How to Prepare the Soil for Planting Grass Seed

Most people don’t give enough thought to how they will prepare the soil when it’s time to plant a lawn.

You’ll be dealing with one of two options:

  • starting a brand new lawn
  • over-seeding an existing lawn

Starting a Brand New Lawn

If you’re starting a NEW lawn, or reseeding a very large area, till the soil to about 3 inches deep. Rake the area to get it fairly smoothed out. (If you’re dealing with extremely poor soil – for example a very sandy soil – it may be necessary to get a load of top soil brought in). After the surface prep has been done, apply whatever soil amendments were recommended. For example, if your soil test showed you need to add lime, add the recommended amount now.

Now is also a good time to apply starter fertilizer. Starter fertilizer should contain a high level of phosphorus (that’s the middle number on the fertilizer bag) to encourage seed germination. Just go ahead and spin this right on top of the ground according to the recommended rates using a broadcast spreader. Rake the lime and starter fertilizer into the soil.

Make sure the area is pretty smooth and then use a lawn roller to firm up the seedbed. This is important so that you can identify any soft spots that may be hiding out under the topsoil. When the soil is firm enough, you can walk across it without sinking in over a 1/4 of an inch and you should be able to bounce a basketball on it.

Over-seeding an Existing Lawn

If you’re over-seeding an EXISTING lawn, then aeration is a very important first step for successful lawn establishment. No need for a tiller here. Aeration breaks up compacted soil, allows your lawn to “breathe,” gives your roots a chance to go deeper into the soil profile, helps break up the thatch layer on the surface, and helps water infiltration. There really is no downside to aeration.

There are a couple of different types of aerators. First, a plug aerator will actually pull plugs out of your soil; it’s doesn’t just poke holes. You should be able to rent a good plug aerator at your local rental shop. Second, there is a coreless, vibrating aeration option as well. It’s demonstrated in the video below.

After you aerate your soil, just go ahead and spin your starter fertilizer right on top of the ground according to the recommended rates. Once you’ve done this, you’re ready to plant your grass seed.

Review – For starting a new lawn:

  • Till the soil.
  • Rake until smooth.
  • Amend with lime if needed.
  • Fertilize with starter fertilizer.
  • Rake lime and fertilizer in.
  • Roll soil until firm.
  • Bounce a basketball to be sure it’s firm enough to plant the seed.

Review – For seeding into an existing lawn:

  • Aerate the lawn.
  • Amend with lime if needed.
  • Fertilize with starter fertilizer.

Now you’re ready to plant some seed.

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