How to Use Mushroom Compost in Raised Beds?

Mushroom compost is often used as a soil amendment, it can improve water retention ability of your growing medium and organic matter in it can enrich the plant soil.

While you can use mushroom compost in raised beds, remember that acid-loving plants don’t like mushroom compost.

Nutrients in spent mushroom compost are 1-2% nitrogen, 0.2% phosphorus and 1.3% potassium and other trace elements. (Source)

If you’re planning a raised bed for growing vegetables, then adding mushroom compost or substrate will be an excellent way to enhance the soil in raised bed by promoting healthy plant growth.

Apart from veggies, you can grow ornamental plants in raised beds with mushroom compost as soil amendment.

What is Mushroom Compost?

mushroom compost in raised garden bed

In simple words, mushroom compost is leftover organic matter of mushroom growing. It is widely used to improve soil texture and water retention of poor soil.

It includes various materials like poultry manure, hay grass, horse manure, soybean meal, corn cobs, peat moss and pulverized limestone.

It is a nutrient-rich blend that provides an ideal environment for mushroom growth and is also highly beneficial for enhancing soil fertility in gardening and horticulture.

Leftover from mushroom farming, it is pasteurized to eliminate pathogens and weed seeds.

After subjecting it up-to 170F for several weeks, obtained mushroom compost will be free from residue insects and harmful bacteria.

This mix of various natural materials and animal waste contains important nutrients like nitrogen, phosphorus, potassium, and small amounts of other minerals.

It also possesses a high organic matter content, which improves soil structure, moisture retention, and microbial activity. These qualities make mushroom compost an excellent soil amendment for various gardening purposes, including vegetable gardens, flower beds, and container plants.

Why Use Mushroom Compost?

Wide-range of materials in mushroom compost makes it ideal to amend the soil.

Being cheap when compared to nutrient rich potting soil, mushroom compost can be easily obtained from local mushroom farms.

Below mentioned are its benefits:

1. Rich in nutrients

Essential nutrients like nitrogen, phosphorus and potassium, including trace minerals are packed in mushroom compost that can enrich your garden raised beds.

These nutrients will give your plants initial boost to enhance leaf growth, promote the growth root system and encourages plant to produce blossoms and fruits.

2. Improves soil

Adding mushroom compost will enhance soil fertility and its structure. Organic matter in this spent mushroom compost improves soil texture, water drainage and aeration.

It also increases the water retention ability of growing soil in raised beds, which can reduce watering frequency.

Moreover, mushroom compost promotes beneficial microbial activity in the soil, creating a favourable environment for plants.

3. Can be used as mulch to suppress weed growth

When used as mulch, mushroom compost acts a natural barrier that restricts weed growth.

When the soil surface is covered with mushroom compost, it limits sunlight exposure to weed seeds, thus hindering their germination and growth.

Suppressed weed growth eventually reduces the competition for nutrients, water, and sunlight, benefiting the plants.

4. Eco-friendly recycling

Mushroom substrate offers a sustainable and eco-friendly way to repurpose leftover of farming and organic waste materials.

Using mushroom compost to garden beds helps to divert these leftovers away from landfills, effectively utilizing them in a productive manner.

By doing so, you’ll reduce the overall environmental impact and contributes to the promotion of a circular economy.

5. Improves Soil pH

Apart from improving soil texture, mushroom compost makes your soil neutral to alkaline.

Mushroom compost has chalk that exhibits alkaline nature. So, before adding it to the soil, you are recommended to remove large pieces of chalk and use it moderation.

Note: Avoid using mushroom compost to plants that love acidic soil.

6. Other uses

It is suitable for vegetable gardens, flower beds, container plants, and even lawns. You can apply it as a top dressing, amend with the poor soil during planting, or mixed with potting mixes.

Also Read: How to grow ivy gourd in containers?

Using Mushroom Compost in Raised Beds

Spent mushroom compost is the inexpensive way to fuel your organic gardening experience.

Apart from fitting your gardening budget, it is packed with beneficial macro and micro nutrients that can enhance plant growth.

