Grass needs nitrogen fertilizer

Question: I planted sod about two months ago. It looks beautiful. How do I keep it this lush, green color and keep the turf through the cold months?

The key will be getting it fertilized right about Thanksgiving time with a high nitrogen fertilizer. Nitrogen is the element that lawns need to stay green when temperatures drop. This is true of the cool season grasses like the fescues, ryes and bluegrasses. The nitrogen helps keep it green to less than 20 degrees Fahrenheit if this is a fescue lawn.

If this is Bermudagrass, and you want it to stay green, you have to overseed it with perennial ryegrass now. Bermudagrass is a warm season grass from tropical and subtropical climates and will turn brown normally in the winter. The overseeded cool season grass like perennial rye will grow through the warm season lawn and keep the overseeded lawn green all winter.

The best fertilizers for lawns have numbers like 21-7-14, high in nitrogen, low in phosphorus and moderately high in potassium. Frequently, iron is a needed product for lawns growing in our desert soils. Ideally, half the nitrogen should be slow-release nitrogen.

If in doubt, stay with a named product like Scotts and just make sure the first number is high and the second one is about one-third or one-fourth of the first number. The last number can be high or low, but high is better in this case. Next March, aerate it and apply the same fertilizer.

Bob Morris is an associate professor with the University of Nevada Cooperative Extension.