Mushroom Compost: A Complete Guide for Organic Gardeners

What is mushroom compost? This complete guide to mushroom compost will explain what this soil amendment is, what it does for your vegetable garden, and its many benefits.

We’ve used mushroom compost in the past here at Seven Oaks Farm, the inspiration for Home Garden Joy. In the past, we purchased bags of it from our friends and neighbors who have a trucking and farming business. This year, we bought it in bulk and added about four inches of it to the top of the raised beds. The results have been a tremendous harvest that surpassed our wildest dreams.

What Is Mushroom Compost?

Mushroom compost is a type of organic compost made from the materials used to grow mushrooms. It’s essentially a byproduct of the mushroom farming process. The primary components of mushroom compost typically include:

• Straw: Often used as a bedding material for mushrooms, or it may be leftover from horse stable bedding. (Many stables use pine or wood shavings for horse beddings, but some may still use straw).
• Manure: Horse or poultry manure is typically part of the mix, but we have heard from friends that cow manure may also be part of the blend. It depends on where you purchase it from. Aged manures add vital nutrients to the compost.
• Gypsum: Added to help balance the pH and improve the texture of the compost.
• Other organic materials: Depending on where the compost comes from, it may include other composted plant materials.

So this compost is actually mushroom soil, or the soil in which mushrooms are grown. After growers harvest mushrooms , the remaining material is made into compost. It’s a nutrient-rich material that improves soil structure, water retention, and nutrient content. It’s especially good for vegetables, flowers, and general garden use.

Geet a soil test done before adding any amendments, even organic amendments.

Benefits of Mushroom Compost

This particular blend is nutrient-rich. It includes nitrogen, phosphorus, and potassium, which are crucial for plant growth. These nutrients help vegetables develop strong roots, lush foliage, and abundant fruits.

We found out firsthand this year how rich it makes the soil. The past several years have seen a mediocre harvest for us in the raised bed vegetable garden. The only thing we changed this year is the addition of this special amendment. The results have been extraordinary. Over 20 cantaloupe from just two plants, bushel after bushel of tomatoes, and an abundant harvest of peppers.

Compost of any kind enhances soil texture, making it looser and more crumbly. This improves aeration and drainage, which helps prevent waterlogging and promotes healthy root development. It has good water-holding capacity, which helps maintain soil moisture and reduces the need for frequent watering. This is particularly beneficial during dry spells.

Frequently Asked Questions

What exactly is mushroom compost? Will it add mushrooms to my garden?

Mushroom compost is a type of organic material used as a soil amendment. It is the byproduct of growing mushrooms, typically composed of straw, hay, poultry or horse manure, gypsum, and other materials. After the mushrooms are harvested, the leftover compost is used to enrich garden soil, providing nutrients and improving soil structure.

How does mushroom compost benefit my garden?

Mushroom compost improves soil fertility by adding essential nutrients, including nitrogen, phosphorus, and potassium. It also enhances soil structure, increasing its ability to retain moisture and support root growth. Additionally, it can help with soil aeration and provide a habitat for beneficial microorganisms.

Can mushroom compost be used for all types of plants?

While it is generally beneficial for many plants, it is especially useful for vegetable gardens, flower beds, and lawns. However, because it is relatively high in nutrients, use it with caution for plants sensitive to high nutrient levels or those that prefer more acidic soils.

How should I apply it to my garden?

Apply this soil amendment in a few different ways: as a top dressing on the soil, mixed into garden beds, or used as a component in potting mixes. A common recommendation is to apply a layer of 1-2 inches of compost to the garden bed and gently work it into the top 6 inches of soil. For container plants, mix it with other soil components at a ratio of about 1 part mushroom compost to 3 parts soil.

Are there any downsides to using it?

One potential downside is that mushroom compost can be high in soluble salts, which may affect plants if used in excess or not well-composted. Additionally, it may have a higher pH level than some plants prefer, so it’s important to test your soil and adjust accordingly.

Will it add weeds? No. Most companies heat or steam treat the product, which kills weed seeds and prevents them from sprouting.

Where can I buy it?

Look for bags of mushroom soil or mushroom compost at home and garden centers. We purchased ours in bulk from a local provider of mulch.