Renovating a Thin Lawn

Hot weather, insects, and diseases can cause lawns to decline and become thin. Thin turf areas can be renovated by following the steps outlined below.

  1. Determine and correct the problem(s) causing the lawn decline. Possible causes include hot weather, insects, diseases, unsuitable turfgrass species, and improper care. If the problem(s) is not corrected, the lawn will likely decline again.
  2. Select the best grass for the site. For example, seed mixes containing fine-leaved fescues are the best choice for shaded or partially shaded sites.
  3. Mow the lawn as short as possible.
  4. If renovating small areas, prepare the area by raking the thin spots. Large areas can be prepared by using a core aerifier or power rake. Go over the lawn 3 or 4 times with the core aerifier. Rake and remove all debris after power raking the turf area. For best results, aerification and power raking should be done when the soil is moist, not wet or dry.
  5. Small areas can be seeded by hand. Use a drop-type seeder when overseeding large areas. After seeding, work the seed into the soil by lightly dragging or raking the areas. Large areas can also be overseeded by using a slit seeder. A slit seeder makes a small groove in the soil and deposits the grass seed into the slit. (A slit seeder effectively combines steps 4 and 5 in the above procedure.) Core aerifiers, power rakes, and slit seeders can be rented at some garden centers and rental agencies.
  6. Apply a starter lawn fertilizer containing the preemergence herbicide Tupersan (siduron). Crabgrass is often a problem when overseeding in the spring. Tupersan is the only preemergence that will control crabgrass without affecting the germination of the turfgrass seed.
  7. Keep the soil moist with frequent light applications of water.

Late summer (mid-August through September) is the best time to overseed a thin lawn. Spring (mid-April through early May) is the second best time.

This article originally appeared in the April 12, 1996 issue, p. 53.


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