Mushroom compost is used as a soil conditioner and a mulch. High in organic matter, it enhances the structure of your soil and providing nutrients for healthy plants. It’s slightly alkaline, and should not be used with ericaceous plants, which thrive in acid soils.
Mushroom compost is an excellent organic soil amendment for gardens and lawns. It improves moisture retention, aerates soil, and adds beneficial organic matter But how much mushroom compost do you actually need to see results? Understanding proper application rates can help prevent waste and overuse.
This guide covers how to calculate the right amount of mushroom compost to buy and apply based on square footage. Read on for tips on measuring your area determining depth estimating cubic yards, and more.
Benefits of Using Mushroom Compost
Before getting into calculations, let’s review the key benefits mushroom compost offers gardens and lawns:
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Improves moisture retention and reduces watering needs
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Lightens and aerates heavy clay soils for better drainage
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Provides organic matter to help feed beneficial soil microbes
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Can be used as a nutrient-poor mulch option
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Breaks down slowly over 1-3 years to boost soil fertility
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Low-cost and renewable waste product from the mushroom industry
Mushroom compost is the leftover growing medium after mushrooms are harvested. It’s usually made from straw, manure, gypsum, and other organic materials. Using spent mushroom substrate recycles these waste streams into a useful soil amendment.
Determining Application Rates
You don’t want to use too little mushroom compost and miss out on the benefits But you also don’t want to over-apply, potentially causing drainage issues. Here are some guidelines on ideal depth and application rates
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Gardens: Apply 1-3 inches of mushroom compost and work into the top 6 inches of soil.
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Lawns: Apply 1/2 – 1 inch of mushroom compost as top-dressing.
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Potting mix: Blend mushroom compost at 25% or less of total volume.
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Planting holes: Mix 1 part mushroom compost to 2 parts soil backfill.
The best approach is to apply mushroom compost uniformly and evenly at a one to three inch thickness (three to nine cubic yards per 1000 square feet) on the surface of the intended site, and then incorporate into the existing soil below.
Measuring Square Footage
Before determining how many cubic yards of mushroom compost you need, you first need to calculate the square footage of the area you want to amend. Here are some tips:
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For rectangular areas, multiply length by width. Ex: 10 ft x 20 ft = 200 sq ft
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For circular areas, use the formula πr2. Ex: π(5 ft)2 = ~78 sq ft
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For irregular shapes, break into smaller rectangles/circles and calculate separately, then add together.
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Use a measuring tape to get accurate lengths and widths of the site, don’t estimate. Round up partial feet.
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Check square footage of bags/bulk loads so you know how much area they cover.
Measuring square footage accurately is a crucial first step towards buying the right quantity of mushroom compost for your needs.
Choosing Application Depth
The application depth depends on your specific goals:
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For minor soil amendments, apply 1 inch of mushroom compost
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To improve moisture retention, use 2-3 inches
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To lighten heavy clay soils, incorporate up to 3 inches
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For lawns, a 1/2 to 1 inch topdressing is ideal
If you incorporate mushroom compost too deeply (over 6 inches), the benefits will remain too far down in the soil profile to impact plant roots and growth. Aim to work it into just the top few inches where feeder roots are most active.
Estimating Cubic Yards Needed
Once you know your square footage and target application depth, you can estimate the cubic yards (CY) of mushroom compost required.
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First, convert your application depth into feet by dividing by 12 inches (ex: 3 inches / 12 inches per foot = 0.25 feet).
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Next, multiply this depth in feet by the square footage.
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Then divide the total by 27 to convert to cubic yards (there are 27 cubic feet per cubic yard).
For example, for a 3000 sq ft area with a 3 inch depth:
- 3 inches / 12 inches/foot = 0.25 feet
- 0.25 feet x 3000 sq ft = 750 cu ft
- 750 cu ft / 27 cu ft/CY = ~28 CY
So you would need approximately 28 CY of mushroom compost to apply a 3 inch layer over 3000 sq ft.
Use an online cubic yard calculator to easily convert square footage and depth into cubic yards.
Buying Bagged vs. Bulk Loads
Mushroom compost is sold bagged or in loose bulk loads:
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Bagged: Typically available in 1-2 cubic ft bags. Easy to transport and calculate amounts. More expensive per CY.
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Bulk loads: Sold by the cubic yard in dump trucks or trailers. Cheaper per CY but requires equipment to move. Arrange delivery or rent equipment.
For larger projects, bulk loads are the better value. But for small gardens, the convenience of bagged mushroom compost can be worth the added cost. Buy extra bags so you don’t run short on material.
Spreading and Incorporating Mushroom Compost
To make the most of your mushroom compost, proper application and incorporation techniques are key:
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Moisten mushroom compost before spreading if dry. This prevents dust and helps it spread.
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Use a shovel, rake or lawn spreader for even distribution. Focus on uniform depth across the area.
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For gardens, gently till or spade the mushroom compost into the top 6 inches of soil.
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For lawns, use a mulch rake to lightly work topdressed compost into grass.
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Level any mounded areas and re-spread if needed to get an even application.
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Water thoroughly after spreading to aid incorporation and settlement.
Taking the time to properly incorporate mushroom compost avoids waste and makes sure the entire garden or lawn benefits.
Alternatives to Purchasing By the Cubic Yard
If estimating cubic yards seems daunting, here are some simpler options:
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Buy mushroom compost by the bag and calculate how many you need to cover the area at the desired depth.
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Note the square footage covered by 1 CY in the product description and divide your total area by this figure to get the number of CY needed.
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Visit the supplier and ask for staff recommendations on how many CY loads for your project.
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For lawns, apply one bag per 200-500 sq ft as a rule of thumb depending on bag size.
