In recent years, mushroom compost has become a popular choice amongst gardeners for many reasons; from its high nitrogen content to its ability to transform nitrogen-lacking soils.
In this blog, we’ll discuss everything you need to know about spent mushroom compost from how it’s made and how it will transform your gardening.
What is spent mushroom compost?
Spent mushroom compost is a by-product of the mushroom growing process and is comprised of horse manure, poultry manure and wheat straw. With a pH scale of around 6.6,
Spent mushroom compost is great for many things, including improved soil structure, weed reduction and moisture retention. It can also be used to support the growth of various plants, fruits and vegetables, but should be done only when mixed with two parts soil to one part mushroom compost.
As it contains 30% more chalk, its higher alkalinity and nitrogen content can cause a waterlog if not mixed.
Why should I use spent mushroom compost?
Spent mushroom compost is used by gardeners and landscapers alike looking to improve the quality of their soil. Used either for amending acid soils or to enhance plant growth. It should be mixed with two parts soil and one part spent mushroom compost. to grow plant life.
There are many benefits of applying mushroom compost to your soil including:
- Soil structure and aeration: Similar to regular compost and organic mulches, spent mushroom compost helps create a good soil structure helping with water infiltration, soil aeration and nutrient availability.
- Breaks up heavy soil: Organic matter and high nitrogen content help to break up heavy soil and loosen compact clay particles.
- Boosts soil drainage: The organic matter creates pore spaces in the soil structure allowing excess water to drain easier.
- Reduces weed growth: When applied as a layer of mulch, it suppresses weed growth by blocking sunlight from entering.
- Retains moisture: With good water-holding capacity, it does well to retain moisture in the soil, ensuring plenty of hydration to plant life.
- Contains essential nutrients: With high levels of phosphate, potassium, calcium and magnesium, it contains key nutrients that will enhance soil quality and promote root growth.
- Easy to apply: Simply mix two parts soil to one part mushroom compost, add to the top of your soil to a thickness of around 50mm and work it into the soil.
How can I use spent mushroom compost?
As a soil improver: Spent mushroom compost contains a high nitrogen and chalk content rich in calcium and magnesium, which creates liming to increase the soil’s pH level. By simply applying to a 50mm thickness and working into the soil or leaving it as a mulch, you can breathe life back into heavy clay soils.
Growing vegetables: It can also be used for growing a wide range of plants including root vegetables, brassica vegetables and rose bushes – all of which thrive in loosened soil.
What can I grow in spent mushroom compost?
- Root vegetables such as onions, potatoes, carrots & garlic
- Leafy greens & brassica vegetables such as lettuce, spinach, broccoli & kale
- Fruit vegetables such as tomatoes, peppers & squash
- Herbs such as basil, coriander, parsley, rosemary & oregano
- Flowers such as roses, sunflowers, marigolds, petunias, dahlias & daylilies.
Are there any downsides to using spent mushroom compost?
Whilst it’s a great choice for improving your soil’s quality and growing vegetables, there are some things you should keep in mind when using it.
Due to the high alkalinity, If the soil is already highly alkaline, the use of spent mushroom compost can make other nutrients in the soil less available.
Also, make sure not to overdo it! It contains a high salt content, making it hard for plant life to thrive independently. To avoid this from happening, it should be with two parts soil and one part mushroom compost – especially when growing vegetables.
What Should I Avoid Growing In Spent Mushroom Compost?
While spent mushroom compost is great for many plants, there are some instances where it can cause more harm than good.
- Acid-loving plants: The higher alkalinity of mushroom compost can create a toxic environment for ericaceous plants that grow in acidic soils such as rhododendrons, camellias, azaleas, heathers, blueberries, cranberries & hydrangea. When growing these succulents, it’s best to use compost with a low pH such as leaf mould.
- Shallow-rooted plants: Mushroom compost is typically loose and lightweight, which makes it less viable for shallow-rooted plants like aloe vera or strawberries, which need compact soil to stay standing.
- Salt-sensitive plants: Some mushroom composts contain a high concentration of sodium which make the soil a toxic environment for ferns or orchids.
- Mushrooms: Spent mushroom compost is the by-product of previous mushroom growing and therefore cannot be used again for growing mushrooms.
Where to buy spent mushroom compost?
If you’re looking for a versatile soil amendment, mushroom compost is a great option. At Envar, we offer 100% British Spent Mushroom Compost in 900-litre bulk bags that can be used for a variety of gardens. This compost is steam-sterilised during the cultivation process, making it an excellent choice for improving soil health.