Several types of zoysia — creeping lawn grasses native to Asia and New Zealand — have become popular choices among Hawai'i residents who like their lawns well-manicured.

They're the most durable of the warm-season turf grasses — but once worn down they recover slowly. That makes them well suited for home lawns, public parks and golf course fairways — not football or soccer fields.

Zoysia grows best in full sun (but can handle partial shade). It grows more slowly than bermuda grass or seashore paspalum and may go almost dormant during January and February in Hawai'i. Reasonably salt-tolerant, zoysia can be grown along sandy seashores, where drainage is adequate. The dense grass spreads by underground rhizomes, resulting in a thick carpet of turf that tends to choke out other grasses and weeds. Some varieties are so aggressive that they may grow where you don't want them — under sidewalks, over curbs, and into flower beds.

There are a few seeded varieties of zoysia, but the most common types are sterile hybrids that must be propagated vegetatively, usually by plugs or sodding.

Meyer zoysia was introduced in Hawai'i in 1951. This was the first of several new vegetatively propagated selections of Zoysia japonica, commonly called Japanese lawn grass.

El Toro is a more recent Z. japonica selection from California. It has a medium to course texture with dark green leaves, resembling Meyer zoysia but with a courser leaf texture. What makes El Toro stand out is its rapid establishment rate — two to three times faster than other hybrid zoysia grasses. Highly drought-tolerant, El Toro is used for home lawns, baseball fields, parks and golf courses.

The two other naturally occurring species are Z. matrella (aka Manila grass), and Z. pacifica (aka temple or mascarene grass). Both must be propagated vegetatively, usually by plugs or sod.

Manila grass has a fine texture and deep green color. The blades are stiff and flat. The dense growth produces some mounding, and the turf is slow to establish. In Hawai'i, it is occasionally used for high-quality lawns and other fine turf areas.

Used as a ground cover in Asian gardens, finely textured temple grass has poky, stiff blades. The medium green, hair-like turf is extremely dense and low growing and seldom needs mowing. It produces pronounced tufts with a heavy thatch and is slow to establish. Less tolerant to wear than other zoysia grasses, it's not recommended for regular lawns.

Several other choices of zoysia are available in Hawai'i. Emerald zoysia is a hybrid of Z. japonica and Z. pacifica. Dark green and finely textured, it looks similar to Manila grass but is faster spreading and has a wider range of adaptation. It is used for high-quality lawns but builds thatch rapidly if not mowed at low heights. Z-3 is a hybrid of Z. japonica and Z. matrella that was selected at Quality Turf in Waimanalo. It has short, soft leaves with a medium-fine texture and medium green color. It grows more slowly than El Toro and builds some thatch when mowed above one inch.

More than any other factor, mowing — height, frequency, equipment — affects zoysia grasses' general appearance.

If cut infrequently at heights above two inches, most zoysia grasses will grow into a difficult-to-mow puffy, tufted, dense mat with a deep thatch. The lawnmower will severely scalp and tear the tufted turf, and in turn the turf can damage the lawnmower. For best appearance, zoysia lawns should be mowed every 7 to 10 days. The optimum mowing height for most zoysia lawns is three quarters of an inch.

A heavy reel-type mower must be used if mowing below one inch. A rotary mower will do an acceptable job at heights above one inch if the lawn is cut at least once a week. Frequent mower adjustment and blade sharpening are important for desirable turf grass quality.

One of the main problems with zoysia lawns, particularly emerald zoysia, is the fairly rapid build-up of thatch, which gives the lawn an uneven, clumpy look. If the grass has been consistently cut above the recommended height, much of this material will consist of long, brown stems and rhizomes. You can reduce thatch accumulation by mowing frequently at recommended heights and by avoiding over-watering and excessive nitrogen fertilizer applications.

Occasionally verticutting — mechanical thatch removal — is necessary to prevent deterioration of zoysia turf. The process results in major damage to the turf. A recovery period is necessary before the lawn returns to an acceptable appearance and should be done in spring or summer.

Zoysia requires frequent nitrogen fertilization only during its establishment. Once you have a thick, mature turf, one to three applications per year of a complete fertilizer (slow-release is best) at a rate of 1 pound nitrogen per 1,000 square feet is adequate. An occasional application of iron and micronutrients will result in an immediate "greening-up" without producing an increased growth rate.

Once established, zoysia, with its deep root system, requires little watering. Infrequent, heavy watering on an as-needed basis produces the best results. As with all turf grasses, the best time to water is just before or soon after sunrise.

Well-maintained zoysia turf will have few weed problems, but there may be occasions that call for weed-control measures. Zoysia is tolerant of many commercially available herbicides. Pre-emergence herbicides can be used regularly as a preventative measure to control weeds before they become a problem in mature lawns. It may be necessary to combine herbicides to control existing grassy and broadleaf weeds. For good postemergence control of crabgrass, as well as many broadleaf weeds, use Trimec Plus. Note: Trimec Plus may temporarily discolor El Toro, and the damage could be worse if the grass is not actively growing or under stress. Nut grass, McCoy grass and kyllinga are best controlled by applications of Image or Manage.

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 lawn care or turf question? Write to deputy@hawaii.edu.