Sometimes it’s easier to skip the math and use simpler guidelines based on bag quantities or coverage info. Record the actual number of cubic yards used for future reference.
Cost Factors
When budgeting for mushroom compost, consider these cost factors:
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Mushroom compost prices range from $15 – $55 per cubic yard.
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Bulk loads are cheaper per CY than bagged products.
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Delivery fees can add $50 – $150+ for bulk loads.
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Equipment rental for spreading will add hourly/daily costs.
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Labor for spreading and incorporating will increase costs for large projects.
To get an accurate estimate, obtainquotes from multiple mushroom compost suppliers in your area and compare based on total project cost.
Estimating Application Frequency
While mushroom compost lasts 1-3 years before reapplying, the actual breakdown rate depends on climate and composition:
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Hot, humid climates speed decomposition so compost has to be reapplied more frequently.
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Products with more woody materials like straw or sawdust break down slower.
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Finer, manure-based composts decompose faster and have to be reapplied sooner.
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Heavy rainfall can leach nutrients, requiring more frequent applications.
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Incorporation speeds the breakdown process compared to topdressing.
To determine your own site-specific application frequency, monitor how quickly each batch of mushroom compost depletes each year in your conditions. Adjust the reapplication schedule accordingly.
Signs It’s Time to Reapply
Watch for these signs it’s time to replenish the mushroom compost layer:
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Soil moisture retention decreases.
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Soil compaction and poor drainage return.
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Plants show less vigorous growth.
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Mushroom compost layer is no longer visible.
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Bad odors from anaerobic conditions.
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Grass thinning or bare patches reappearing.
Don’t wait until all the benefits disappear before reapplying mushroom compost. Staying on a regular schedule based on observed decomposition rate is ideal.
Common Application Mistakes
Some common mistakes lead to wasted product and money when applying mushroom compost:
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Not accurately measuring the square footage and buying too little.
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Applying too thin a layer to provide meaningful benefits.
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Using pure mushroom compost instea
When to use mushroom compost
Spread a 5 cm thick layer of mushroom compost over the soil’s surface in the spring to use as mulch and to improve the soil’s health. If spreading it on vegetable beds, leave for a week after application before sowing seeds.
Why should you use mushroom compost?
You can make your soil better by adding mushroom compost. This will give plants the air, water, and nutrients they need to grow well.
Mushroom compost has a lot of organic matter, which makes all types of soil better, from heavy clay to light sand that drains easily. Organic matter makes the structure and air flow of soil better while also making it better at holding water and draining. Traditionally, manure or compost would be incorporated into soils through single- or double-digging. More recent “no-dig” methods suggest leaving the soil’s structure alone and covering the flower or vegetable bed with a thick layer of compost. Then, soil organisms like worms, beetles, and millipedes should slowly work the compost into the soil.
Mushroom compost also provides the nutrients that plants need to grow well. The three most important nutrients for plants in soil are nitrogen, phosphorus, and potassium. Magnesium, calcium, and sulfur are also very important. These nutrients work together to help plants grow strongly and produce flowers and fruit. They are particularly important on the vegetable patch as vegetable crops need a lot of nutrients. Plant roots can get nutrients from dead plants, manure, and other organic matter that is broken down by invertebrates, bacteria, and fungi in the soil. Mushroom compost is slightly alkaline, with a pH of 6. 5-7, which is suitable for a wide range of ornamental plants. It’s also good for many kinds of vegetables, like brassicas (which are related to cabbage) because the higher pH protects against club root and tomatoes because the higher calcium levels protect against blossom end rot.
Mushroom compost might have less nitrogen than other composts because the mushrooms that were grown on it used up all the nitrogen. Lower nitrogen levels, on the other hand, will encourage the growth of flowers and fruit, while high nitrogen levels can tell the plant to focus on making leaves.
Is Mushroom Compost Good For A Garden Or Should You Avoid It?
FAQ
How much mushroom compost should I add to my garden?
Can you use too much mushroom compost?
How much does 1 yard of compost cover?
What plants don’t like mushroom compost?
How much compost do you need for a mushroom garden?
The best approach would be to apply mushroom compost uniformly and evenly at a one to three inch thickness (three to nine cubic yards per 1,000 square feet) on the surface of the intended site, and then incorporate into the existing soil below. Next, seed or transplant the desired vegetation.
How do you use mushroom compost?
It is best applied to garden soil in early spring or long into summer for vegetable gardening. When amending garden soil, spread the compost evenly and till it 1-3 inches into the top 6 inches of soil. For container plants, it’s best to mix in ¼ mushroom compost with ¾ of your potting soil mix.
What is the pH level of mushroom compost?
Mushroom compost pH levels are around 6.6, putting it in the neutral range. Blended into soil, mushroom compost provides a readily-available source of organic material, which retains water and help to amend clay-like soils over time. However, mushroom compost shouldn’t be used to replace your standard compost.
Is mushroom compost good for soil?
It’s true that mushroom compost can be good for your soil – but there are caveats. Ultimately, the impact of this compost depends on different factors. These include soil, the plants you are growing, and the quantity you add to your soil. So before you rush out and start using mushroom compost on your soil, let’s take a detailed look at it.
When should you mix mushroom compost?
Mushroom compost does its best work when it sits in the soil for a while before planting season. To accomplish this, you should mix mushroom compost thoroughly into the soil in autumn and let it sit over the winter. This way, the nutrients have time to seep into the soil so that they can provide as much benefit to your plants as possible.
Should I Topdress my soil with mushroom compost?
Topdressing your soil with mushroom compost prevents its direct exposure to the elements, which often leads to soil compaction. Instead, the soil becomes more aerated and much easier to work on while also supporting proper root development. Considerations When Buying