How to Firm up Your Lawn (5 Causes and Fixes)

Not only is a soggy lawn uncomfortale, but it can put a stop to any plans you have for your yard. In order to firm up your lawn, you need to know what’s caused it to become soft in the first place.

The 5 causes of a soft, spongy, or mushy lawn are poor soil composition, a build-up of stolons and rhizomes, clumps of dead grass (thatch), waterlogging from insufficient drainage, and a lack of airflow. Peeling back a small section of your lawn will help you to identify the root cause.

The first step to hardening up soft ground is to ensure that the soil is of good quality.

What Is the Cause of a Soft, Spongy, or Mushy Lawn?

Lawns are far more comfortable to walk on when they have some bounce. But there is a ceiling to the level of spongy that is acceptable, as excessive mushiness will end up ruining your lawn.

Mushy soil and sinking turf can be due to several reasons, including soil quality, thatch, and the root system of your grass species.


Good soil composition goes a long way to keeping your grass green and healthy. You need to know what the turf is growing on.

Clay soils are full of nutrients, but they’re a haven for grubs. Wet clay can make the soil feel soft and unstable and give you subsidence issues, which can then result in a space between the turf and soil.

Dense and acidic soils develop more thatch than loose and alkali soils. A frequent problem with hard soil is that the roots have less access to oxygen.

Stolons and Rhizomes

Warm-season grass such as Bermuda and zoysia grow out with rhizomes and stolons. Rhizomes are roots growing out to start a new stalk of grass. Stolons have the same goal but grow above the root system.

There is nothing wrong with stolons and rhizomes, but they can lift the turf from the soil. These root systems can also catch dead grass or make it difficult to cut to a consistent height. Both can lead to an increase in thatch.

The hardness of these horizontal root connections will add bounce to your step as you walk over them. Do not attempt to cut these node connections as you need to keep them intact for your grass to propagate.


Dead grass from mowing or from seasonal changes will clump together on top of healthy grass, to form a thick mat. This mat of dead grass will smother new grass, depriving it of sun, water, fertilizer, and oxygen.

Thatch can also cause the root system to separate from the soil, making it feel bouncy as you walk over it as it tries to grow up through the dead grass. Zoysia, tall fescue, and perennial ryegrass tend to produce the least amount of thatch.

Thatch is a perfect breeding ground for fungi and insects. Most grass diseases take over and infect from the top, turning the leaves brown. The infection will then turn downwards, after finishing with the dead grass, invading the greener shoots and the roots.


The roots of a dead tree or other decomposing organics under the grass can end up leaving voids behind. Water can fill these spaces, causing the grass to feel mushy and unstable as you walk over it.

Rain and irrigation water will dam up between the turf and soil, making the turf feel like you are walking on a waterbed. If this water barrier is left alone, for the roots to marinate in stagnant rainwater, the roots will rot.


A lack of air reaching the space between the turf and the roots will slow down the rate of decomposition of dead roots and the growth of new turf. Compressed soil will prevent the roots from absorbing nutrients and oxygen, even if they are abundant in the soil.

How to Firm up Your Lawn

Squishy lawns are not good for the health of your grass, so you should try to find out what it is that is causing it and fix it. There are several reasons why your grass feels spongy, and you can fix most of them with the following methods.


Step-by-Step Guide

1. Test

Use a soil pH meter to tell you if the soil is waterlogged. You may need to hold back on watering and improve the drainage.

A soil meter will also give you a better idea of the composition of the soil. You want to know if your soil is acidic with too much nitrogen or alkaline that needs more fertilizer.

2. Investigate

If you have done all the tests and all the right things, and the lawn still feels squidgy, peel back a small section and have a look. You can cut, peel back a small square of turf, and resod it without damaging the grass.

You may discover that someone planted fresh sod on top of an old lawn. Or you find that water is coming from a burst pipe, or a grub infestation is writhing between the roots.

3. Dethatch Schedule

Dethatching can be done year-round, but it is better to leave more aggressive thatching for the end of summer and the start of spring. These are the times when vegetation loses the most leaves and when the dead leaves begin to decompose.

4. Dethatch Tools

A rake is fine for regular dethatching work, and you can spend a few minutes a week pulling back the worst of the dead vegetation. Or, if you have a large lawn, you may want to invest in an electric dethatching tool.

An electric dethatching tool gives you height options so that you can choose how deep you want to scarify the lawn. Dethatching machines will also give you the possibility to collect all the thatch without dragging it across the lawn, as you would with a rake.

5. Aerate

Aerator shoes are an inexpensive maintenance solution for any lawn and well worth the small investment.

You can try an all-in-one aerator and dethatching machineOpens in a new tab., which maybe be the better option for extensive lawns. But in most cases, aerator shoes are more than capable.

Aeration shoes attach to the bottom of your existing shoes and drive 2-inch spikes deep into the turf as you walk. This improves drainage and helps nutrients and air to reach the roots, important when you have compact soil.

6. Drainage

If your soil is struggling to drain excess water away, aerator shoes will help. But for constant waterlogging after rainfall, you will need to install a drainage line. You should be able to do this without causing too much damage to your lawn.

Storm drains will give you the chance to drain away large puddles of water. You want to rid the lawn of puddles before they have a chance to sink in beneath the turf and cause the grass to float.

The process involves burying a corrugated drain tube under the grass. This piping will connect a small storm drain coverOpens in a new tab. sunk into the lowest part of your lawn to your main drain system.

Joshua Milton

I want to share everything I know about home improvement in order to help you. Whether you're a home enthusiast or an industry professional, I have the information that you need.

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