Why is My Lawn Cracking? (Causes and Solutions)


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A lawn can bring beauty to any space by creating greenery and providing a space to play and carry out our recreational activities. However, cracks on the lawn can be unsightly and can negatively affect its esthetics.

Cracks on lawns are caused by a lack of moisture and soil type. In soils with a higher ratio of clay, drought conditions can cause the moisture content within the soil to drop very low. The soil contracts as the moisture is removed. This contraction pulls the soil apart and as it shrinks, causes cracks on the surface.

The key to maintaining a beautiful lawn is preserving the soil’s moisture content. This would not only prevent cracks but promote healthy lawn growth.

In this article, we are going to discuss the causes for cracks on the lawn as well as the solutions you can employ to fix the problem.

What Causes the Lawn to Crack?

Cracks on lawns are all related to the soil’s moisture content and the environmental conditions that the soil is exposed to.

Here are 5 main causes which contribute to cracks on a lawn. 

Soil Type

Clay silt and sand

The soil type has a major role to play when it comes to retaining and releasing moisture.

Soil differs greatly from one geographic region to another, but all soil falls into one of three classifications: clay, loam, or sand or a mixture of each.

In most cases, lawns that are plagued by cracking consist mainly of clay soils where the ratio of clay is much higher compared to the sand and loam.

Clay is simply stone material that has been worn down to microscopically small silicate minerals which stack up upon each other. 

Clay soils are dense and slow draining because of how closely the particles are located from each other.

Clay soil tends to crack because it’s too dry. 

When clay soil is hydrated the water seeps in between these silicate sheets which in turn causes the soil to expand. On the other hand, when the soil is dehydrated, it loses its moisture content as the water in between the silicate sheets evaporates. 

As a result, the soil begins to shrink and pull apart causing visually noticeable cracks on the surface.

I used this cheap soil improver in places on my lawn where the grass died and it worked wonders.

Scotts Turf Builder Thick'R Lawn Sun & Shade
dew on grass

Grass Too Low

The lawn grass itself acts like a barrier to the sun and the effects of heat on the surface of the soil. 

The length of the grass blades has a similar effect as if you were to mulch a stretch of dirt as it protects the soil surface and helps retain some moisture content within the soil.

Another unforeseen benefit of having longer grass blades is that it promotes dew formation.

Longer grass blades, approximately 3 to 4 inches, will allow more dew to form during the morning periods.

Therefore leaves with a larger surface area will cause more dew to form and also fall onto the soil which will help in maintaining the soil moisture content.

However. a more aesthetic and practical lawn height should be between 1 to 2 inches with a higher grass density.

Soil Compaction

Whether it is clay soil or some other well-drained soil, whenever force is placed on top of the soil it will cause it to become compact. 

The compaction forces the soil particles closer together which will restrict water absorption. 

For this reason, lawns that have been used extensively for playing football or other sports tend to have higher compaction than lightly used lawns.

When water is added it would tend to run off easily or just form puddles on the surface.

This is why water might be sitting on top of your soil whenever it is watered or when it rains.

See out article on how long should soil stay wet after watering.

Too much Fertilizer

Adding too much fertilizer can cause grass to get burnt out and become sparsely populated.

This effect would be similar to the previously explained where the grass blades are too low.

The surface of the soil would be exposed to too much sunlight and heat which will cause the water from the soil particles to evaporate more easily.

Soil Dryness

Soil dryness, as a result of evaporation, is the main cause of why soil cracks.


As with other causal factors, cracks will show up on the soil’s surface as a result of moisture removal which leads to soil dryness.

To take the guesswork out of determining how much moisture your soil has, you can use this cost-effective soil moisture meter from amazon.

XLUX Soil Moisture Meter

Here are some reasons why the soil may be dry –

  • Lack of watering

    Watering the lawn should be a routine task and if it’s not done in a timely manner or if the watering schedule is neglected you may find the lawn cracking as a result.

    For this reason many people adopt automatic sprinklers which come on routinely, at a predetermined time and apply a certain amount of water to the lawn.

    When this strategy is used you will almost never see any signs of  cracking as the soil is kept well hydrated at all times.

    Additionally the schedule can be changed to suit the weather conditions, for example, as summer months approaches and there are longer, hotter periods of daylight.
  • Change in Weather conditions

    Water is pulled easily from the soil on a hot day. This evaporation causes the soil to shrink as the moisture evaporates from the surface.

    Moving from spring towards summer the amount of sunlight and hotter daylight would increase significantly as you move closer to the July to August months.

    Hotter dry spells where there is a lot of sunlight and little rain can have a big impact on the soil moisture content.

    Additionally, where there are higher winds, surface evaporation would also increase and would add to the effect of evaporation of moisture from the soil.

See our article on how weather conditions affects potting soil.

Sprinkler
  • Watering at the wrong time of day

    When water is applied to a lawn or soil it has a finite amount of time before it is actually absorbed into the soil.

