What to Use on St. Augustine for Weed & Feed?

Description

• St. Augustine grass is a coarse, thick-growing grass that spreads from stolons. With frequent mowing, the grass produces a dense mat of foliage suitable for lightly used lawns. The blades are folded and slightly rounded on the tips. The flowers are spiked racemes in groups of up to three. The blue-green color is deepest in humid areas where it receives adequate water. St. Augustine grass tolerates short periods of drought, but terminal leaf damage may result. The grass is difficult to start from seed and is primarily propagated from sprigs, plugs or sod.

Varieties

• St. Augustine grass thrives in full-sun areas, but some varieties have increased tolerance to shade. Delta Shade, Bitterblue and Classic have good shade tolerance. The dwarf varieties all do well in shade and include Captiva, Delmar, Seville and Sapphire. Chinch bugs are main pests of the grass and varieties are being researched that have some resistance to the insect. Floratam and Seville have a limited resistance, but other varieties are still plagued by the insect. Many cultivars were bred to resist Brown Patch Disease, which opens up areas in the sod for weed formation and ruins the lawn's appearance.

Maintenance

• Well-tended grass has fewer weeds and pest problems. All grasses need nitrogen as a primary food source. A pre-emergent weed-and-feed supplies early grass blades with important sources of nitrogen and applies an herbicide preventing spring weeds from sprouting. Chose a pre-emergent weed-and-feed that is approved for use on St. Augustine's grass according to the product label. Apply it in very early spring when temperatures reach 60 degrees for at least four days. A product with imazaquin is useful for nutsedge and many other common grass invaders. Atrazine is another herbicidal chemical found in a weed and feed, but it is toxic.

Problems

• Weed-and-feed is a good idea, but its use means one of the components is being applied at the wrong time. Food for grass is generally applied as it greens up or leaves dormancy. You can even feed the lawn during the green period, although it means frequent mowing. Weed suppressions are best applied before the weeds seed in late summer or fall. If you wait until spring, some of the broadleaf weeds are emerging and a pre-emergence herbicide is no help. You can't use most post-emergence products on St. Augustine grass because it is sensitive to that herbicide. Feeding, mowing and irrigating at proper levels develop a thick, healthy lawn that doesn't allow weeds to grow.