Photo by David W. Marshall: ‘Seville’ St. Augustine is one of our most shade-tolerant lawn grasses. But even it won’t grow in dense shade.
February 28, 2014
By David Marshall
Spring is just around the corner, so that means it’s time to start getting the lawn back in shape for another growing season. If you fertilize your lawn, be careful not to jump the gun and fertilize too early, though. Wait until at least mid-March to fertilize. Even early April is okay for centipede lawns.
So what do you need to do meanwhile? Mow the lawn to get all those tree leaves off and knock back any weeds that may have popped up in it. If you have shaded areas under trees where the grass isn’t growing, now may be the time to face the fact you’re not going to get grass to grow in those areas. Just leave the natural tree leaf mulch there and add additional mulch.
If you insist on trying to grow grass in the shaded areas, spring is a good time to plant some grass plugs. All our southern lawn grasses prefer full sun, but some St. Augustine cultivars such as ‘Seville’, ‘Delmar’, and ‘Captiva’ will tolerate some shade. Trying some plugs of ‘Seville’ St. Augustine, available at local garden centers, is a low-cost way of determining if you have enough sunlight to grow grass. If the plugs don’t take hold and spread, then you probably don’t have enough sunlight and must use groundcovers, mulches, or other plantings in the shaded areas.
When you mow the lawn, don’t mow too low. Try to never remove more than one-third the length of the grass blade at any one mowing. Sharpen the mower blades after every four to eight hours of mowing so you won’t have a ragged cut. Maintain St. Augustine grass at about three inches tall and centipede at about one and one-half inches.
Most of the weeds that you will see in your lawn now are probably winter annuals. They will be growing like crazy in early March. But then they will flower, go to seed, and die as the weather gets hotter. It’s difficult to kill these winter annuals at this mature stage, so don’t try applying a herbicide now. The best thing you can do is just keep the weeds mowed so that they don’t produce so many seed and cause you a problem again next year. If the weeds that appear in early spring really bother you, then remember to put out a pre-emergent herbicide for them next October.
If you usually have a big problem with weeds in the summer, though, mid-March is the time to put out a pre-emergent herbicide for most of these summer weeds. The easiest way to apply this herbicide is with a weed-and-feed fertilizer. Be sure to select a weed-and-feed that has the right type of fertilizer. Many national brands don’t have the right type of fertilizer for our area. Some of our local nurseries, though, have fertilizers blended and packaged under their store brand for local conditions.
Unless you’ve had a soil test showing that your lawn needs phosphorus, the best fertilizer to use on lawns in our area is 15-0-15. The best 15-0-15 fertilizers have half of the nitrogen (7.5%) in a slow-release form. Local garden centers have these 15-0-15 fertilizers with and without herbicide. If you use the 15-0-15 fertilizer without herbicide,
use it at the rate of six and a half pounds of fertilizer per 1,000 square feet of lawn. If you use the 15-0-15 fertilizer with herbicide, follow the label directions. After applying fertilizer, lightly water the fertilizer in with about one-quarter inch of water.
I have discussed weed control in this column because I know that many of you have questions about weeds. Keep in mind, though, that weeds are opportunists. They sprout up in areas where your lawn isn’t growing well. So rather than be so concerned about killing the weeds, be more concerned about why the grass isn’t growing well. For example, if the soil is too compacted, too wet, too dry, or has nematodes, certain weeds may grow better in those conditions than does your lawn grass. If you don’t correct the growing conditions, you may be better off just mowing the weeds than trying to have a completely weed-free lawn. Many weeds don’t look that bad when mowed. In fact, some weeds such as dichondra are sold as groundcovers in other parts of the country.
There may be times this spring that you need to water your lawn. But don’t water when you don’t need to. Only water when about thirty percent of the lawn wilts, turning that dull grayish color as the leaf blades roll inward. But then water deeply, applying about one-half inch of water as measured in cans placed in the sprinkler pattern.
David W. Marshall, Extension Agent Emeritus with University of Florida IFAS Leon County Extension, is currently a landscape consultant with Esposito Garden Center and is author of the two-volume book set, Design & Care of Landscapes & Gardens in the South. He currently is a member of the Leon County/UF IFAS Extension Urban Forestry/Horticulture Newspaper Column Working Group. For more information about gardening in our area, visit the UF/ IFAS Leon County Extension website at http://leon.ifas.ufl.edu. For gardening questions, email us at Ask-A-Mastergardener@leoncountyfl.gov