    During this time period other environmental factors may come into play which may reduce the amount of water that actually gets into the soil.

    Watering during the day will not be such a good idea as the heat from the sun coupled with the effect of the wind can significantly reduce the effectiveness of watering the lawn.

    This is why it is recommended that watering the lawn and soil should be done on late evenings after 6pm or early mornings before 10am.

    For good reason, this ensures that the effects of heat caused by the sun and the winds that pick up during the day doesn’t nullify the effects of the water applied to the soil.

    Watering lawns should be done via a sprinkler for ease and efficiency as it will evenly distribute the water over the surface of the lawn for a period of time.

How do you Fix Large Cracks in the Lawn?

Large cracks appear in the lawn due to a lack of moisture in the soil. To fix this you should reapply water to the soil for the silicate sheets within the clay to expand.

In some cases where the cracks are too large and when water is applied you may notice that it does nothing.

This is because the cracks have created channels beneath the soil which would allow the water to flow freely to other areas without even getting a chance to rehydrate the soil.

Large cracks can be fixed by filling the crack with a loam mixture with a 2:2:1 ratio of sand, silt and clay. The filled area and the surroundings should be watered thoroughly and allowed to sit for a period of time for the water to be absorbed into the soil.

However, when dealing with lawn and soil cracks, prevention is key and the causal factors listed above should be considered when employing preventative measures.

Here are some preventative measures.

Preventative Measures
Soil typeCheck the soil type and ensure it is of a  loamy nature
Grass blade lengthGrass blades should be between 1 to 2 inches
Soil CompactionMinimize traffic on the lawn areas to prevent soil compaction
WateringApply a consistent watering schedule of 2 to 3 inches of water per week is ideal
FertilizerDon’t over-apply fertilizer which may run the risk of killing the grass and exposing the soil

How do I keep Moisture in my Lawn?

How do you keep clay soil from cracking? The only way to keep a lawn from cracking is to keep moisture within the soil. 

This significantly reduces a stressed lawn and the signs and symptoms associated with stress.

Moisture levels can be promoted in the soil by creating a loamy soil mixture for the grass to grow. A loam mixture primarily consists of sand, silt, and clay which makes use of the properties (particular distance) of each soil type.

The Ideal Loam Soil Mixture

The ideal soil mixture for lawns is a medium loam, with proportions (by weight) of 40% sand, 40% silt and 20% clay. This mix holds nutrients, the right amount of moisture within its structure and allows excess water to drain freely.

The Sand is the largest-sized particle within the mix and allows for the maximum amount of water to be let out. 

Sand has a particular distance that ranges between 0.074mm to 0.42mm for coarse sand and 0.42 to 2mm for fine sand.

Additionally, it has the least amount of nutrients within its structure as most of it is leached as the water passes through it.

The silt consists of medium-sized particles with slightly better water retention than sand and also has more nutrients than that clay. It has a smooth or floury texture. 

This is mainly due to the distance between particles which ranges from 0.074mm to 0.005mm.

Lastly, the clay in the loam mixture has the highest amount of nutrients within its structure since it does not readily allow water to freely drain. 

The particular distance in clay is the smallest of the three and ranges, 0.005mm to 0.001mm between particles.

Clay silt and sand

Consistent Watering

In order to keep the moisture within the soil for lawns, you should have a consistent and routine watering schedule that would provide the required amount of water to prevent the soil from cracking.

Applying water via a sprinkler system preprogrammed to come on for about two or three times a week for 15 minutes should provide enough water to promote healthy grass root growth.

This watering schedule should deliver between 2 to 3 inches of water to your lawn depending on the number of sprinklers you employ during the process.

A Simple Way to Test your Soil’s Contents 

A very simple way to test the structure of your soil is to 

  1. place a sample of soil into a glass jar filled with about 50% water.
  2. Shake the soil and water until the soil completely dissolves into the water. The resulting mixture would look dark brown as it swirls and mixes.
  3. Give the mixture some time for the different soil types to settle.
  4. As the mixture begins to settle you would notice that the different types of soil will begin to stratify into layers.

Starting from the bottom you will notice small stones or gravel then the soil clay as it is the heaviest. This is then followed by the sand and then the silt, which is the lightest of them all. 

The remaining water which is not absorbed by the soil then sits at the top.

A measurement of the height of the different layers will give you a good idea of the composition of the soil in your lawn.

This will help in evaluating whether or not you should amend the soil by adding sand or silt to the mix. If you choose to go that route.

Why is my Grass Cracking?

This is a common query used when someone is looking for the reason why the lawn or soil beneath it is cracking.  

It really reverts back to the same answer which is lack of proper soil water content due to the type of soil, weather conditions or the grass density planted on the soil.

JayLea

JayLea has a passion for plants and has been gardening since 2015. He has valuable knowledge about gardening and houseplant care and can answer everyday practical questions that every plant owner has.

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