As mentioned earlier, this slow-releasing organic fertilizer is leftover material from mushroom farms.

Though it has name mushroom, this compost does include any mushroom.

It undergoes pasteurization method to remove possible insects, bacteria and weeds.

Not just adding nutritional value, mushroom compost can improve soil pH and drainage ability of the growing medium.

If you’re looking to fill your raised gardening beds, then mushroom compost can be the most inexpensive way.

How to Use Mushroom Compost in Raised Beds?

Though it improves drainage and water retention abilities of the growing medium, adding too much spent mushroom compost can result in root rot and overwatering.

Below mentioned is a step-by-step guide on how to use mushroom compost in raised beds:

1. Prepare the gardening bed

To avoid weed growth and to ensure healthy growth of the plants, you must clean and remove of any weeds.

If needed, remove any existing soil or mulch to create a fresh planting space.

2. How much mushroom compost should be added?

Calculate the amount of mushroom compost needed based on the size of your raised bed. Aim for a layer of compost that is about 2 to 3 inches thick.

3. Incorporate the compost

Fill raised garden bed with old potting soil and then add garden soil.

Using a gardening fork gently work the garden soil and spread the mushroom compost evenly over the surface of the raised bed.

Integrating compost with the existing soil will ensure proper nutrient distribution.

4. Avoid direct contact with young plant roots

Take care to keep the mushroom compost away from direct contact with the roots of young or delicate plants. Create a slight buffer zone by leaving a small space between the plants and the compost.

5. Water thoroughly

After applying the mushroom compost, water the raised bed thoroughly. This will help settle the compost and ensure that the nutrients are available to the plants.

6. Monitor soil moisture

Check moisture levels in the raised bed by inserting your index finger.

If you find sticky soil, then allow the growing medium to dry between watering.

7. Add other amendments

As excess mushroom compost can either lead to root rot or alkaline the soil, you’re recommended to mix organic matter like decomposed compost or well-rotted manure to balance soil’s eco system.

8. Mulch the surface

Consider adding a layer of organic mulch, like straw or wood chips, on top of the raised bed. This will help conserve moisture, suppress weeds, and provide additional nutrients as it decomposes.

Remember to periodically assess the overall health of your plants and adjust the frequency and amount of mushroom compost application as needed.

By adding mushroom compost in your raised beds, you can improve fertility of the growing medium and provide an ideal environment for plant growth.

What does mushroom compost have in it?

It is mixture of different material that is used in farming to enrich the growing soil. Mushroom compost has manure of poultry, cattle or horse, hay, straw, crushed grapes, peat moss, lime, gypsum, cocoa shells, corn hubs and other organic substances that enhance growth of your plants in the raised garden bed.

Is mushroom compost high in nitrogen?

Spent mushroom compost is obtained after mushroom farming. It does have nutrients like nitrogen, phosphorus, potassium and other minerals.

According to American Mushroom institute, this slow-releasing fertilizer has limited amount of nitrogen which is 1.12 percent nitrogen, 0.67 of phosphorus and 1.24 of potassium.

Though it is not high, adding this organic matter will improve soil texture along with its nutritional value.

Will mushroom compost kill grass?

Soil pH does impact weed growth. Using mushroom compost improves soil pH and it covers the top layer of the soil from sunlight. Thus, it restricts germination and growth of weeds.

You can read more on soil pH and weeds here.

What does mushroom compost do to soil pH?

As this slow –releasing fertilizer has variety of materials, mushroom compost with chalk (lime) exhibits alkaline nature.

When added to the soil it increases pH, making it favourable for plants that like alkalinity.


You can use mushroom compost in raised beds, in which you can grow vegetables and ornamental plants.

You can also grow indoor plants that love alkaline soil.

Acidic soil loving plants won’t grow in raised garden beds with mushroom compost.

To reduce the impact of alkalinity, you’re advised to remove big chunks of chalk and add other soil amendments like well-rotten manure to the growing soil.

You can either buy mushroom compost from local farm or make your own mushroom by adding wheat straw, fresh horse manure, gypsum and other organic materials to the compost heap.