Grass seed germinates best when it’s tamped into the surface of loosened soil and then kept consistently damp. While that’s doable with a stiff rake and a hose in small areas, what about large lawn areas in need of seeding or overseeding?

A little-known piece of power equipment can streamline the job without having to rake, till, or otherwise loosen the soil. It’s called a “slit seeder,” and it’s a machine that cuts shallow slits into the soil, then deposits seed into them in a single pass. These machines are often available for rent at the same equipment dealers that rent rototillers, core-aerators, log-splitters, and other yard equipment.

Find Toro slit-seeder and other lawn tools near you 

How does a slit seeder work?

Slit seeders, also known as "slice seeders," have vertical blades or discs that cut narrow furrows at adjustable depths in the soil before dropping grass seed into the furrows from hoppers at the back of the machine.

The majority of rental slit seeders are gas-powered walk-behind models that work similarly to a lawn mower, except that the blades rotate vertically rather than horizontally. For very large areas, slit-seeding machines are available that are designed to be pulled behind a tractor.

Depositing seeds directly into the soil offers four advantages:

  1. It’s less labor-intensive than having to loosen soil, then broadcast the seed and tamp it into place before watering.
  2. By inserting the seed, it’s in contact immediately with the surrounding soil.
  3. If there’s excess thatch when overseeding into an existing lawn, a slit seeder can both cut into the thatch (helping to decay it) and be set to deposit seed in the soil, not the thatch.
  4. Inserted seed is far less likely to be eaten by birds and other wildlife and less likely to run off if heavy rain occurs before the seed germinates.

Slit seeding is especially useful when trying to thicken a thin lawn or fill in bare spots after weedy patches have been killed. The machines cause minimal damage to existing grass while adding seed where it’s needed – all without having to dig, rake, or start over.

When and how to slit-seed a lawn

Slit seeders work best when lawn soil is damp after rain but not soggy or wet. It’s best to stay off wet lawns, especially with heavy power equipment, so the soil isn’t compacted.

The two best times to seed or overseed lawns are early fall and early spring – when temperatures are cool, the ground isn’t frozen, and soil moisture is better than in summer.

Before using the machine, make sure the cutting depth is set correctly. If seeds are planted too deeply, they will not germinate well, if at all. The top quarter-inch of soil is the sweet spot for grass seed germination.

You’ll also need grass seed to fill the hopper. The amount will vary depending on the area you’re seeding, the type of grass seed, and whether you’re starting from scratch on bare soil or overseeding an existing lawn.

See GreenView’s selection of grass seeds

Multiply the length and width of the lawn area to determine how many square feet you need to seed. Then check grass-seed bags for information on seeding rates.

If you’re using GreenView’s Fairway Formula Sun and Shade Grass Seed Mixture, for example, you’ll need four pounds of seed for every 1,000 square feet of new lawn or two pounds of seed for every 1,000 square feet in an overseeding job. 

For GreenView Fairway Formula Turf Type Tall Fescue Sun and Shade Blend, the recommendations are eight pounds of seed for every 1,000 square feet of new lawn or four pounds of seed for every 1,000 square feet of lawn to be overseeded.

Split the application rate in half and do two passes rather than applying all of the seed in one pass for the best results. Go one way the first pass and then perpendicularly on the second pass.

After slit-seeding, no straw or other mulch is required. However, for best germination, keep the soil consistently damp after slit-seeding, just as you would with conventional seeding.

Read more on how to start grass from seed

Read the three “secrets” of getting grass to germinate


Photo courtesy of The Toro Company