If bare spots appear in your lawn or sports field, overseeding can be performed to help repair the turf. Small areas can be seeded by manually distributing grass seed, but larger areas are more easily seeded using a spreader.
For cool season grasses such as fescue or bluegrass, overseeding can be successful when done in the spring (mid-March) or fall (early September). A few drawbacks to spring overseeding are the competition the seed will face from weeds and the water requirements of the seedlings as they enter the summer months. Another consideration to spring overseeding is that pre-emergent grassy weed control will inhibit seed germination. Fall overseeding usually does not have the weed competition or drought stresses of spring overseeding. (Recent years have shown that droughts can happen in the fall, but fall normally brings precipitation.)
We usually recommend overseeding at a rate of 5 to 8 pounds of seed per 1,000 square feet of lawn for tall fescue, and 1 to 2.5 pounds per 1,000 square feet of lawn for bluegrass. Currently, we sell our fescue seed in 50 pound increments. We do not tend to keep HGT Kentucky bluegrass seed on our shelves, but it can be purchased from various retailers online. Make sure to look for the bold yellow HGT bag with Barenbrug listed on the packaging.
If you do not require 50 pounds of seed for your area, we always recommend purchasing a premium brand of seed from a local garden supplier. The certified seed blend that we use comes directly from the grower, so the turf blends at the garden supply may not be an exact match, but quality turf type tall fescue seed should blend well into the sodded area. For overseeding fescue sod, look for varieties described as “turf type” for tall fescues listed on the seed tag. Avoid Kentucky 31 ("K31") tall fescue and ryegrass seed varieties, as they will not blend with the turf type tall fescue sod in your lawn (K31 and ryegrass will not blend with the turf type tall fescue or bluegrass and will not be aesthetically pleasing) .
For optimal seed-soil contact and seed germination, we recommend mechanically disturbing the soil in the area to be overseeded. This can be accomplished in small areas manually by going over the soil with a hard-tine rake 3 or 4 times. A walk-behind spreader can then be used to distribute the grass seed. Slit-seeders work well for larger areas. The slit-seeder will disturb the soil and distribute the seed simultaneously. We suggest overseeding with the slit-seeder by making two passes. Spread one half of the seed with the machine going in one direction, then making the second pass with the remainder of the seed at a 90º angle to the first pass. Plan to water the overseeded area roughly ½ inch every third day, for 3 to 5 weeks for best results.