Bumpy lawn - Knowledgebase Question

Port Washington, WI (Zone 5A)
Question by myl0wridr
May 12, 2008
I have a rather bumpy lawn. What is the best way to get rid of this problem? From what I've heard the best thing to do is to regrade. Is rolling your lawn REALLY that harmful?

Answer from NGA
May 12, 2008


Bumpy, rough, uneven lawns are annoying, difficult to mow, and potentially dangerous. Several factors contribute to bumpy lawns.

Many older, established lawns become rough and uneven over time as the turfgrass gradually thins. Sparse, thin lawns have less foliar growth and cushioning effect than thick, dense turfgrass. Thin lawns may be caused by poor maintenance, shade, insects, diseases, and other factors. The reestablishment of a healthy, thick turf would help to alleviate this problem. Bluegrass is generally the best grass for sunny areas, while the fine leaf fescues tolerate considerable shade. Tall fescue is also shade tolerant.

Freezing and thawing of the soil during late winter and early spring also contributes to the roughness of lawns. The repeated freezing and thawing lifts up or "heaves" the soil, causing the soil surface to become rough or bumpy.

Small castings left on the soil surface by earthworms also contribute to the roughness of lawns. While earthworms are partially responsible for the roughness of lawns, their activity improves the growing environment of the turfgrass plants. Earthworms improve the turfgrass environment by helping to decompose thatch. Their holes improve air and water movement in the soil. Earthworms also improve soil structure. The presence of a large number of earthworms in the yard and garden indicates fertile soils. The destruction of earthworms is not desirable nor feasible. Earthworms are beneficial and most pesticides registered for lawns and gardens will not kill earthworms.

Good lawn care practices can help to alleviate the problems associated with rough, bumpy lawns. An application of fertilizer in the spring should thicken the turf and make the bumps less noticeable. Best results can be obtained in late summer (late August to mid-September). Begin by core aerifying the lawn. Then power rake the area. The power raking will break down some of the bumps in the lawn and also break up the soil cores deposited by the core aerifier. Rake off any loose debris (thatch) brought up by the power rake. Then sow appropriate grass seed for the site. Rake the area with a leaf rake to work the seed into the soil. Finally, keep the soil surface moist to encourage germination. The lawn should be thicker and the surface less rough upon completion of these steps.

Rough, bumpy lawns should not be rolled with a heavy roller. While rolling the lawn will remove some of the roughness, it also damages the turf by compacting the soil. Compacted soil conditions reduce turfgrass vigor and may eventually lead to a thinner lawn.

Rough, bumpy lawns are annoying. Breaking down some of the bumps by power raking and developing a thick, healthy turf should help alleviate this problem.

Name: J.R. Baca
Pueblo West Co. ( High Dessert (Zone 6a)
Answer from josebaca
September 4, 2017


Low and high spots in the lawn are indeed annoying, and downright dangerous on a sports field. Right now we are going through our ' monsoon ' season so we are topdressing our worst fields and within the next few weeks we'll be aerating (core) as well.
We are always asked what do do with the ejected plugs and our universal answer is "nothing". The rainfall or irrigation will 'melt' them , and , being wet it will automatically seek the lowest sections. Over a period of a few years and doing both of these things in the spring and fall, you won't have that problem again.
On a side note it is healthier for the grass to be mown in a different direction each week as in horizontal, vertical and both diagonal directions. Our fields, especially around the periphery are consistently rutted by the big mowers we use and having a north and south shop, you could actually see the difference in technique results where the southside consistently mows the same way every week.
Also, in my opinion, power raking does more harm than good especially if you have a naturally loose soil and in the best of days causes severe root damage
Hope this helps.

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