Uneven lawn: how to straighten it

New build problem
In many cases, an unevenly straight lawn occurs in new builds because the soil preparation did not pay precise attention to an even surface. Subsequent soil settlements are another reason for uneven lawns.

Poor Water Drainage
When water cannot drain well into the deep soil, waterlogging occurs , causing the soil to contract after draining and causing subsidence . A drainage ensures improved water drainage, although this does not protect against enormous amounts of water, such as in the event of a flood.

Stepping on wet lawns
If you step on very wet lawns, the soil compresses – a hollow is formed, which often does not lift even after it has dried.

Tree Roots
In gardens, trees are often planted not far from the lawn. Their roots can spread unnoticed below the lawn surface and cause elevations.

Mole or vole
Moles and voles create underground tunnels and mounds of dirt in the lawn, which can cause bumps in the lawn.

preliminary work

There are a number of ways to straighten an uneven lawn. Basically, the method depends on certain factors as they result from the lawn examination.

lawn survey

No matter which method is used, in principle every project starts with the lawn examination. The following information should be collected during the lawn inspection:

• root cause
• Areas of uneven lawn areas (large areas of unevenness or only a few small areas affected?)
• Height/depth of bumps

Determination of height, depth, slope

Since it is difficult to see with the naked eye whether a hill or depression has only caused small areas of unevenness, it is always advisable to think of larger areas and to proceed in the same way as with sloping/rising lawns.

• Stick a wooden stick into the lawn at the lowest point (the wooden stick must be at least the length of the height difference)
• Stick a second wooden stick into the lawn at the highest point
• Connect both wooden sticks with a ribbon or twine
• The thread/tape must touch the ground on both wooden sticks
• Using a spirit level, slide the twine/tape to a straight horizontal line at the low point
• To measure the height difference, the centimeters are measured from the ground to the aligned thread/tape

planning

In the forefront of planning is the question of whether the lawn should be retained when straightening or whether a new seed should be sown. Depending on the surface of the bumps and the difference in height, reseeding is essential. In other cases, the old lawn can be preserved.

Simplest straightening variant: lawn roller

Even large areas of unevenness in the lawn can be straightened with a lawn roller without much circumstance and effort. Devices are available from specialist retailers that are filled with sand and/or water and can weigh up to more than 100 kilograms on the lawn. A lawn roller is suitable for elevations caused by moles, voles or the like. However, a lawn roller does not level depressions such as those caused by collapsed underground tunnel systems. Here an earth fill is required before rolling. The lawn roller is used as follows:

• Cut the lawn first
• If the lawn is very dry, a short watering after cutting the lawn creates better conditions for levelling
• Fill lawn roller with sand or water if not already done
• Ideally, always roll the entire lawn
• Start at the very back edge of the lawn and roll forward in even, adjacent strips
• Then roll the lawn again across the drawn strips (cross pattern)
• Do not roll young grass
  • may destroy the turf

Pile of soil on the lawn

In order to obtain an even lawn surface on inclines/slopes, the difference in height can be made simply by spreading layers of earth on the existing lawn. This method is not recommended for larger height differences, since progress is only possible in one-centimeter layers and a lot of time and patience is required.

Manual:

• Use a mixture of topsoil and sand for layering
• Spread the mixture a maximum of one centimeter high on the affected areas
• The grass grows through and takes root with the new layer of soil
• Time until rooting: two to six weeks, depending on weather conditions
• Then apply the next layer of soil, no more than one centimeter high
• Repeat until the difference in height is evened out
• Water well after each layer of soil (encourages rooting)
• Under no circumstances should you roll over the new layers of soil, otherwise the grass cannot be penetrated

leveling of the subsoil

If tree roots or poorly laid out ground are the cause of an uneven lawn, there is usually no other option than to solve the problem directly on/in the ground.

New ground on old lawn

This variant should only be used if the cause of the unevenness lies solely in a sloping subsoil, there is optimal water permeability and a slope is to be raised. New soil is simply laid on the existing lawn and the lawn seed is spread over it. How to proceed:

• Cut and scarify old lawn
• After scarifying , there are bumps such as those caused by collapsed tunnel systems
• Level them out to some extent with earth
• If possible, remove all weeds
• Use a piece of string to determine the area to be lifted (as described under “Preliminary work – determination of height, depth, gradient”)
• Fill in soil according to the height of the twine on old lawn
• Wait a few days, because filled soil can sag, especially after rain
• If necessary, correct the height of the earth again
• Level the ground with the lawn roller
• Distribute phosphorus fertilizer on the soil
• Then scatter lawn seed
• Cover the seeds by a maximum of half a centimeter with peat (encourages soil contact)
• Better results are seen when fertilizer is spread in one direction and lawn seed in the other direction
• Don’t let the soil dry out
• First lawn cut when the lawn is between 10 and 15 centimeters high
• Do not enter a newly created area before the first lawn cut
• Best time: between May and September

digging up

If the problem from an uneven turf is poor water permeability or uplift from a root, the problem needs to be addressed at the core. This means that the old lawn has to be removed and the subsoil dug up in such a way that drainage can be laid or the roots can be removed.

If necessary, the soil should be worked up so that it allows water to pass through better. If it is old, compacted soil, it should be replaced with new, fresh soil. Basically, this method is a complete replanting of the lawn when the water permeability is not optimal. Under certain circumstances, roots can also be removed with an area-limited excavation.

“Repair”

If you only have to straighten a few small areas, this can be done easily without significantly damaging the existing lawn. Thats how it works:

• Prick affected areas with a lawn edger in a cross shape
• Carefully “unfold” all four turf parts from the middle outwards
• Loosen the soil underneath
• Fill depressions with a mixture of earth and sand
• Remove elevations to level
• Firmly trodden down the tilled surface
• Fold back the turf parts and check the levelling
• If necessary, raise the turf again and correct the subsoil
• Do not let the areas dry out until the interfaces have grown well again

Conclusion
How an uneven lawn can be straightened primarily depends on how extensive the unevenness is. If the problem lies in poor water permeability of the soil, a complete renewal of the lawn is unavoidable. In all other cases, less effort is required.