Mushrooms Growing Under Pavement? (5 Things To Do)

Gideon Zielinski
by Gideon Zielinski
Mushrooms may look cool, but they are often a sign of something rotting, even when they grow under the pavement. You can remove mushrooms from under pavement several ways, but you’ll generally need to tear up the driveway or sidewalk. Whether you tear up the pavement or let them die, let’s take a look at what you should do when you have mushrooms growing under the pavement.

A mushroom growing through your pavement is an odd sight. At first, you might be impressed – how did a squishy little mushroom lift the pavement? However, then you realize these little fungi are destroying your driveway and, as phenomenal as it is, you must fix the problem.

Mushrooms will grow under your pavement if there are remnants of rotting material. Sometimes the mushrooms will even push through, destroying your sidewalk or driveway in the process. To fix this, you must remove the mushrooms’ source. That means either tearing up the driveway and clearing the debris underneath, or letting the organic material rot away entirely.

We will look at your options in the sections below and give you some tips on ridding your pavement of mushrooms.

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How to Stop Mushrooms from Growing Under Your Pavement

If you recently noticed your pavement bubbling or even cracking due to mushrooms, here are five things you can do:

  • Wait until the organic material has decomposed completely
  • Spray the area with a fungicide 
  • Dig up the damaged spot and patch the pavement
  • Remove nearby trees and roots – if they are the source 
  • Dig up the asphalt and replace the soil below with a deep layer of sand and gravel

1. Wait Until the Organic Material Has Decomposed

The easiest thing to do is to wait for the fungus to finish its job. A mushroom is an offshoot of the fungus below. The fungus is decomposing something in the ground. This is usually something rotting at the soil’s surface, like an old tree stump or sawdust from a previous project. Eventually, the fungus will have finished eating the dying material, and the mushrooms will go away.

You need to weigh your options. On the one hand, the mushrooms may not be doing a ton of damage, so a repair might be more expensive than it’s worth. However, perhaps the mushrooms have ravaged your driveway, leaving you with a pile of rubble. In this case, you’ll need to replace it.

Thankfully, there are more options than just waiting.

2. Spray the Mushrooms with a Fungicide

Though treating the pesky mushrooms with a fungicide would seem logical, this idea probably won’t work. The reason it likely won’t work is that mushrooms are connected to a deeper source. Your fungicide isn’t going to penetrate deep enough or span far enough to kill the mother fungus.

With this said, if you have some fungicide lying around, you will probably at least try to spray the mushrooms. Though it’s not the most effective thing to do, if you spray them, dig out the mushroom and spray the fungicide as close to the root as possible. Doing this will be your best shot at stunting the growth of further mushrooms.

3. Patch the Area Damaged by Mushrooms

If you notice mushrooms are lifting your pavement, you may want to remove the raised portion and clear the area of any mushrooms or tree roots growing underneath. Unfortunately, there is no simple way to stop mushrooms from growing under your pavement without excavating the site.

If you choose to do a patch job, know that mushrooms might still grow underneath your pavement. If the mushrooms’ food source remains, there is always a chance that mushrooms will return when conditions are right.

For more information on patching up your driveway, see our article on repairing holes and depressions in your asphalt driveway.

4. Remove Nearby Trees and Roots

Most of the time, the source of your mushrooms is hidden beneath the pavement. However, some trees establish a symbiotic relationship with certain types of mushrooms. The mushroom helps provide moisture to the tree while the tree gives the mushroom needed nutrients.

In some cases, there could be roots from a nearby tree reaching underneath your driveway. The roots may have partner mushrooms, and these mushrooms might damage your driveway when they grow. If this is the case, consider removing the tree. When the tree dies, it will no longer provide the needed nutrients for the mushrooms to survive.

However, even if you remove the tree, the roots may begin to rot and will need to be pulled up – or they will produce mushrooms of their own. Also, you may like the tree, and removing it might be more of a hassle than the mushrooms under your pavement.

5. Dig Up the Driveway and Relayer the Foundation with Sand and Gravel

A complete repair of the foundation of your driveway is the proper fix. To do this, you will need to completely excavate your driveway, dig down about 12 inches, and lay a deep gravel and sand base. Mushrooms thrive near the surface, so digging down into the soil and replacing it with inorganic material will significantly reduce your risk of further mushrooms.

This option is the most permanent, and also the most expensive. Weigh the pros and cons of your decision. If you’ve had lots of problems with mushrooms, then a complete repair is your best option for a solid driveway or sidewalk.

After you dig your pavement up, be sure to remove any organic material that could be causing the fungus to proliferate. Here are a few things that cause mushrooms to grow:

  • High moisture
  • Old rotting wood 
  • Tree roots 

Be sure the foundation of your driveway is clear of these before adding new cement. To combat moisture, you may want to build your driveway with a slight slope to encourage proper drainage.

How Can Mushrooms Grow Through Pavement?

Mushrooms can grow through your pavement due to high vertical pressure and strength. Some mushrooms can push through asphalt because they grow straight up. Mushrooms don’t like growing any other direction. This concentrated force, along with an intricate cellular pattern, allows them to exert extreme upward pressure.

You may consider replacing your asphalt driveway with a thick concrete driveway, as mushrooms have a more challenging time penetrating reinforced concrete.

We answer more of your mushroom questions below.

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Related Questions

How Do You Stop Mushrooms From Growing in your Lawn?

You can stop mushrooms from growing in your yard by removing them in the evenings before they have a chance to grow large enough to spread their spores. This will limit their spread. You can also use a commercial fungicide. Also, ensure that your lawn can effectively drain. Mushrooms thrive in moisture. If your property is too damp, mushrooms will grow. Finally, clean up anything that might provide a food source, like rotting branches.

How Do You Stop Mushrooms Growing in Gravel?

If you have mushrooms growing in your gravel path or driveway, your gravel has probably become diluted with too much dirt and organic material. To stop mushrooms from growing in your gravel driveway or walkway, you will need to remove the fungus’s source and make your gravel base deeper. See our article on fixing a gravel driveway overrun with grass.

How to Stop Mushrooms Growing on Cement?

Mushrooms will grow on the surface of your cement when there is a build-up of grime. To remedy this issue, you will need to clean the area often to prevent the dirt and rot from aggregating on your cement. If deep cracks allow the mushrooms to grow from the ground below, you will need to clear out the gaps and repair them with a strong cement patch.

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Gideon Zielinski
Gideon Zielinski

Gideon is a writer and hobby woodworker. He enjoys working on projects small and large-everything from crafting boxes and benches, to replacing carpet and landscaping a yard.

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