Yard and Garden: Seeding Lawns

Choosing the right grass species is the first step in establishing or reestablishing a lawn. Horticulturalists with Iowa State University Extension and Outreach answer questions about establishing turfgrass. To have additional plant and garden questions answered, contact the ISU Hortline at 515-294-3108 or hortline@iastate.edu.

When is the best time to sow grass seed in Iowa?

Mid-August to mid-September is the best time to seed new lawns and overseed existing lawns in Iowa. Late summer seeding has several advantages over spring seeding. The seeds of cool-season grasses germinate quickly in the warm soil of late summer. The warm days and cool nights of early fall promote rapid turfgrass growth. The growing grass also has less competition from weeds as few weed seeds germinate in fall. Grass seed can also be sown in spring (April to mid-May) in Iowa. Spring seeding, however, is often less successful than late summer seeding. 

What should I look for when buying grass seed? 

When purchasing grass seed, choose a high quality seed mix that is best adapted to the site. In sunny areas, Kentucky bluegrass is the best choice. Select a seed mix that contains at least two or three bluegrass varieties. Use a mixture containing Kentucky bluegrass, perennial ryegrass and fine-leaf fescues in lawns that have areas of sun and shade. Kentucky bluegrass will dominate in the sunnier areas, perennial ryegrass germinates quickly and grows in both sun and shade, and the fine-leaf fescues will thrive in the shady portions of the lawn. The fine-leaf fescues (creeping red fescue, hard fescue, chewings fescue, etc.) are the best grasses for shady locations. Avoid low quality seed mixes that contain more than 20 percent perennial ryegrass and large amounts of weed seed or inert material. While a high quality seed mix will be more expensive, it will produce a better quality lawn.

This summer’s hot, dry weather destroyed a large area in my lawn. How do I reestablish grass in the dead area? 

Grass can be reestablished in the dead area by sowing grass seed in late summer (mid-August to mid-September). Good site preparation is necessary for successful establishment of turfgrass.

Small areas can be prepared by raking the dead spots (the objective of raking is to break the soil surface). Sow the seed by hand. Then, work the seed into the soil by lightly raking the areas a second time.

Large areas can be prepared by using a core aerator. Core aerators are machines with hollow metal tubes or tines. They remove plugs of soil when run over the lawn. To prepare the site, go over the lawn three or four times with the core aerator. When finished, there should be 20 to 40 holes per square foot. Apply the seed with a drop seeder. Afterward, drag the area with a piece of chain link fence or drag mat to break up the soil cores and mix the seed into the soil.

After the seed has been sown, keep the upper 1 inch of soil moist with frequent, light applications of water. It’s often necessary to water newly seeded areas once or twice a day. With adequate moisture and favorable soil temperatures, the seeds of most turfgrasses should germinate in two or three weeks.

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PHOTO: Kentucky Blue Grass – 613 KB

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