Over the past few years, El Toro zoysia and seashore paspalum have been among the most popular turfgrass choices for Hawai'i lawns.

Each species has its own special characteristics, and a comparison of the two may help in deciding which is best for your location and personal preferences.

Both El Toro and seashore paspalum have a very dense growth habit, spreading by stolons and underground rhizomes resulting in a thick carpet of turf that tends to choke out all other grasses and weeds. Both are so aggressive that they may grow under sidewalks, over curbs or small walls, and into flowerbeds or other unwanted areas.

Seashore paspalum is similar to Bermuda grass in appearance, but with a slightly wider blade and a shinier, darker green and waxier appearance of the blades. El Toro has an even wider blade and a medium-green color that more closely resembles centipede grass.

Zoysia and seashore grow best in full sun, but both tolerate partial shade reasonably well. Neither will do well in heavy shade. They are both very wear tolerant; however, El Toro takes much longer to recover once it has been worn down while seashore has a much faster growth rate.

Seashore paspalum can also tolerate very high salinity levels, higher than that at which most horticultural plants can survive. This allows it to be irrigated with high-salt, non-potable sources of water. Zoysia is moderately salt-tolerant and can be grown along sandy seashores, where drainage is adequate.

El Toro and seashore have similar water requirements. Both are reasonably drought-tolerant but require adequate irrigation for best appearance. Once established, they should receive deep irrigation once every three to four days, depending on soil type and season. Paspalum can tolerate waterlogged soil conditions much better than El Toro.

Each can be sodded, but it is more economical to use El Toro sod plugs for home lawns, planting 3- to 4-inch squares at 12-inch intervals and allowing them to grow together as the runners spread between plugs. This may take four to five months or more depending on the season.

Seashore paspalum can be established by spreading freshly harvested stolons over the entire planting area, followed by some type of mulching to keep them moist. Full establishment may take only four to six weeks depending on weather, since the growth rate of paspalum is so rapid. Seashore paspalum is usually less expensive to establish.

The general appearance of any turfgrass is probably influenced more by mowing than any other factor. Mowing height, frequency of mowing, the kind of mowing equipment and thatch removal are all important factors to consider.

The recommended mowing height for seashore is between 3/8 and 3/4 inch. El Toro requirements are from 1/2 to 1 1/2 inches. The optimum mowing height for each is 1/2 inch and 3/4 inch, respectively. All grass should be mowed often enough to remove no more than one-third of the blade length.

If cut infrequently at heights above the recommended height, both species will form a growth pattern that produces a puffy, tufted, dense mat with a deep thatch. This type of lawn is very difficult to mow, resulting in severe scalping and tearing of the tufted turf, and it can easily damage the lawnmower.

Therefore, for best appearance, El Toro lawns should be mowed every seven to 14 days and paspalum every five to 10 days at heights within the recommended range. A heavy reel-type mower must be used if mowing below 1 inch. A rotary mower will do an acceptable job at heights above 1 inch if the lawn is cut at least once a week.

One of the main problems with paspalum lawns is a rapid buildup of thatch. El Toro builds thatch more slowly. Heavy thatch gives the lawn an uneven, clumpy appearance. If the grass has been consistently cut above the recommended height, much of this material will consist of long, brown stems and rhizomes.

Thatch accumulation can be decreased by frequent mowing nearer the low range of the recommended heights, and by avoiding over-watering and excessive applications of nitrogen fertilizer. Paspalum may need annual verticutting to control thatch. This requires a period of recovery before the lawn returns to an acceptable appearance and should be done during the spring or summer months.

El Toro and paspalum do not require frequent N fertilization after the establishment period. When a thick, mature turf is established, one to three applications per year of a complete fertilizer (slow-release N is best) at a rate of 1 pound nitrogen per 1,000 square feet at each application is adequate for both.

The objective when fertilizing any lawn is to produce a slow-growing, healthy, attractive turf with as little mowing and maintenance as possible. An occasional application of iron and micronutrients will result in an immediate "greening-up" without producing an increased growth rate.

An established, well-maintained turf may have very few weed problems, but there may be occasions where weed control measures become necessary. El Toro is tolerant of many of the post-emergent herbicides that are commercially available, but seashore paspalum is very sensitive to many of them. Pre-emergence herbicides can be used on a regular basis as a preventative measure in all established turfgrasses.

For more details, visit www.ctahr.hawaii.edu and click on "free publications."

Jay Deputy is an education specialist in landscape horticulture and turf at the University of Hawai'i-Manoa Department of Tropical Plant & Soil Sciences, and is state administrator for the Certified Landscape Technician Program sponsored by the Landscape Industry Council of Hawaii. Got a lawn-care question? Write to deputy@hawaii.edu or call 956-2150 during working hours.