With the days getting shorter, I'm reminded that there are some important turfgrass management activities to be completed in late summer and early fall. Proper practices can help maintain a vigorous lawn or revive declining turf. These practices include mowing, fertilization, dethatching, aeration, weed control, and seeding.
Mowing produces a well groomed appearance. How ever, improper mowing causes lawn problems. The cool season grasses, includ ing the most popular Ken tucky bluegrass, perform best in the cool weather of spring and fall. Bluegrass lawns are typically mowed at a height of 3 to 3 ½ inches during the hot, stressful summer months. The mower blade can be lowered to 2 to 2 ½ inches as temps cool in late summer. Mow often enough so that no more than 1/3 of the total leaf sur face is removed. Continue mowing the lawn until it stops growing and becomes dormant in early to mid November.
Late summer/early fall is an excellent time to fertilize lawns. Use a complete fertil izer, one that contains nitro gen, phosphorus, and potas sium (N-P-K). Best results are typically achieved by fer tilizing once in the spring and twice in the fall. Fall applications can be made in September and early November. September fertil ization promotes a moderate rate of shoot growth and helps to thicken the turf. An application in early Novem ber, at about the time of the last mowing, pro motes root growth and early green up next spring. Apply one pound of actual nitrogen per 1,000 square feet in both Septem ber and early November.
Thatch is the layer of dead and living plant material that forms between the soil surface and green foliage. When thatch is present in amounts greater than 1/2 inch, dethatching may be beneficial. Vertical mowers and power rakes, available from many rental companies and garden centers, thin the grass and lift the thatch to the soil surface. The debris is then raked from the lawn and discarded. Thatch removal can be done in late August or September. Allow at least four weeks of good growing weather following dethatching to give the turf grass time to recover before it becomes dormant in the late fall. Apply fertilizer after dethatching to promote recovery of the turf.
Lawns subjected to heavy foot traffic may be thin due to compaction. Aerify com pacted soils in late August or September with a machine that has hollow metal tubes or tines that remove plugs of soil from the lawn. Avoid spike-type devices that simply punch holes in the turf. Break up the soil cores by raking or mowing after aerification. Then apply fer tilizer to promote recovery of the turf.
Perennial broadleaf weeds, such as dandelions and plan tain, can best be controlled with the application of broadleaf herbicides from mid-September through October. Effective broadleaf herbicides include 2,4-D, MCPP, MCPA, dicamba, and triclopyr. The most effective broadleaf herbicide products contain a mixture of 2 or 3 of these herbicides as no single compound will control all broadleaf weeds. Fall appli cations of herbicides are safer and more effective than those in the spring or summer. During the fall, perennial weeds translocate carbohydrates down to their roots. If a broadleaf herbi cide is applied at this time, it will also be translocated to the roots, resulting in the complete destruction of the weeds. With gardening activity winding down in the fall, the risk of herbicide drift injury to vegetable and flower gardens, fruits, and ornamentals is also reduced. Late summer or early fall is an excellent time to estab lish new lawns or overseed thin or severely damaged lawns. Seeding may begin in mid-August and should be completed by September 30.
Our Extension Office has some excellent publications on lawn mowing (Lawn Mowing RG 406, and Cool season lawns RG 405). Stop in and talk to one of our staff. We are located at 209 Centennial Drive, Suite A, Cherokee, IA our phone number is 712-225-6196.