Unless you are in the hay business, you should not be interested in how much tonnage of grass you can produce. As a result, lawn fertilization should not be a prime concern in mid-summer. A lawn with good color, uniform height and uniform thickness is the desired result of early season planning and care. Excess nitrogen fertilization can lead to excess growth and more frequent mowing. It can also set your lawn up for brown patch disease this fall. Leave the mid-summer for other lawn care practices that relieve plant stress during this hot, stressful period of time.
Before we leave fertilization, let me say that there are always exceptions to the rule. If your lawn was filled with clover this spring and you haven’t fertilized this year, a good application of nitrogen fertilizer will help prevent the clover for next spring. Ideally, adequate nitrogen in the early spring will provide lawn grass with the means to fill the thin spots and aggressively grow.
The clover emerges in the winter in the areas of thin turf. So, if you want to prevent clover, make nitrogen applications in the spring or, if you missed it at that time, apply it now. An application of one pound of actual nitrogen (3 pounds of 33-0-0) per 1000 square feet of lawn will stimulate the grass to be more competitive with the clover in the fall. Clover also has a habit of emerging in areas weaken by brown patch disease, so now is a better time than the fall to apply nitrogen.
For hot weather applications, a slow-release nitrogen blend is best. Avoid nitrogen applications after August. The grass needs to go slowly dormant in late summer and fall when the probability of brown patch disease development is greatest.
Mow properly. This is always the most critical practice in lawn care. Don’t mow with a dull blade. It shreds the grass leaf and makes for an uneven appearance. Don’t mow St. Augustine grass shorter than three inches tall. Centipede and Bermuda grass may be taken down lower, but not under 2 inches. Severely mown grass is stressed grass. Stressed grass is more susceptible to disease, stand thinning and weed invasion.
Weed control now is also a little tricky. Hard to control weeds, like dollar weed and Virginia button weed, can be controlled with a broadleaf weed killer like Weed-Free Zone, Trimec or Weed-B-Gon, but there may be a temporary burn of the lawn grass in hot weather. This burn is usually gone after the grass is mown.
If you need to irrigate your lawn, do so in the morning or early afternoon. Late afternoon or night irrigation encourages brown patch disease. Watering in the early part of the day will relieve the stress of heat on the grass and dry away the excess moisture that feeds the brown patch fungus at night. When needed, irrigate your lawn thoroughly once or twice per week.