John, of Niu Valley, writes:

I have what looks like a zoysia-type grass that my father says is similar to temple grass. I want to replace it because although it is decent looking, the leaves are very sharp and I prefer a softer grass. We have tried to replace it twice, but it keeps coming back and eventually chokes out the new grass.

Also, the people my parents hired to maintain our lawn spread sand to try to level it out but have only succeeded in creating large sandy areas where the zoysia grows very sparsely. I believe the remedy is digging up and removing as much sand as possible, then mixing in some top soil to level it out. Since this will be almost half the yard, I might as well start all over and try to replace the grass one more time.

I am thinking that seashore paspalum would be a good choice and would like to know how to eliminate the zoysia from my lawn so that it does not come back. When would be a good time to start this project?

Dear John:

Your present grass is probably a zoysia hybrid called emerald, which has been used for home lawns in Hawai'i for many years. The grass blades can become stiff and pokey, particularly under dry conditions in full-sun areas. However, emerald has a moderately high tolerance to partial shade and if adequately watered and mowed at a height of about one inch, it will often become softer and easier on the bare feet.

If you absolutely want to replace it, choose a grass that is well adapted to your set of environmental conditions. If you have full sun most of the day, then any of the warm-season turf grasses will do well. Your choice of seashore paspalum does have a softer leaf texture and will tolerate some shade, but not as much as zoysia. Be aware, however, that paspalum has its own set of maintenance issues. (See my Dec. 22, 2006, and Aug. 29 columns.)

Several factors may enter into your decision on when to start the renovation. I would treat this as a "last time" effort and put plenty of work and time into the ground preparation. The existing zoysia will be very difficult to eliminate completely, but the sandy areas will require a complete soil reconditioning, which will also help get rid of the zoysia.

Give yourself at least several months for the entire preparation process. Start with two Round Up applications at two to three week intervals to take out most of the existing grass. When most of the present lawn is brown, start the soil conditioning. You do not have to remove all of the sand, but try to evenly redistribute it over the entire area. Use enough of a 50/50 topsoil/compost mix to cover the lawn to a depth of two inches — about one cubic yard of mix for 150 square feet. Finish by spreading five pounds of 10-30-10 fertilizer per 1,000 square feet.

Rototill the entire area to evenly incorporate the native soil and compost mix to a depth of 5 to 6 inches. Level the entire area to eliminate any of the pre-existing low spots and roll with a water-filled lawn roller to settle the loose soil.

The rototilling will bring up weed seeds and some surviving grass rhizomes which will begin to grow over the next few weeks. Treat any new growth with applications of Round Up until you are confident that most of the old lawn is dead.

This entire process may take as long as two months but will be well worth the effort. Start planting the new grass in mid-April. Depending on your choice of grass and method of planting, your new lawn should be grown in by midsummer.

Meanwhile, research the qualities of different species of turf grass, the available methods of planting them and their required maintenance.

Jay Deputy is an education specialist in landscape horticulture and turf at University of Hawai'i-Manoa Department of Tropical Plant & Soil Sciences, and 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.