The qualities of Mushroom Compost

As Used by Monty Don follow the link to his article in the guardian gardening section.

What is it?

The mushroom compost is low in soluble nitrogen, which means there is little risk of plant burn, the total nitrogen is present in such a form that it will be released over time as further decomposition takes place.  Phosphate, potassium. calcium and magnesium levels are quite high.  Salinity is well below the levels found in conventional manure, the micro element analysis is good for copper, high for zinc manganese and iron and slightly low for boron.

Composition of spent mushroom compost:

Nitrogen 22.5
Iron 2153
Phosphorous 12.5
Manganese 376
Potassium 25.0
Boron 37
Calcium 72.5
Copper 46
Magnesium 6.7
Zinc 273
Sulphur 15.9
Sodium 2.7



Mulching.  This means spreading mushroom compost onto the surface of the soil, there is no need to dig it in.  As a fertilising mulch it maintains the soil and increases the nutrients.  It will improve the soil structure and helps make existing soil food more readily available to plants  Mulching helps retain moisture in the soil and most importantly reduces the number of weeds which grow. SO YOU DON’T HAVE TO DO MUCH WEEDING!





Mushroom Compost Growing Tips

How much does it cost?

  • 3 cubic meters  delivered from  £102 inc VAT ( depending on area)
  • 1 bag  (collected from the farm) £3.00
  • 4 bags (collected from the farm) £12.00 

Soil conditioning

If you have very heavy clay soil, or one which has been compacted mushroom compost is an ideal soil conditioner.  If the compost is spread on the surface and is then dug into the soil it will lighten and help to aerate the soil.  The soil will take on a crumbly texture.  The soil is subsequently easy to work.

Compost should then be incorporated on an annual basis to maintain this structure.

Mushroom compost should not be used on acid loving plants as at is slightly alkaline.

On the vegetable patch apply to crops that like a richer soil such as cabbages, courgettes, potatoes, tomatoes & pumpkins.

Mushroom compost is best applied in the spring before planting, so that the growing plants can get the best from it.  It is also useful as a mulch on brassicas for a mid season fertility boost, this includes growing trees and those on dwarf rootstocks.

In the fruit garden, Mulch blackcurrants annually as they are greedy feeders.  Mulch strawberries every year if they are on poorer soils. On container plants Apply once a year to the surface of the pot.