A patch of dead grass, even a small one, in an otherwise nice lawn can be an eyesore and a source of aggravation unless you know how to fix it correctly and quickly. Turfgrass sod — strips of mature grass with the roots and all attached — can make patching a lawn a fast, one-time task.

Do-it-yourselfers and others can easily get a handle on what to look for when buying sod and how to correctly install it. Follow these steps for repairing a lawn with turfgrass sod.

Step 1 — Identify what caused the old grass to die and fix that problem. Common culprits: too much traffic on the area, root-eating insects, disease or a chemical that spilled on the area. Fix the source of the problem, or you'll be repeating this step over and over again.

Step 2 — Prepare the area for replanting. Outline the patch area with boards, string or chalk, surrounding the dead area with straight sides. The straight sides will make it easier to fit the new sod without a lot of trimming, gaps or holes.

Next, till, spade or otherwise loosen the soil under the dead patch and rake it smooth while you remove roots, clods, rocks and other debris. For the best results, the soil in your yard and the soil the sod was grown in should be very similar. Most sod farms in Hawai'i grow the grass in a thin layer of compost on a plastic liner. If your yard has poor soil (heavy clay, for example), it should be improved by tilling in several inches of compost during the soil preparation. Mix in a small amount of a fertilizer high in phosphorus — about half a pound of 10-30-10 per 100 square feet of planting area. This will help the development of a healthy root system. Matching the soils between farm and yard does not have to be exacting, but avoid extreme differences.

Step 3 — Buy the same species of grass that is already in your lawn. Different types of grass have different maintenance requirements, such as water needs, mowing heights and shade tolerances. If you have a Bermuda-grass lawn, El Toro zoysia sod is not a good match. Know what fresh, high-quality sod looks like. Uniformity is important. Every piece of sod should be the same width, length and thickness, with square edges on all sides. It should all have been mowed to the same height, and there should not be any noticeable weeds or dissimilar grasses. When you look at the soil side, the bottom should be moist with no signs of dried roots. Every piece of sod should be strong enough to be lifted from one end and not fall apart.

Step 4 — Measure the four sides of the tilled area and convert this to square feet. (3 feet wide by 4 feet long equals 12 square feet, for example). Purchase enough fresh sod from a turfgrass sod farm, home center or garden center to finish the repair. Garden centers usually sell sod in plastic flats that are 12 inches by 18 inches (1 1/2 square feet), sod farms cut large sections directly from the field that are typically 2 feet by 4 feet (8 square feet)

Step 5 — Within hours after buying the sod, begin installing it onto the tilled area by placing the first piece along the longest straight line. All subsequent pieces of sod should be aligned tightly against the first piece, without stretching or overlapping. If cutting is necessary, use a sharp utility knife or razor blade. Cut on the undersoil side of the sod using a board as a straight line guide.

Step 6 — Ensure the new sod has good contact with the soil underneath by either using a half-filled lawn roller, or by placing foot-square boards on the new sod and walking on the boards a few times. If necessary, fill in any gaps between pieces with top soil.

Step 7 — Water the new patch until the soil under the sod is wet but not saturated. Depending on how sunny the location is, the amount of wind or other drying conditions, you may have to water the patch more than once a day for the first week. If the soil beneath the sod is not wet, you need to apply more water. During the grow in, you can check to see how well the sod is rooting by lightly tugging on a corner of a sod piece.

Step 8 — Restrict traffic on the area for at least two weeks to give the grass a chance to grow roots and for the soil to settle.

Step 9 — Mow the area about two weeks after patching, or whenever the sod is tightly rooted. If possible, try to run your mower diagonally across the sod seams. This will reduce rutting and the chance of your mower lifting a corner of sod from the new patch.

Any finally, know what care is required for your lawn. Every type of turfgrass has unique requirements for watering, fertilization and mowing that should be understood and implemented to keep a lawn beautiful for years to come. Without proper maintenance, the benefits of all of the other efforts to create a beautiful lawn can be lost. By knowing what to do and when to do it, you don't have to become a slave to your lawn.

Jay Deputy is an education specialist in landscape horticulture and turf at University of Hawai'i-Manoa's 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.