How to fill low spots over existing grass in my yard?

Question

I read this question and it made me think of what I need to do this weekend. But I have these questions:

• If I've got a few holes - maybe a place where a bush was dug out and the ground eventually settled and every time I mow over it I scalp the lawn - how do I go about spreading the fill over the lawn?

• Do I need to reseed the grass, or will the grass underneath poke through eventually?

• If it will just kill the grass beneath, should I work up the existing soil with a pitchfork or something?

• Could I rip the sod out, tuck some dirt underneath and return the sod to it's newly elevated location?

Answer 1

When filling in low spots on a lawn, fill to a depth of no more than 1inch (25mm) at a time and fill in no more than twice a year, once in early to mid Spring and once in early Autumn (Fall).

As long as you fill in no more than 1inch (25mm) at a time, the grass will happily work its way through and fully establish itself at the slightly new higher elevation.

If you have a few inches (75mm or more) to fill in, you can most definitely remove the sod, fill underneath, then lay back the sod:

• Carefully remove the sod.

  • Remove in sections, something like 12inch (300mm) x 12inch (300mm) x 4 to 6inch (100 to 150mm) deep.

• Add your fill material (see below for recommendation).

  • If adding more than 4inch (100mm) depth of material, add in 4inch (100mm) layers, each layer should be "lightly" tamped down (do not over compact).

• Carefully lay back your sod, the sod should sit approximately 1 inch (25mm) above your finished required level ie The relaid sod should be sitting high.

  • Lay a scaffold board (or similar) over the relaid sod, shuffle up and down the board a few times. This will ensure good contact is made between the fill material and the sod, and the sod will lower (settle) to it's new final required level.

• Sprinkle a thin layer (¼ to ½inch / 6.25 to 12.5mm) of compost over the area you've finished bringing up to grade.

• Water once a day for the next 7 days, so the area remains moist (but not saturated).

  • After that time, water your entire lawn as you would normally.

Fill material: Personally I would use a 50-50 mix of "high quality" screened (¼inch/6.25mm sieved) top soil & compost for filling in low spots in a lawn.

• "High quality" = Make your own from compost and soil (materials) you control, or buy from a local independently owned garden nursery, or if you're lucky enough to have access to a local (free) community composting facility that is known to output good quality material.

  • Basically you want to reduce the risk as much as possible of bringing in lots! of weed seeds into your environment.

Answer 2

I patched and filled several areas this fall, in New England, with great success. First, I removed all the debris; someone had turned wire fencing under the ground from a garden of the original owner, about 8 years ago, along with wooden posts. Every time I started to rake the existing soil smooth, my rake caught something else. I finally just dug it all up by hand, and then smoothed it out.

In area where there was existing grass that I was going to cover, I burned it with a propane blow torch; the kind that attaches to a grill tank. I then covered it with a mixture of top soil, peat moss, grass seed, and starter fertilizer; all together. I would mix the top soil and peat in a wheelbarrow, and then add the proper proportions of seed and fertilizer. I put down about an inch or two of that and raked it lightly to smooth it out. I did not tamp it down. I watered it every day to keep it moist, and with the sunny an cool weather we had in September, the grass all came up in a week; and I mowed it twice before it stopped growing for the season. This was not the first time I had used this approach, but it turned out better than ever before because of the cooperative weather. I actually did that previous garden area in early October, and the weather was a bit cooler. That area sprouted in about 10 days, but never got to reach full height; yet.

The backyard of this house we bought 2 years ago must have been filled when the house was built, as it has settled more since we moved in. I filled some of it to correct that, but some of those areas, 1 to 2 feet in diameter, continue to sink. So, I just sprinkle soil over them without completely covering the grass. and let the grass do whatever it need to to adjust.