There are two general kinds of turf grasses available. They are called Cool Season and Warm Season for obvious reasons. Only the Warm Season grasses can be used in Hawaii. Cool Season species like Kentucky bluegrass, fescue and rye will not survive the hot summers in Hawaii even though the seed is sold here as shade grass.
The Warm Season species are Bermudagrass, Paspalum (Seashore and some newer varieties), Zoysia (several varieties), Centipede and St Augustine.
Bermuda grass was once the most popular choice for home lawns in Hawaii. The traditional common Bermuda grass was widely used until the late 1960s when the first hybrid, Sunturf Bermuda, was introduced. Decades later other Bermuda hybrids became more popular.
Common Bermuda grass (Cynodon dactylon) can be grown from seed. There are many new improved seeded selections that are of much higher density and better color than the original type used several decades ago. However these seeded selections do not yet compete with the hybrids for top quality. The main advantage with these seeded types is the lower cost and ease of planting. All hybrid Bermuda varieties do not produce viable seed and must be planted by vegetative methods, usually by spreading stolons.
There is now a nice variety of Bermuda hybrids available. Until recently Tifsport and Tifway 419 were the best choices for sports fields and home lawns. Several new introductions , notably Celebration and Tif GRAND, have recently become available that have higher density and better color and are also reported to have better shade tolerance than the other Bermuda hybrids. Several dwarf varieties are also available, but they are best suited for use on high maintenance golf courses and high end homes and resorts.
All Bermuda grasses, both hybrids and common seeded varieties, require a higher fertilizer program than any of the other warm season grasses and show the least shade tolerance. Mowing is best with a reel mower at one half to three fourths inch mowing height for most hybrids and one to two inches for the common Bermudas.
There are several types of Zoysia (Zoysia japonica) available in Hawaii. El Toro, Z3 and emerald are the most common. El Toro has the widest blade, very similar to centipede grass. It grows much more rapidly than the other types and can be mowed at heights from three fourths to one inch with a reel mower or one to one and one half inches with a rotary mower. Z3 and emerald should be mowed lower, one half to three fourths inch. Emerald Zoysia blades have a very fine texture, often referred to as “pokey grass” and can develop a thick thatch and form mounds when cut above an inch. Emerald develops thick thatch much more rapidly than Z3 or El Toro. Z3 has smaller, thinner blades than El Toro.
All Zoysias have good shade tolerance and very high wear tolerance, but because of their slow growth, Z3 and emerald will recover very slowly when once worn down. All Zoysia varieties are normally planted from small squares of sod planted at about one foot intervals. The time for full establishment can vary from four to five months to longer than one year depending on the time of year, variety and planting distance.
Some newer varieties of Zoysia have recently been introduced. Zeon has a combination of a fine-textured look, very low irrigation requirements, substantially less fertilizer requirements, and very low thatch production. JaMur Zoysia is a medium textured grass, similar in look to El Toro grass, but it’s a lot easier to manage, needing less water and less fertilizer.
Geo Zoysia has a fine texture similar to Emerald, but with a much softer feel and lower thatch development and can be mowed below one half inch. Empire is a blue-green turf with a blade width slightly wider than El Toro and can be mowed from one half inch to two inches.
Seashore Paspalum (Paspalum vaginatum) has been widely used in Hawaii for its salt tolerance. Zoysia is also salt tolerant, but it handles salt in a completely different way. Where paspalum must be flushed with fresh water to move the salts through the soil column, Zoysia stores the salt in its leaf tissue. So, to remove salt from Zoysiagrass, all you have to do is mow it and remove the clippings.
Several varieties of paspalum are available. Seashore is the most common and the newest is Sea Isle 2000. Sea Isle 2000 is rapidly becoming the choice for golf courses, replacing the traditional Bermuda turf. The most outstanding characteristics of these paspalums are a fast growth rate and very high salt tolerance. On the down side, it builds thatch rapidly and is not very tolerant of many of the commonly used herbicides and is not very shade tolerant. Both varieties are best mowed under one inch with a reel mower. It is normally planted by spreading stolons or by plugs.
Saint Augustine grass (Stenotaphrum secundatum) is the coarsest of all of the warm season grasses used here. It must be mowed above 2 and one half inches and requires a heavy duty rotary mower. It can build a very thick thatch layer which will eventually lead to difficulty in mowing. It’s most endearing trait is very good shade tolerance along with fairly high salt tolerance. Planting is usually from rooted sprigs of sod. Several new dwarf type varieties such as Captiva St Augustine are now available which have finer, shorter blades, build less thatch, and tolerate lower mowing heights.
Centipede grass (Eremochloa ophiuroides) is the other choice available for Hawaii lawns. It is normally planted from seed and will establish in two to three months. Centipede has good shade tolerance but has very poor wear tolerance and requires more water than all other warm season grasses. It grows rather slowly and requires less maintenance than most of the other grasses.
For more information on any of the these grasses see the ads in this issue and for general landscape information visit the College of Tropical Agriculture and Human Resources website at www.ctahr.hawaii.edu. Click on publications on the home page.
Jay Deputy is the state administrator for the Certified Landscape Technician program and a Director Emeritus on the LICH Board of Directors.