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How to Calculate Grass Seed for Overseeding

How to Calculate Grass Seed for Overseeding
Healthy, dense turf is prized for its contribution to the all round appearance of a yard or landscape and as a groundcover. Where a lawn is thin or completely brown in winter but is otherwise healthy with no main problems related to diseases, pests, weeds, compaction, drainage, a too-thick thatch layer or soil nutrition, overseeding provides a viable means to improve the appearance of your lawn. The amount of grass seed needed to attain a full, green lawn is dependent upon the species of grass selected for overseeding along with the size from the area that you will overseed.

  1. Measure the edges of the lawn area you plan to overseed in feet. If the lawn space has more than four approximate edges or has an irregular shape, subdivide the area into smaller sized squares or rectangles and measure adjacent edges on each rectangle. If you measure many of these rectangles, create a small diagram with dimensions to keep track on the measurements.
  2. Multiply the two adjacent sides of each rectangle and add the total of each rectangle, in square feet, to determine the total area of grass you will overseed. Round as much as an increment of ten or 100 to simplify the calculations. For example, a rectangle 10 feet wide by 5 feet long would be 50 square feet.
  3. Divide the total area of the lawn by 1,000, as seeding rates are typically advisable in pounds of seed per 1,000 square feet, to determine the number of 1,000-foot sections. If you have a small lawn, this number might be a decimal that is much less than 1.
  4. Choose the grass species of blend that you will overseed the lawn with. To overseed a thinning but otherwise healthy lawn, choose precisely the same species and cultivar or a grass with related characteristics to ensure uniform color. To bring winter color to your lawn, pick a cool-season grass such as ryegrass, bluegrass, bentgrass or fescue.
  5. Multiply the number of 1,000-foot sections in your lawn -- or the decimal you calculated to get a small lawn -- by the seeding rate for the turf species. For colonial and creeping bentgrasses, the seeding rate is usually 1/2 to 1 pound per 1,000 square feet. Plan on requiring about 3 pounds of bluegrass seed, ten pounds of ryegrass seed, 4 pounds of red fescue, 5 pounds of tough fescue or 8 to ten pounds of tall fescue seed for every single 1,000 square feet of turf.


Spring is the best time to overseed your lawn, even though many winter-hardy grasses will survive if seeded early adequate inside the fall.