How to Properly Overseed Your Lawn

Jack Phillips
Adams County Master Gardener

With the coming of fall, property owners need to prepare their laws for the coming winter and for the spring and summer to come. The past summer has been very hard on the fescues which make up a large part of the standard lawn grasses which we use here in south-central Pennsylvania.

Your lawn is probably already showing the browned out areas and bare spots which result from a summer of extreme heat, hard wear and occasional periods of drought. Fall is the perfect time to do over seeding. Proper overseeding should include dethatching and perhaps aerating, if that procedure has not been recently cared for.

Eight Steps for Proper Overseeding

  1. Remove all debris which has accumulated on the lawn this season. This should include as many of the weeds in the lawn as can be easily removed by hand-pulling or by using a garden weeding tool. Removal of the debris is best done with a regular fixed-toothed steel garden rake.

  2. Mow the lawn to a height of 1 to 2 inches. Most lawn mowers are adjustable and with the cooler days and nights of fall, it will not injure the grasses to mow below the normally preferred height of 3 to 3 inches.

  3. De-thatch the lawn. You can hire a lawn service to do this or you can rent a de-thatching machine if your lawn is particularly thick with thatch of, say, 1 or 2 inches in depth. For the lawn with a normal amount of thatch, you need do nothing more than use a thatch rake , pulling it through the lawn much like a garden rake. Thatch rakes can be purchased or rented from most of the lawn and garden supply centers.

  4. Top dress the entire lawn area. For smaller lawns you can purchase bags of top-dress material from any garden supply center. For larger lawns you may wish to have a nursery deliver the necessary volume of applicable soil additive. It should be spread evenly over the lawn with a standard garden rake, generally to a depth not to exceed 1/2 to inches.

  5. Overseed the lawn. The main point here is don't skimp on price for the seed you purchase. If you choose a cheaper type of lawn seed mixture, neither you or your lawn will benefit by this overseed procedure. As to the type of seed to use, most south central Pennsylvania lawns that get a great deal of sun daily will benefit best by using a mixture of Kentucky Blue Grass and perennial rye. The low-maintenance tall fescue should be considered for the hard use areas such as children's playgrounds. On the other hand, shadier areas do better with the fine fescues.

  6. Read the labels. It is important to carefully read the labels on the seed bags to make sure you know exactly what you are buying. It is not a good practice to try to hand spread the seed except when you are repairing small bare patches. For an entire lawn, one of the hand held spreaders is probably the least expensive and most efficient tool to use.

  7. Rake the seed and top dress material lightly. This is done to move the seed more securely into the top dressing. This raking is best done with a flexible pronged leaf rake. You want to avoid burying the seed too deeply into the top dressing because grass seed will not germinate unless it is close to the top of the soil.

  8. Fertilize the entire lawn, but only if you have not already applied a lawn fertilizer earlier this fall. Quality fertilizers are designated as 'Starter' fertilizers. To develop good lawns, the fertilizer you use should contain a strong content of phosphorus and potassium. These two ingredients are what contribute most to strong root growth. The label for a typical Starter may read 26-8-10, for example. The first number refers to the nitrogen content. A word of caution: It is always advisable for you to obtain a soil test of your lawn so you know exactly which of the three ingredients, if any, are lacking. Water the lawn lightly for about 10-12 days. This is key to the entire procedure we call overseeding.

The grass seed you plant must be kept moist in order for it to germinate properly. Kentucky Blue Grass takes anywhere from 10 to 14 days to germinate, while perennial rye can germinate in as short a time as 5 to 7 days. Tall and fine fescues lie somewhere in between.

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