St. Augustine grass is one of the five species of warm-season turf grasses that are used in Hawai'i. Each species has its own special characteristics that may make it more desirable for use in various situations. Each of the other four species has been featured in this column over the past several years.

The most significant characteristics of St. Augustine are high shade tolerance, high salt tolerance and a fairly low maintenance requirement. However, it will wear down under moderate foot traffic and tends to develop a very thick and spongy underlying thatch. It also has coarse, broad leaves, which some people find objectionable. St. Augustine grass is often called "buffalo grass," but it should not be confused with the true buffalo grass, which is a fine-textured, cool-season prairie grass. The Hawaiian name for St. Augustine is manienie haole or 'aki'aki haole.

St. Augustine grass is widely adapted to subtropical regions. It is one of the most commonly used turf grasses in urban and coastal areas of Florida and California. It was introduced into Hawai'i in 1816 and is often used here for commercial office buildings, shopping plazas and residences, particularly when the lawns are subjected to shade or along the seashore.

It spreads rapidly by thick above-ground runners, or stolons, and tends to be shallow-rooted and therefore needs adequate irrigation. The most common cultivar used in Hawai'i is Floratine, which is finer-textured than the common type. Other cultivars that have recently become more available locally include some of the newer semi-dwarf varieties, which are even more shade-tolerant, and insect-resistant varieties.

St. Augustine is established by vegetative propagation, because its seeds have poor germination and do not remain true to type. It is normally planted as sod, sprigs or plugs. Broadcasting stolons is not very effective. Well-rooted sprigs or 3- to 4-inch sod plugs should be planted about 12 inches apart followed by an application of the proper pre-emergence herbicide to suppress weeds during the grow-in period. A final top dressing of compost will provide beneficial micronutrients and help to keep the soil surface moist during establishment. New plantings should be lightly watered several times a day until the lawn has grown in.

The recommended mowing height for Floratine is 3 to 4 inches. The newer semi-dwarf varieties can be mowed at 1 1/2 to 2 inches. In either case, a good sturdy rotary mower should be used.

Mowing frequency will depend on the time of year and how fast the grass is growing. As with all grass, mow often enough so that no more than one-third of the leaf blade is removed at each mowing. Mowing too low will scalp the grass, leading to thinner coverage and more likely a hood of weeds getting a foothold.

Grass clippings should be left on the lawn if it is mowed often enough and at the proper height. Clippings contain very high levels of nutrients that will be recycled, cutting down on the necessity to fertilize. Contrary to popular opinion, grass clippings do not cause a more rapid buildup of thatch.

St. Augustine does not have a very high fertilizer demand. Depending on the desired quality of appearance and level of resulting maintenance that will be required, one to three applications of a good turf fertilizer annually should be enough. It is always best to use a fertilizer that has a high percentage of slow-release nitrogen; look on the back of the bag for the guaranteed analysis information. Use one pound of nitrogen per 1,000 square feet of lawn at each application, and always use a rotary-type spreader for even distribution — never throw out handfuls. More frequent fertilization will result in mowing more often, but will produce a higher-quality lawn. Care should be taken not to overfertilize: High levels of nitrogen along with over-watering leads to excessive thatch buildup.

St. Augustine produces a very dense lawn, which tends to choke out weeds if mowed at the proper height. If herbicides are needed, be sure to use the right ones. St. Augustine can be severely damaged by types that contain the active ingredient called MSMA or CMA. These are arsenic compounds used to control crabgrass and other grassy weeds. There are products that will control broadleaf weeds, but avoid those that contain 2-4 D. Look for products labeled for use on southern lawns. The sedge weeds such as nutgrass, kylinga and McCoy grass are best controlled by Image or Manage (now called Sedge Hammer). However, again be careful, both may temporarily discolor the lawn. Always read the entire label before applying any pesticide.

The main insect pest of St. Augustine is the chinch bug, a small fly that sucks the juices from the stems of the leaves and can quickly kill large sections of grass. The best control is an insecticide called Talstar or another called Merit. Brown patch and gray leaf spot can be occasional disease problems. Brown patch is more likely to occur in warm, humid weather and is encouraged by excessive nitrogen fertilization. Gray leaf spot is more prevalent during rainy periods and is encouraged by overwatering. Fungicides control both diseases.

Remember that the thick spongy thatch accumulation that is characteristic of St. Augustine is more rapid with overwatering and excessive nitrogen fertilization. This may require periodic de-thatching, a process referred to as verticutting. Be very careful to leave at least a half-inch of stolons at the soil surface.

Jay Deputy is an education specialist in landscape horticulture and turf at the University of Hawai'i-Manoa Department of Tropical Plant and Soil Sciences, and state administrator for the Certified Landscape Technician Program sponsored by the Landscape Industry Council of Hawaii. Got a lawncare or turf question? Reach him at deputy@hawaii.edu.