What Is the Optimum Growing Temperature for Warm Weather Grass?

Ideal Temperature Range

• Warm-season grasses grow at temperatures between 70 and 120 degrees Fahrenheit, with the most vigorous growth occurring between 80 and 95 degrees F. The roots of most warm season grasses require a temperature between 64 and 100 degrees F. Grasses adapted to warm weather begin to grow in the spring and peak in the summer before going dormant with the onset of cold weather and the first frost. These temperature differences mean that grasses adapted to warm weather require different fertilization, watering and mowing techniques than their cool-season counterparts.

Warm Season Grass Varieties

• Most warm season grasses grow via runners and stolons. The most popular varieties include Bermuda grass, zoysia grass and St. Augustine. Bermuda grass is dense, green, hardy and tolerant of disease, drought and wear. It is also a quick maturing variety. It requires full sun and spreads aggressively. St. Augustine grass is a duller green and more tolerant of shade. It produces wider, flatter leaves with a prostrate growth habit. It spreads by stolon, rather than rhizome, and tends to thatch. Zoysia grass is relatively slow to grow and establish, spreading via rhizome and stolon, with stiff leaves and higher shade tolerance than other warm season varieties.

Advantages of Warm Season Grass

• Warm season grasses are an ideal choice for areas with high heat, long growing seasons and limited moisture. Warm season grasses will stay green and presentable in weather that would result in dormancy or death for cool-season varieties, and they are also more tolerant of soils with poor moisture retention, poor drainage, varying pH and low overall fertility. Most varieties turn brown and dormant in cold weather, however, making them ill-suited to areas with long winters or cold, wet climates.

Cultural Considerations

• Warm season grasses require specific turf-management strategies, especially in the areas of water and fertilization. They should be fertilized when leaves are fully green and the season of most vigorous growth has started, although this may vary according to specific varieties. Avoid fertilizing warm-season grasses in the summer, and give them an extra application in winter to encourage a longer period of growth before dormancy. Water warm season grasses more heavily in warm months, and sparingly in cool or winter conditions, the opposite of cool-season grass irrigation.