Fall is by far the best time to fertilize bluegrass lawns in the Washington area. Fertilization in the fall stimulates root growth and a good healthy root system can carry the grass through periods of severe stress. Spring fertilization, on the other hand, produces lush top growth requiring more frequent mowing.
The general recommendation for a bluegrass lawn is about 6 pounds of ntrogen per 1,000 square feet annually 4 pounds if most of the clipping are left on.) Ten pounds of 10-6-4, or 20 pounds of 5-10-5 fertilizer would provide 1 pound of nitrogen.
Four applications can be made, 1 or 1 1/2 pounds of nitrogen in mid-September, again in mid-October, again in late November, and again in early spring.
Regular or common bluegrass should not be fertilized in the spring. To do so increases its susceptibility to lead spot, a serious disease to which this variety is very prone, particularly in this area.
Windsor, Fylking and most of the other newer improved varieties of bluegrass do better with the higher rate of fertilization.
When you spread the fertilizer, do it evenly. If you go over the same area two or three times, you put on and it may cause burn. Be particularly careful when you make turns.
Fill the spreader of the lawn so that uf any fertilizer spills there won't be burned area.
Make a trial run with a new or unfamiliar spreader to familiarize yourself with its controls and to develop speed in shutting it off at the end of each trip across the lawn.
Do not apply fertilizer when the grass is wet. After applying the fertilizer, it is a good idea to use the hose to wash any fertilizer off the grass blades that may have stuck to them.
There can be a big difference in flow even with two spreaders of the same manufacture, or in your interpretation of exactly where to set the rate control.
Do not fertilize zoysia and Bermuda grasses later than late August. To Fertilize them in the spring after they have started to green up, and during the summer as need is indicated by color of the grass.