Home & Garden

September 13, 2013

Now’s the time to put in a new cool-season lawn

People who put redoing the lawn on the back burner because of the drought may be ready to get the job done this fall, extension agent Rebecca McMahon said. After this summer’s rains, there is subsoil moisture to help it grow, she said.

People who put redoing the lawn on the back burner because of the drought may be ready to get the job done this fall, extension agent Rebecca McMahon said. After this summer’s rains, there is subsoil moisture to help it grow, she said.

The window for overseeding is September through Oct. 15, though with the relatively cool summer, one has the feeling that fall could come on the earlier side, so “I’m not sure this is the year I’d advocate dawdling” in getting a new cool-season lawn in, McMahon said. If you want to plant a warm-season lawn, you’ll have to wait until May or June.

Start by assessing your lawn: If more than half of it is brown or in weeds, plan on putting in a whole new lawn. If less than half the lawn needs help, you can overseed the areas that need it, or patch them with sod.

Overseeding and seeding fescue in the fall should be done by Oct. 15, the earlier the better. Sod can be put down anytime the ground is not frozen. The ground also needs to be prepared properly before placing sod so that the grass will root successfully. Keep it moist until it roots down – you won’t be able to lift it with a light tug – and then start watering less often and more deeply to encourage the roots to go deep.

Of course, you can also hire a lawn company do the lawn installation for you. If you plan to do it yourself, read on.

How to overseed

Ward Upham of K-State gives these tips for overseeding:

• Start by mowing the grass short (1 to 1 1/2 inches) and removing the clippings. This will make it easier to achieve good seed-soil contact and increase the amount of light that will reach the young seedlings.

Good seed-soil contact is vital if the overseeding is to be successful.

• Check for thatch. Excess thatch can prevent seed from reaching the soil and germinating. Normally we want 1/4 inch of thatch or less when overseeding. If the thatch layer is 3/4 inch or more, it is usually easiest to use a sod cutter to remove it and start over with a new lawn. A power rake can be used to reduce a thatch layer that is less than 3/4 inch but more than 1/4 inch.
• Once thatch is under control, prepare the soil. This can be done in various ways. A verticut machine has solid vertical blades that can be set to cut furrows in the soil. It is best to go two different directions with the machine. A slit seeder is a verticut machine with a seed hopper added so the soil prep and seeding operation are combined.

A third option is to use a core aerator. A core aerator will punch holes in the soil and deposit the soil cores on the surface of the ground. Each hole produces an excellent environment for seed germination and growth. Make three to four passes with the core aerator to ensure enough holes for the seed. Using a core aerator has the additional benefit of reducing the amount of watering needed to get the seed germinated and growing. Aeration also increases the water infiltration rate, decreases compaction, and increases the amount of oxygen in the soil.

• Apply fertilizer at the rate suggested by a soil test, or a starter fertilizer should be used at the rate suggested on the bag.
• Seed the yard, using half the amount of seed used when working with bare ground. For tall fescue, apply 3 to 4 pounds per 1,000 square feet, broadcasting it with a spreader or by hand for small areas.
• Water everything in and then keep the seedbed constantly moist. Frequent, light waterings should give way to deeper and more infrequent irrigation as seedlings become established.
• Fertilize again four to six weeks after seeding using a high-nitrogen fertilizer.

Fall lawn seeding tips

Here are Upham’s tips for seeding:

The keys to successful lawn seeding are proper rates, even dispersal, good seed-to-soil contact, and proper watering. Evenness is best achieved by carefully calibrating the seeder or by adjusting the seeder to a low setting and making several passes to ensure even distribution. Seeding a little on the heavy side with close overlapping is better than missing areas altogether, especially for the bunch-type tall fescue, which does not spread. Multiple seeder passes in opposite directions should help avoid this problem.

A more serious error in seeding is using the improper rate. For tall fescue, aim for 6 to 8 pounds of seed per 1,000 square feet for new areas and about half as much for overseeding or seeding areas in the shade. Using too much seed results in a lawn more prone to disease and damage from stress. Using too little seed will result in clumpy turf that is not as visually pleasing. Determine the square footage of the yard first, and then calculate the amount of seed.

Establishing good seed-to-soil contact is essential for good germination rates. Slit seeders achieve good contact by dropping seed directly behind the blade that slices a furrow into the soil. Packing wheels then follow to close the furrow. The same result can be accomplished by using a verticut before broadcasting the seed, and then verticutting a second time.

Core aerators can also be used to seed grass. Go over an area at least three times in different directions, and then broadcast the seed. Germination will occur in the aeration holes. Because those holes stay moister than a traditional seedbed, this method requires less watering.

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