Establishment of Zoysiagrass Lawns

Zoysiagrass was introduced into the United States from Korea about 1900. A Zoysia japonica seedling with improved winter hardiness was selected from early plant collections and was released in 1951 under the name 'Meyer'. This variety has better low-temperature tolerance than most other zoysiagrass varieties and is still the best choice for the Midwest transition zone. Zoysiagrass is adapted to the southern two-thirds of Missouri, where it is used primarily for home lawns or golf courses where a dense, low-cut turf is desired.

Zoysiagrass is a warm-season grass that spreads by both rhizomes and stolons. Stems and leaves are tough and stiff. It requires only occasional irrigation and may give excellent-quality turf from mid-May through mid-September. Although zoysiagrass is a good choice for hot weather, it goes dormant as soon as fall frosts arrive and stays brown until weather warms in spring.

Zoysiagrass grows best in full sun. It will tolerate moderate shade, but the turf will be thinner and less competitive in shady areas. Zoysiagrass requires less supplemental irrigation and fertilization than most other turfgrasses. It grows best when maintained with low to moderate nitrogen fertilization. Established zoysiagrass competes well with weeds and other turfgrasses.

Establishment

Zoysiagrass lawns generally are established vegetatively with plugs (small cores of sod), sprigs (stolon or rhizome sections), sod or strips of sod. Zoysiagrass can also be established by seed. However, the varieties that are currently available often display variable leaf width, color and require further evaluation in the Midwest for winter hardiness. The best time to vegetatively establish a zoysiagrass lawn is during late spring to early summer. Late-summer (mid-August) plantings may not allow sufficient time for complete establishment making turf more susceptible to winter injury. Plugs and sprigs should be planted between late April and June. Sod can be laid as late as September as long as temperatures are warm enough for the sod to root into the soil.

Soil preparation

Proper soil preparation will lead to successful establishment and easier care of your lawn during succeeding growing seasons. Twelve steps for zoysiagrass establishment are listed below. These steps may not all be required to successfully establish your lawn. For example, soil need not be completely tilled where grading and soil amendments are not required and when soils are not excessively compacted.

1. Obtain a soil test and get fertilizer/limestone recommendations. Contact your local University Extension Center or see MU publication G6954, Soil Testing for Lawns.
2. Rough grade.
3. Apply lime, if needed.
4. Apply fertilizer as recommended by soil test.
5. Apply soil organic amendments if needed (such as peat moss or compost).
6. Till in above materials four to six inches deep.
7. Finish grade.
8. Apply starter fertilizer and work into top inch of soil.
9. Install sod, plugs or sprigs.
10. Water.
11. Mow.
12. Control weeds.

Sodding

While sodding is the most expensive method of zoysiagrass establishment, it does result in an "instant" turf. Although several weeks are required before a newly sodded turf can withstand traffic or play, sodding does provide an established turf cover. For this reason, it is often the preferred method of planting on erosion-prone sites.

Sod beds should be moist, but not wet, at the time of sodding. If soil is excessively dry, especially under high temperatures, rooting may be poor regardless of subsequent irrigation practices. Sod should be laid so that the ends of adjacent strips are staggered. Individual strips should be fitted firmly against adjacent strips and lightly tamped or rolled to provide uniform contact with the soil. When laid on sloping terrain, sod strips should be secured in place with stakes until rooting is sufficient to stabilize the sod.

Strip sodding. Strip sodding is a variation of complete sodding in which sod strips six to 12 inches wide are laid one to two feet apart and allowed to spread together. Strip sodding is less expensive than sodding, but the turf must be managed properly to achieve full coverage in a reasonable amount of time.

Plugging

Plugs are small pieces of sod, two or more inches wide with two to three inches of soil and roots. See Table 2 for information concerning proper plug placement.

A specially designed tool called a plugger or a long-handled bulb planter should be used to remove cores of soil the same size as the zoysiagrass sod plugs. This will make planting easier and ensure better soil contact with the plug. A starter fertilizer, such as eight pounds of 12-12-12 per 1,000 square feet, may be raked into the upper inch of bare soil before planting. The plugs should be kept moist before they are dropped into the holes. They are inserted into the soil, usually at six to 12-inch spacing, so that the tops of the plugs are flush with the soil surface. Closer spacing will give more rapid coverage. Plugs may be pressed firmly into the holes with the foot or lightly tamped or rolled after planting to ensure good soil contact. With no competition from other grasses, expect two growing seasons for complete coverage.

It is essential to keep plugs moist for the first two or three weeks after planting to prevent the roots from drying out.

Sprigging

The term "sprig" refers to a portion of the zoysiagrass plant that includes a short piece of the stolon or rhizome, roots and leaves, but not soil. Sprigging is less expensive than plugging and may give a faster rate of cover. However, sprigs require more initial and post-planting care than do plugs and are less likely to survive under adverse conditions.

The individual sprigs may be purchased from nurseries or separated from pieces of sod. Approximately two to three square yards of mature zoysiagrass sod will be needed to sprig 1,000 square feet of lawn surface. Late spring is the best time for planting sprigs. A starter fertilizer may be applied before sprigging.

Plant the sprigs in rows about six inches apart. Narrow furrows, two or three inches deep, can be made with a sharp spade or hoe. Do not let the sprigs dry out during planting. When planted in the furrow, one end of the sprig should be at least two inches below the surface of the ground, but part of each sprig must be above the ground. The furrow may be closed with a light roller or by walking on it to ensure good soil contact.

An alternative to planting sprigs in rows is to simply broadcast the sprigs onto a prepared bed. Water frequently (as many as three or four times a day) to prevent sprigs from drying out. A straw mulch (one bale/1,000 sq ft) will also help prevent drying.

Converting an existing lawn to zoysiagrass

Plugging and strip sodding can be used not only in planting zoysiagrass in bare soil, but in introducing it into an existing turf. For example, a Kentucky bluegrass lawn can be converted to zoysiagrass by planting plugs into the bluegrass turf. The conversion process is usually slow, but it can be accelerated by adjusting cultural practices to favor the zoysiagrass. Keep the lawn mowed short (one inch) to help the zoysiagrass spread. Fertilize on a schedule (May-August) to favor the zoysiagrass. Apply light applications of nitrogen fertilizer (about one pound of nitrogen per 1,000 square feet) every four weeks during the active growing season. It will take two to five years for the zoysiagrass to take over under normal circumstances. Excessive fertilization and irrigation will increase competition of existing grasses and will slow the spread of zoysiagrass.

Under most conditions, sprigging into an existing lawn is generally not as successful as plugging due to competition from the existing grass. Therefore, the planting area is prepared by killing the existing sod or weeds with a non-residual herbicide, such as glyphosate or glyfosinate-ammonium, and sprigged five to seven days later. This procedure will also speed establishment by plugging or strip sodding.

The articles in this special turfgrass issue were written by Brad Fresenburg, UMC Extension/Research Associate, Turfgrass Research Center, (573) 443-4893