Zoysiagrass

Zoysiagrass is a good hot-weather grass on poor soil. It is neither all good nor all bad – it is desirable in some areas (e.g., Southern states) and the wrong grass to use on others (Northeast). In part, the decision to use or not to use zoysiagrass involves personal taste about its brown winter color. Before purchasing or planting zoysiagrass consider the following advantages and disadvantages.

Zoysiagrass should be used primarily in situations where a summer lawn is of primary importance. Zoysiagrass grows best and is most useful for areas which have sandy or gravelly soils. It is sometimes put to good use on sunny, south, or southwest slopes and on poor or sandy soils. It is occasionally used on curb strips between sidewalks and roads.

Advantages

• Grows especially well during the hot summer months.

• Produces a thick, dense, cushiony turf when established.

• Thick growth prevents and controls crabgrass and summer weeds.

• Has good green color during hot summer months when cool-season grasses may become unattractive.

• Withstands close mowing.

• Grows in most types of soil with proper management.

• Withstands wear and tear during the summer.

• Can survive severe heat stress.

• Tolerates low fertility once well established.

• Requires less water than most cool-season grasses.

Disadvantages

• Loses green color and becomes brown and straw colored about mid-October and remains this color until about mid-May.

• Propagation by vegetative establishment, with stolons or sod plugs, is necessary. This method tends to be expensive and laborious. Seed is generally unavailable and impractical. Seeded types are generally very coarse textured.

• Establishes slowly. Under ideal conditions, it may give cover in one season. Normally, two to three years are required.

• Winter annual weeds tend to be more of a problem in zoysiagrass than in cool-season grass.

• Spreads rapidly and difficult to eliminate once established; may be a nuisance around plant beds. It can also invade a neighbor's lawn or garden.

• Injury from persistent winter traffic can be severe while zoysiagrass is dormant.

• When brown and straw colored it is flammable and may be a fire hazard when allowed to grow tall near wooden buildings.

• Since it is tough and grows densely it requires more regular mowing in summer.

• While it tends to have less disease than most grasses, it is subject to some fungus diseases.

• It is not satisfactory for shade.

Establishment and Maintenance

A well-prepared weed-free plant bed is desirable when establishing zoysiagrass. Vegetative material may be planted as sprigs or plugs. (The term "sprig" applies to a vegetative portion of the grass plant and usually includes the leaves, a stolon (runner) and some roots.) Zoysiagrass is best planted during its early growing season from mid-May through June. Later plantings fail to cover the soil before frost and they will experience more winterkill.

Liming: Soil acidity for zoysiagrass should be maintained as for most regular grasses. The pH should be between 6.0 and 6.5. Have the soil pH tested and add limestone according to the pH results.

Fertilization: At the time of establishment of zoysiagrass on a rototilled or loosened plant bed, apply 10 pounds of 5-10-5 per 1,000 square feet. After establishment, late May fertilization is best; but it can be fertilized through early August. Established zoysiagrass requires less fertilizer than most grasses and it will endure long periods without fertilization. Do not use more than one pound of actual nitrogen per 1,000 square feet per application.

Mowing: Since zoysiagrass grows slowly, it does not require as frequent mowing in cooler growing weather as do some grasses. Mowing once a week during this season, however, will help to maintain smooth, well-groomed appearance. In hot weather it may need two or three mowings per week. The mowing height should be 1/2 to 1¼ inch. Zoysiagrass tends to form a dense mat when mowed low. Low mowing favors this grass and is especially beneficial when trying to get plugs started in established lawns. A close mowing in late April will remove brown leaf tips and encourage earlier greening.

Watering: Newly planted plugs and sprigs should be kept moist during the first two or three weeks. Established zoysiagrass turf does not require as much water as most cool-season lawn grasses. It will survive the early off-color wilt stage, but it should be watered when a darker gray-green or loss of green color develops in extended  drought periods. A slow application of one to two inches of water may be necessary on established turf during these times.

Chinch bugs, billbugs, and sod websorms: These insects may cause damage from June through September. Preventive or curative treatments when the insects are active  may be necessary to prevent serious damage.

Weed Control: After the lawn is well established, it usually has little need for weed control. Occasionally, a few broadleaf weeds and wild garlic (onion) do appear. These can be controlled with the common materials used for our cool-season grasses.

Thatch Control: Thatch is one of the most common problems. Remove thatch in mid-to-late spring, usually every year or two, depending on how much the grass is  fertilized.

Elimination

If you do not want to use chemicals, or if complete or fast elimination is not required, you can use the following procedures:

1. Fertilize in September and October only.

2. Raise the height of cut to 3 inches or higher. After several years, this type of management encourages the cool-season turfgrasses to overtake the zoysiagrass.

Faster elimination is possible. You would have to kill the entire zoysia lawn with a non-selective weed killer such as Round-Up (glyphosate), then renovate and reseed.

Adapted from Tom Kowalsick, Cornell Cooperative Extension, 2001