Gardening: The heat is on, so your lawn needs special care
The heat is here, which means a little more maintenance - especially mowing.
Good mowing practices are an important key to a healthy lawn and often go overlooked. Improper mowing can lead to thatch buildup and an increase in disease, insect and weed problems.
DON'T 'SCALP'
One of the biggest mowing mistakes made by homeowners and commercial landscape maintenance companies is cutting a lawn too short, referred to as "scalping." Mowing height differs by grass type and variety. The mowing height for bahia grass is from 3 to 4 inches, bermuda grass from 0.5 to 1.5 inches, centipede grass from 1½ to 2½ inches, St. Augustine grass from 2 to 4 inches and zoysia grass is from 0.2 to 2½ inches.
Note the large mowing height range given for St. Augustine grass and zoysia grass. That's because varieties have different growth habits that relate directly to mowing heights.
For example, standard St. Augustine grass varieties should be mowed at 3½ -4 inches and dwarf varieties like Seville, Captiva and Delmar at 2-2½ inches. Lawns mowed at the proper height develop a stronger root system and help shade out unwanted weeds. Another way to avoid scalping is to change the mowing direction each time you cut the lawn.
THE ONE-THIRD RULE
Never remove more than one-third of the grass height. Removing too much at one cutting will stress the lawn and contribute to thatch problems. For example, if you are maintaining St. Augustine grass at 3 inches, it should be cut when the grass reaches 4 to 4.5 inches.
KEEP BLADES SHARP
Keep lawn mower blades sharp. Grass blades are wounded when cut and heal quicker from a clean cut versus a jagged cut. Lawns cut with a dull mower develop a brown appearance because the grass blade actually is torn, not cut. This creates more stress for the lawn and makes it more susceptible to disease and insect problems.
DROUGHTS HURT
Avoid mowing the lawn when it is under severe drought stress. Lawns go into dormancy during droughts, become brittle and are more prone to bruising especially from the weight of heavy mowers. To prevent this from happening, mow the grass after a rainfall or after your irrigation day.
WET OR DRY?
Never mow the lawn with a rotary mower when it is wet. Clippings from wet grass will clog the lawn mower causing an uneven cut and will clump more potentially creating a thatch problem.
DON'T BAG CLIPPINGS
Let clippings fall back on the lawn instead of bagging them. As long as the grass is cut at the proper height, this will not create a thatch problem but will provide a slow-release fertilizer to the lawn. If grass accumulates in clumps, use a leaf rake or blower to disperse. On average, as the clipping decompose, this contributes 1 pound of nitrogen per 1,000 square feet per year.
When mowing, aim grass clippings back onto the lawn and away from streets, storm drains or bodies of water. Either blow grass clippings back onto the lawn with a blower, or sweep/vacuum to remove them from streets, sidewalks or driveways.
If mowing near water, bag the grass clippings within a 6-inch area bordering the water to reduce nitrogen content in our water bodies. Also, keep grass clippings away from storm drains to prevent clogging.
HOT? FERTILIZER NOT
If the lawn is growing too quickly, don't apply nitrogen fertilizers during hot summer months. Instead, if the lawn needs greening up this summer, apply iron sulfate or a chelated iron source. Apply iron sulfate at the rate of 2 ounces per 3 to 5 gallons of water for every 1,000 square feet and repeat every six weeks if needed. This is especially important if the soil pH is alkaline (over 7.0) or if the water source is alkaline.
Another option for greening up lawns is to apply manganese sulfate at the rate of 0.41 pounds per 1,000 square feet (18 pounds per acre).
IRRIGATION TIPS
Lots of water will cause excessive growth. We have no control over rainfall but we do over irrigation. If the lawn is receiving adequate water from rainfall, cut off the irrigation system.
Signs of a thirsty lawn are grass blades that fold, grass color will change from green to bluish gray, and footprints or tire-tracks remain in the lawn (doesn't bounce back). When you do irrigate, make sure to apply between ½-¾ inch of water to encourage a deep root system that is more drought- and cold-tolerant.
AND THE GOOD NEWS...
Take advantage of checking the lawn for problems when you mow. And if it makes you feel any better while mowing the grass this summer, you're burning calories. A 155-pound person burns 387 calories per hour operating a power mower.
Terry Brite DelValle is a horticulture extension agent with the Duval County Extension Service and the University of Florida/IFAS.