Mushrooms Growing In My Raised Garden Bed: 6 Problems+Fix

You might get annoyed to see unplanned mushrooms growing up in your raised garden beds. The good news is that mushrooms hardly cause any harm to the soil and plants.

Mushrooms growing in the raised garden beds indicate that the soil is healthy, moist, and rich in organic matter or nutrients. They even help to improve the soil’s quality by breaking biomass in the soil. But some toxic mushroom varieties act as a threat to other vegetables and plants.

If you are worried about mushrooms in your raised garden beds, this article will help you know every possible reason behind their growth, along with the possible solutions and prevention.

What are mushrooms exactly?

Mushrooms are the reproductive structure produced by different fungi networks extending through the soil.

They are often classified as a spore-bearing fruiting body of a fungus.

The huge fungal networks are usually made up of root-like structures called mycelium, which is the main reason behind a fruiting body of a mushroom.

Most mushrooms that grow in raised garden beds are usually non-toxic and even provide nutrients to the plants.

But there is also a certain type of wild mushroom that can be poisonous. 

Let us discuss this in detail.

Are mushrooms beneficial for raised garden beds?

Mushrooms are beneficial to raised bed gardens in different ways:

• Mycelium fungal networks actively produce nutrients like Nitrogen, Phosphorous, and Potassium, making the soil nutritious.
• Mushrooms help to break down the large and complex particles of organic matter easily. This improves the soil’s quality and increases the rate of nutrients from organic matter.
• Mycelium and plants have a symbiotic relationship that helps them communicate. This means mushrooms help the plants get early warnings of pest attacks and diseases.
• They also encourage the plants to grow fast and stay healthy.
• Mushrooms also increase the ability of a plant to absorb nutrients and water from the soil.
• They also reduce stress from extreme climate and improves drought tolerance. 

But most gardeners still don’t like mushrooms in their raised garden beds because it doesn’t look good.

Even if some of the mushrooms are harmless, it’s better to get rid of them after some time.

How are some mushrooms dangerous for plants?

Even if toxic mushrooms are rare, there is a possibility that they can still grow in your raised beds.

Few mushrooms can be harmful to plants.

Let us see the drawbacks:

• Mushrooms give a bad appearance in the raised garden bed.
• Continuous toxic fungi growth in the soil can damage plants and vegetables. 
• Toxic mushrooms can harm kids and pets and severely upset their stomachs.
• Mushrooms are also a sign of overwatering. Damp soil gives the most favorable conditions for spores to develop. 

Wild mushrooms are usually difficult to figure out.

They have a different rotted and acrid smell, while non-toxic ones give a refreshing smell.

Here is the list of poisonous mushrooms that can grow in raised garden beds:

• Destroying Angels
• Conocybe filaris
• Death cap
• Autumn skullcap
• Webcaps (Cortinarius species)
• Deadly Dapperling
• Podostroma cornu-damae

However, they are very rare, but it’s better to identify the type of mushrooms growing in your raised bed to avoid further problems.

Why are mushrooms growing in a raised garden bed?

Several reasons can be behind mushrooms growing in your raised beds.

Sometimes, raised garden beds provide the ideal condition for mushrooms to grow.

Let’s discuss this in detail.

A lot of moisture

Even though raised beds support better drainage than in-ground beds, they still need to be watered well.

The soil in the raised bed garden is often moist, providing an ideal growing condition for mushrooms.

Mushroom growth will happen in the raised garden bed if it’s frequently suffering from overwatering.

Excess moisture in the soil provides a perfect growing environment for several fungi to sprout.

Alkaline soil

Mushrooms thrive in alkaline soil, which means the soil has a high amount of calcium, magnesium, and sodium.

If the soil has a pH level of 7.70- 8.91, it becomes preferable for mushrooms to grow.

It mostly occurs due to overfeeding.

Shaded areas

Mushrooms can grow if your raised bed is kept in a shaded area that doesn’t receive that much sunlight and stays wet frequently.

Mushrooms don’t require light to thrive as they are fungi.

They love to stay in a shady environment and can even grow without any photosynthesis and chlorophyll.

Warm soil

Mushrooms like to grow in somewhat warmer soil.

The raised bed usually gets warmer faster than the ground bed, which provides a favorable growing condition for mushrooms.

Poor soil drainage

If your raised bed is compact and has poor drainage, it becomes highly probable for mushrooms to grow.

The raised bed becomes tight and compact if it has high clay soil and low organic matter. 

Rich in organic matter

One of the main reasons why mushrooms grow in your raised bed is because the soil is rich in organic matter.

Mushrooms are fungi that like to thrive in decaying organic matter.

Raised garden beds usually contain chunky mulch, wood chips, or timber that helps the mushrooms sprout. 

Growing medium for wild mushrooms

Wild mushrooms need a different growing medium to grow in raised garden beds.

There are some of the reasons given below:

• High compost
• Mulch
• Dung manure
• Decomposing leaves or other plant parts
• Deceased vegetation under the raised bed soil

How do you get rid of mushrooms in raised garden beds?

Whether mushrooms are harmless or not, it’s best to eliminate them.

If you don’t want mushrooms in your raised bed, you need to take immediate steps to eliminate them when they sprout.

The best possible solutions are given below to remove them entirely from your raised bed.

1. Reduce watering in your raised bed

As mushrooms love to thrive in damp conditions, it is better to water your raised bed as per the plant’s needs.

