Question: I've got several good sized holes in my yard. These aren't small holes like those created by chipmunks or crayfish or ground-dwelling bees. These are large holes created when trees have been removed or a sinkhole has developed. Some are the result of machinery brought into the yard to repair a broken irrigation system. Bottom line: in several locations there is a chunk of dead turf or a hole where grass used to be that I'd like to replace. Should I just have a load of sand or topsoil dumped in my yard to fill in the bare spots in and around holes or sunken areas?
Answer: The answer is .... It depends!
If the issue is to level a turf grass lawn because it's too bumpy to mow evenly or risk damaging the mower, then there are actions you can take short of hiring a company to do it for you, also an option.
If DIY (do it yourself) is your choice, and you're willing to pace the process instead of trying make one application do the job, this is a good time to start.
Most experts suggest the best time to fill uneven spots in your lawn is during vigorous growth - this time of year. And while coarse builders sand can be applied to fill very shallow spots of 1/2" or less, the majority of situations do much better with an application of a dry topsoil/sand mix. Some people add compost to the mix, which enriches the soil and gives that organic matter boost to root growth. The key is to add no more than a half inch to an inch at a time so roots can regenerate new growth that pushes up through the mix. After adding the leveling mixture, water the area to help settle it, and if fertilizer is applied, use a light hand. If the area is still too low, let grass grow about 4 - 6 weeks, when another 1/2" of the mix can be added.
When low areas are more than a few inches deep, using an edger or sharp shovel remove pieces of grass or groundcover, along with attached soil, from the bottom of low area and set them aside. Then fill the depression with topsoil to bring it slightly higher than the surrounding soil, replace sections of grass or groundcover, and water it in. Watering will help settle material added to the depression and reestablish roots of vegetation taken out. If there wasn't anything growing in the low spot or hole, simply fill the spot using same process as above, then reseed, re-sod, vegetate the spot, or mulch it heavily to prevent weeds from moving in until you've decided what to do.
If the area is low AND compacted, perhaps caused by heavy equipment, try using a digging fork under roots of grass or groundcover. Lift the roots up a couple of inches above surrounding grass or vegetation and let it settle back down - that may be enough to correct it. If not, use the same process outlined above to lift out any surviving vegetation, add topsoil or a topsoil and sand mix, then resettle vegetation. The objective is to open pore space in the soil so roots can re-establish.
Bottom line, dumping a load of sand and shoveling it into holes isn't the best practice. Be patient, even if it takes a couple of seasons to even out a really rough yard, fill in holes that used to be trees, or other gaps in the ground.
Garden Talk is written by Sallie Lee of the Alabama Cooperative Extension System (ACES). She is housed at the C. Beaty Hanna Horticultural and Environmental Center, which is based at the Birmingham Botanical Gardens. This column includes research based information from land-grant universities around the country, including Alabama A&M and Auburn Universities. Email questions to Sallie at firstname.lastname@example.org or call 205-879-6964 x11. Like us on Facebook. Follow us on Twitter. The Alabama Cooperative Extension System (Alabama A&M University and Auburn University), is an equal opportunity educator and employer. Everyone is welcome!