Mushroom Compost

Mushroom compost is a peat-free, recycled soil improver made from composted agricultural straw and animal manures.

Use it to add organic matter and open up heavy clay, dug into beds, borders and veg plots or laid as a mulch, with a pH around 6.4 to 6.8. It is a soil improver rather than a compost to grow in directly, sold in 0.73m³ bulk bags, loose by the cubic metre, or by the kilogram, and delivered across the south of England.

What is mushroom compost, and what is in it?

Mushroom compost is a recycled by-product of mushroom growing, a blend of composted straw and animal manures that has already broken down into a dark, crumbly, earthy material. It is a soil improver: dug into the ground it adds organic matter, improves structure and water retention, and is especially good on high-clay soil. It also suits enriching planting beds for shrubs, flowers and vegetables. Because it is recycled rather than dug from the ground or milled from peat, it is an environmentally friendly choice that puts a farming by-product to good use. It is not made for sowing or potting into directly, so for seeds and containers use a growing compost instead.

Is mushroom compost good for clay soil?

Yes, it is one of the best improvers for clay. The bulky organic matter opens up the heavy, sticky structure of clay, letting air, water and roots move through it, so ground that sat wet and claggy works far more easily after a season. Fork a 50mm layer into the top of the soil in autumn, and on the worst clay add horticultural grit alongside it for extra drainage. This is much of why it draws steady local demand across Dorset's clay gardens, where opening the ground up is the difference between a bed that grows and one that waterlogs.

How to use it, and autumn spreading

Spread mushroom compost in a 50mm layer over the area and fork or rotovate it into the top of the soil. Autumn is the ideal time, as beds are cleared and put to rest, because the compost breaks down and works into the ground over winter ready for spring. On heavy clay, an autumn dig-in makes the ground far easier to work by spring. If you garden no-dig, lay the same 50mm as a surface mulch over cleared beds and let the worms pull it down, leaving the structure below undisturbed.

Where not to use mushroom compost

Do not use mushroom compost on acid-loving, ericaceous plants. Its pH sits around 6.4 to 6.8, near neutral, so it suits most vegetables, roses and general borders, but rhododendrons, camellias, azaleas and blueberries want an ericaceous compost instead. It is also a soil improver, not a growing medium, so keep it out of seed trays and pots, where a proper growing compost belongs. Used in the right place, on beds and clay rather than on acid-lovers and seedlings, it is one of the most useful improvers in the garden.

How much do you need?

A 0.73m³ bulk bag holds roughly 500kg and covers about 14 to 15m² spread at a 50mm improving depth. So a set of borders totalling 30m² takes about two bulk bags to improve at 50mm, and a single border takes under a bag. For larger jobs you can book loose loads up to 10m³ within our delivery area, and smaller amounts are available as refill bags and by the kilogram. Work out quantities with the calculator or the how much compost guide.

Mushroom compost in the vegetable garden

Mushroom compost is a strong choice for most of the veg plot, dug into beds in autumn to add organic matter and open heavy ground for the spring sowings. Its near-neutral pH suits the lime-liking brassicas such as cabbages, sprouts and kale especially well, and it improves how the whole plot holds water and works. The two things to keep in mind are to use it well ahead of sowing rather than fresh at planting, and to keep it off any acid-loving crops such as blueberries. Across a normal rotation of roots, brassicas, legumes and salads, an autumn dig-in of mushroom compost is one of the simplest ways to keep the ground in good heart.

Using mushroom compost as a mulch

As well as digging it in, you can lay mushroom compost as a 50mm surface mulch over cleared beds and borders in autumn and let the worms pull it down over winter. That suits no-dig beds and busy gardeners, because it improves the soil without the digging, holds moisture into spring and gives a fine surface to plant into. Keep the mulch off the crowns of perennials and the stems of shrubs, and top it up each autumn to keep the ground improving year on year.

A worked example

Mushroom compost versus horse manure

Choose mushroom compost to open up clay and add organic matter, and horse manure to feed hungry beds and roses. Mushroom compost works mainly on structure; horse manure carries more nitrogen, phosphorus and potassium, so it feeds as well as bulks. Many gardens use both, mushroom compost across the borders and manure on the veg and roses, which covers structure and fertility together. For the full comparison, see Bulk Compost Compared.

The other two bulk improvers

For fertility

Horse Compost

Well-rotted racing-stable manure, ready to use. The richer option where the ground needs feeding rather than opening up.

Order Horse Compost →

For compaction

Soil Structure Enhancer

Aimed squarely at compacted, lifeless ground rather than fertility. Worth a bag through the heaviest corner of a plot.

Get the Soil Structure Enhancer →

Delivery across the south and nationwide

Mushroom compost is delivered on Sherborne Turf's own vehicles across the south of England, with Dorset, Somerset, Devon, Hampshire and Wiltshire our key counties, and bagged orders go nationwide on a pallet line network, charged by postcode, with loose loads up to 10m³. Collection from The Lawn and Landscape Centre in Sherborne, DT9 4GH, avoids the delivery charge, which answers the “mushroom compost near me” search for buyers across the local area. See the delivery page for your postcode.

Mushroom compost FAQ