Hot weather, weeds, insects and disease often take their toll on lawns by the end of the summer.
Fall is the best time to renew bluegrass and fescue lawns. Overseeding is more than scattering seed and waiting for it to germinate. Seedbed preparation is as important for overseeding as it is for establishment of new turf. So before scattering expensive seed, take time to prepare the turf and correct any problems.
The first step in renovating a lawn is to determine and correct the conditions causing the problem. If this is not done, the problem likely will recur. Common causes of thin lawns are poor soil, more than 1/2 inch of thatch, insects, disease, the wrong grass and improper care.
The best weed control is planting at the right time and maintaining a thick stand of grass. Plant in September and then fertilize, water and mow to establish the grass before next spring when weeds invade the turf. Do not use crabgrass preventers before seeding or on young grass. Tupersan (siduron) is the exception. Do not use broadleaf weed killers (2, 4-D, MCPP, or dicamba) one month before seeding or on new grass until it has been mowed three times. Roundup can be used to kill all vegetation before seeding (five-day waiting period).
Mow the lawn short -- 1 1/2 inches -- before overseeding to keep grass and weeds from competing with new seedlings. Use a grass catcher on the mower or sweep up excess clippings. It is important to have less than 1/4 inch of thatch when overseeding. If thatch is 3/4 inch or more, it is easier to strip off the thatch with a sod cutter and reseed. Power rakes or core aerators are available from nurseries or rental agencies.
Selecting the exact grass for the right situation is necessary for a successful lawn. Overseeding is an opportunity to change the grass species or to add an improved selection. Check with the county Extension office for the latest recommendations on improved grasses based on university research. September is the best time to seed. This is when nature establishes cool-season grasses; therefore the best results with the least amount of work occur at that time. Do not delay seeding or the grass will not establish sufficiently before winter, and weeds like henbit and chickweed become a problem. March and April are second choices for seeding.
Use a rotary or drop-type grass seeder rather than applying by hand. If the soil has been furrowed with a power rake or prepared with other equipment, it will not be necessary to cover the seeding after sowing. Watering will settle it into the soil.
If only a few spots need to be reseeded, they can be prepared with a hand rake. Sow the seed uniformly by hand. A thin layer of fine soil can be spread over the seed or it can be worked in with the rake.
Water is vital. The seedbed must be continually moist during seed germination. If the germinating seeds or seedlings dry out even briefly, they will die.
Water with a gentle spray so as not to dislodge, wash, or move the seeds around while they are germinating. Daily water will be necessary at first, then gradually return to a normal watering schedule.
Apply a fertilizer indicated by a soil test or a complete slow release fertilizer during seeding to get the seedlings off to a rapid start. Avoid soluble fertilizers or excessive amounts because they will burn and kill the new seedlings. Fertilize about four to six weeks after seeding with nitrogen to build up the root system. November is the last month to fertilize.
Mow as soon as the new grass is 3 inches tall, with the mower set at 2 inches. Continue to mow at that height for the remainder of the season, including the last mowing. Water once or twice during dry winters when the soil is not frozen. Come spring, enjoy the fruits of your labor!
-- The Garden Calendar is sponsored by K-State Research and Extension-Douglas County office and written this week by Master Gardener Mickey Moss. For more information call the Master Gardener Hotline at 843-7058, between 1 p.m. and 4 p.m. Monday-Friday