What Causes Grass Bubbles – How are They Formed?

Grass bubbles are caused by water trapped beneath the grass in your lawn. In most cases, lawn bubbles are formed after a period of excess rainfall or because a water pipe has burst beneath the surface.

Often, grass bubbles form in areas of your yard where plastic has been laid beneath sod or grass. This is sometimes done in areas with poor soil—plastic is laid down and new topsoil is laid before planting. This is a prime area for water to collect and create a grass bubble or “lawn blister.” In some cases, grass bubbles can form even where there is no plastic beneath the grass.

What Causes Grass Bubbles?

What is a Grass Bubble?

A grass bubble is commonly a trapped pocket of water beneath the grassy layer in your lawn. While large grass bubbles infrequently occur in some cases (mostly on golf courses and similar areas) they can form in your yard.

It may not just be water in your grass bubble, while not common in most regions, some grass bubbles contain methane gases released by decomposing plant matter. This is most common to cold, subpolar regions. Chances are, a bubble in your yard is full of good old H2O.

How are Grass Bubbles Formed?

Grass bubbles are formed when water is trapped beneath the grass and cannot drain away. Periods of intense rainfall and heavy storms can flood your yard with more water than it can drain away. If there has not been heavy rainfall and a grass bubble has formed in your yard, it is likely due to a burst water main that is pumping water into the soil beneath the surface.

Grass bubbles are most common where plastic has been spread prior to adding topsoil and grass. The water becomes trapped between the plastic and the soil beneath, creating a pocket of water like a grass waterbed.

In the absence of plastic, grass bubbles can form beneath tightly growing grass and sod. When the grass and thatch are thick enough, an excess of rainfall can become trapped between the grass and the soil beneath. The grass essentially floats on top of the water.

Can Bubbles Kill Grass?

Yes, grass bubbles can be harmful to grass. Any excess of water can “drown” grass. Grass bubbles can essentially uproot your grass. Without ground contact, the roots are not able to take in essential nutrients from the soil. If a grass bubble is left to its own devices, it will kill your grass.

Are Grass Bubbles Dangerous?

Grass bubbles are not especially dangerous—they generally are not hiding sinkholes or anything of that type. However, they can contain large quantities of water, which you may not want flooding your yard.

If you encounter a grass bubble and want to get rid of it, carefully plan drainage away from the bubble. First, dig any necessary trenches. Then, puncture the grass bubble while doing as little damage to your grass as possible. If you create an extremely large puncture or multiple punctures, you can cause damage to your lawn and garden when getting rid of a grass bubble.

Water Bubbles in Grass

Grass bubbles, or lawn blisters, are not especially common, but a period of intense rainfall or a burst water pipe underground can cause a waterbed-like bubble in your grass. This is caused by water trapped between the ground and your grass. Your grass essentially “floats” on top of the trapped water. In areas where plastic has been laid beneath the grass, there is a much larger risk of grass bubbles.


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