The Shade Tolerance of Zoysia Grass

Sunlight Needs

• Lawn grasses all grow more densely in full to partial sun exposures. According to the University of Hawaii at Manoa Cooperative Extension Service, zoysia grass tolerates shade a bit better than other common warm-season grasses. Too much shade causes zoysia grass to grow even slower and not thicken quickly, leading to bare soil areas where opportunistic weed seeds sprout and challenge the grasses for resources.

Types of Zoysia Grass

• While there are three different species of zoysia grasses available for use as lawn grass, many of the modern zoysia grass varieties are improved mutations or hybrids. Horticulturists selected the best plants based on tolerances, leaf color, disease resistance and other preferable characteristics. Not all zoysia grasses tolerate shade equally. El Toro, Cavalier, Palisades, Diamond, Zeon and Zorro are a few cultivars with improved shade tolerances compared to older standby selections like Meyer and Emerald.

Shade Maintenance

• Typically zoysia grasses are maintained by mowing at rather short heights, around the 1- to 2-inch range. On highly manicured athletic fields, such as on golf course greens, zoysia grasses grown in full sun are mowed as low as 1/2 to 1 inch in height. According to Richard L. Duble of Texas A&M University, you shouldn't mow the grasses nearly as short if they are in shady environments. In order to make food in their leaves in the lower light levels, more leaf blade must remain to soak in the sunshine. Therefore, increase mowing heights on the shaded zoysia grass areas of the lawn, perhaps 1 inch taller than the usual mowing height across the sunny parts of the property. Duble notes that you still mow shaded grass with the same frequency as the sun-kissed lawn.

Correcting Problems

• If you insist on maintaining zoysia grass in a shadier area of the yard, several options are available. Besides mowing shaded grass slightly higher, you may investigate planting plugs of more shade-tolerant cultivars in the shaded area. A mix of grasses helps fill in bare soil areas so there is little obvious difference in the lawn's appearance from sunny to the marginal shady spots. Alternatively, if no zoysia grass performs well in the shady area, consider changing it from lawn to a planting bed of shrubs, perennials or annuals that do tolerate the light conditions.