Avoid overdoing it, as fungus can easily develop in moist places.

Don’t water the plant until and unless the soil feels dry.

Always check the moisture level before watering.

Ensure the plants growing in the raised bed receives sufficient sunlight and airflow.

2. Aerate your raised bed

Providing enough air circulation in the soil can eliminate mushrooms growing in your raised garden bed.

Try to aerate the soil with an aerator so that there is enough air and oxygen inside the soil.

This will help kill the fungus that is thriving underneath your raised garden bed. 

3. Make sure the soil dries up quickly.

The quality of the soil plays a major role in mushroom thriving.

For example, clay soil retains more moisture, while sandy soil drains more quickly. 

If the soil is compact, try to add some sand, compost, perlite, or vermiculite to make it more draining. 

This will help the soil to dry much quicker.

Hence, mushrooms will stop growing on their own because of dryness. 

4. Reduce organic matter

Try not to provide any organic matter to the soil.

You can use hydrogen peroxide to remove all the organic matter in the soil. 

This oxidation helps destroy all bacteria, fungi, pathogens, and viruses and makes the soil fully sterilized. 

5. Provide proper drainage

If your raised bed doesn’t support proper drainage, it can frequently suffer from overwatering.

If you have a taller raised bed, it will hold more water.

Try to choose the correct elevation for your raised bed. 

To solve this issue, build a raised platform just like steps around the raised bed for accessing the bed easier.

After completing the elevation part, build a raised bed liner.

This helps the water to drain away quickly from the soil.

You can use canvas, hardware cloth, and landscape fabric for lining your raised bed, along with proper drainage. 

Make sure to avoid plastic liners, as they will not allow any water to drain from the soil. 

6. Pull up all the mushrooms.

As soon as you notice mushrooms in the raised bed, you should immediately remove them by pulling them off with your hands.

Leaving the mushrooms for a longer time in your raised beds can make them spread more. 

While removing the mushrooms, the spores destroy, which is responsible for the growth of fungi.

Make sure to use gloves while picking them off or wash your hands after doing so.

7. Throw them properly

After picking all the mushrooms from your raised beds, be careful while throwing them away.

Make sure you don’t throw mushrooms in your composite pile.

Instead, please bring a bag, bin them there, and then pack it tightly so that no spores will become airborne.

After the bag is full, you can throw it far away from your raised bed to prevent fungi from spreading.

8. Use dish wash soap

After handpicking mushrooms from the raised beds, make a solution with a few drops of dish wash soap and water.

Pour the solution inside the hole where the mushroom existed to prevent any further growth in the future.

9. Clean the mulch surface

It is common to see mushrooms growing on the mulch surface because it retains much moisture.

To clean the mulch, mix it with 1 gallon of water and 1 tablespoon of baking soda, then mist it all over the mulch surface.

This will help to kill the mushrooms developing in those areas. 

10. Use Nitrogen fertilizer

Nitrogen fertilizer is the best way to remove mushrooms because it helps to increase the decomposition rate of the compost pile.

By destroying the mushroom’s food, they won’t be able to feed on anything that will eliminate their further growth.

11. You can also use sulfur powder.

Sulfur powder helps in preventing mushroom spores from developing.

If you notice that nothing is stopping mushrooms from growing in your raised bed, then you can follow this method. 

This helps the soil lower the pH level, making the soil completely alkaline, which is an unfavorable environment for mushrooms.

Can you use a fungicide to kill a mushroom?

Many think of using a fungicide to eliminate mushrooms in their raised garden bed.

But it’s going too far.

Using fungicides means applying chemicals to your raised bed that can damage the entire soil and the plant.

Also, it is not effective in killing mushrooms.

It’s better to use vinegar instead of that. 

Vinegar is known as a natural household fungicide.

The acid present in the vinegar will help to kill the mushrooms entirely.

How to prevent mushrooms in raised garden beds?

Removing mushrooms is relatively easy in most garden beds, but preventing mushrooms can be very challenging.

Now, let us discuss how you can prevent mushroom growth:

• Maintain good drainage in your raised bed garden to avoid overwatering issues. To improve, you can add compost and other soil amendments like coco coir, worm castings, grass clippings, greensand, cornmeal, straw, etc., and mulch the soil surface frequently. 
• Aerate the soil from time to time with the help of an aerator. This will help to provide proper airflow throughout the year. 
• Try to provide as much sunlight to your raised bed. If trees or bushes block the surface and provide shade, try to remove them.
• Keep your raised bed clean, remove any decaying matter like decomposed leaves, dung, etc., and always maintain a clean environment. 
• Don’t overwater the raised bed, as it can create a damp environment frequently. Try to check the moisture level with a moisture meter to water the plant, and don’t overdo it at any cost.
• Try to use only well-rotted manure, which includes horse or cattle manure, as it has the lowest nitrogen content to avoid any development of fungus. 

Final words

It is common to see mushrooms growing in your raised bed, but it doesn’t cause any harm in most cases. So you don’t have to stress about it. 

You can keep mushrooms if you want, as it provides certain benefits to the soil. But, it is better to remove them. So, as soon as you notice any mushrooms, immediately pull them off your raised garden bed and throw them away to avoid spreading the fungus.

If you have pets or children, try to keep them away from the mushrooms. 

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Reference: ScienceDirect, American Society of Agronomy, Noble Research Institute, Soil for Raised Beds, Raised Bed Gardening.