soil is allowed to dry out after the seeds have started to swell, many of them will die.
DE-PEST YOUR LAWN: Dingy brown moths flying around grassy areas are often an indication that the sod webworm is laying its eggs. In five to seven days these eggs hatch into small green caterpillars. Injured grass has notches chewed along the sides of the blades. The foliage may be completely stripped in patches.
A soap flush is a good way to detect webworms. The soap is an irritant that causes the insects to surface. Put 2 tablespoons of dishwashing liquid into a 1-gallon sprinkler can. Fill with water, and drench an area 4 feet square. Observe for about two minutes to see if webworms surface.
Pesticides labeled for sod webworm control are Bacillus thuringiensis (Bt, Dipel, Thuricide) and Carbaryl (Sevin). Bt is a bacterial product that will cause the caterpillars to stop feeding and die, without harming beneficial insects (except butterfly caterpillars); it's also safe for wildlife, pets and humans.
Sod webworms may reinfest the lawn within one to three weeks after treatment. Reapply pesticide as required.
Compiled by Pam Brown and Carol Suggs of the Pinellas County Extension Center/Florida Botanical Gardens. Questions: (727) 582-2100.