By Ron Honig
May 14, 2025
Fertilizing Warm-Season Lawns
Turfgrasses should be fertilized when they are actively growing. For warm-season grasses that time is near. Late-spring/early-summer fertilizer applications are ideal for bermudagrass, buffalograss and zoysia grass.
Fertilizing too early in the spring encourages cool-season weeds to grow before the warm-season grasses are ready to compete. Fertilizing too late in the season (late summer) can increase their susceptibility to winter damage. Avoid fertilizing with nitrogen after August 15.
Late-May to early-June is the recommended time to fertilize warm-season lawn grasses such as bermudagrass, buffalograss, and zoysia grass. These species all thrive in warmer summer weather, so this is the time they respond best to fertilization.
The most important nutrient is nitrogen (N), and these three species need it in varying amounts.
Bermudagrass requires the most nitrogen. High-quality bermuda stands need about 4 lbs. of actual nitrogen per 1,000 sq. ft. during the season (low maintenance areas can get by on 2 lbs.). Apply this nitrogen as four separate applications, about 4 weeks apart, of 1 lb. N per 1,000 sq. ft. starting in early to mid-May.
The nitrogen can come from either a quick- or slow-release nitrogen source. So, any lawn fertilizer will work. Plan the last application for no later than August 15. This helps ensure the bermudagrass is not overstimulated, making it susceptible to winter-kill.
Zoysia grass grows more slowly than bermudagrass and is prone to develop thatch. Consequently, it does not need as much nitrogen. In fact, too much is worse than too little. One and one-half to 2 pounds N per 1,000 sq. ft. during the season is sufficient. Split the total in half and apply once in early June and again around mid-July. Slow-release nitrogen is preferable but quick-release is acceptable. Slow-release nitrogen is sometimes listed as “slowly available” or “water insoluble.”
Buffalograss requires the least nitrogen of all lawn species commonly grown in Kansas. It will survive and persist with no supplemental nitrogen, but giving it one pound of nitrogen per 1,000 sq. ft. will improve color and density. This application should be made in early June. For a little darker color, fertilize it as described for zoysia grass in the previous paragraph, but do not apply more than a total of 2 lb. N per 1,000 sq. ft. in one season. As with zoysia, slow-release nitrogen is preferable, but fast-release is also OK.
As for all turfgrasses, phosphorus and potassium are best applied according to soil test results because many soils already have adequate amounts of these nutrients for turfgrass growth. If you need to apply phosphorus or potassium, it is ideal to core aerate beforehand to create a path for the nutrients to reach deeper into the soil and closer to the majority of the roots. Phosphorus and potassium move very slowly through soil when applied to the surface.
