My lawn is looking off-color and tired. Is now a good time to fertilize and get it green again? Would this be a good time to plant some seed in thin spots?
Fall is a very important time for lawns. The shortening days and cooler nights stimulate grass growth. The growth of grass roots and rhizomes (underground stems) in particular is stimulated. Additional side shoots develop, making the lawn thicker. Fertilizer added during the next month or two just stimulates this process. It will also turn the grass a darker green color, usually within two days.
If you have not watered your lawn this summer, wait until it rains to fertilize. There are many good brands of lawn fertilizer. Some are specially formulated for fall application. Some are labeled as “winterizers.” These winterizers usually contain more potash or potassium. I still feel that the ideal balance for all lawn fertilizers is a 3-0-1 to 3-0-2 ratio of nitrogen, phosphorus and potassium. This could be 15-0-10 or 21-0-10 or similar percentages. I like to have at least part of the nitrogen from slow-release sources, although this is less important for fall application.
Another benefit of fall fertilization is that some of the nitrogen is taken up and used in making amino acids that are stored in the roots and crowns. These are available for immediate growth early next spring before the soil is warm enough for roots to take up fertilizer.
Fall is also the natural time for grass seed to germinate and grow. It is the best time to seed a new lawn or reseed existing thin areas. If you decide to plant seed, be sure to scratch or loosen the soil surface so seed can come in direct contact with the soil. Use a rake, tine cultivator or spading fork. Fertilize at the same time you plant the seed. Rake the seed into the soil leaving some showing on top. The most important step is to keep the soil surface constantly wet for at least three weeks. A thin layer of bark dust, fine compost or peat moss will reduce the drying rate. Light watering three times per day is needed unless rain occurs.