Tough or tender?
In the table below, ingredients marked as tender (1) will start the composting process. They are nitrogen-rich and decompose quickly but provide little fibre to give the compost body. Too much will result in a soggy, smelly heap. Those marked as intermediate (2) will not decay as quickly as tender materials but will provide structure to the compost, and those marked as tough (3) will provide structure for the compost but will decompose very slowly unless mixed with more tender material. Living materials are variable, so these classifications should be taken as guidelines only. Plants get tougher as they age.
The average house and garden can produce a fair amount for the compost heap but if you are a keen gardener this will never be enough. Further supplies include straw, hay, vegetable scraps from the greengrocer, weeds and mowings from non-composting neighbours, pigeon manure from local lofts and stable manure. Materials to avoid are grass or straw recently treated with weedkiller, anything carrying a persistent weed, pest or disease, and manures from intensive farms.
Pests and diseases
The compost heap is often thought of as a breeding ground for pests and diseases, but this is often not the case. A hot heap kills off all but the very persistent diseases like clubroot, and even in a cool heap the intense microbial activity can dispose of disease organisms.
As a general rule, diseases that only survive on living plant material can be composted. Those that survive in dead and decaying plant material are best omitted from a slow, cool heap. Diseases that produce resistant restingshould be avoided altogether.
You may find a few pests, such as slugs and wireworm, in a maturing compost heap as they are part of nature’s army of decomposers. Do not worry; the compost heap will not cause a population explosion in your garden. Never use a pesticide on a compost heap.
A compost activator initiates the whole process of composting. Natural activators include grass mowings, young nettles, comfrey leaves, urine and poultry manures. If one (or more) of these is used, there should be no need to add a purchased activator. If you purchase an activator, choose one based onor bacteria; avoid nitrogen fertilizers.
Bedding and manure from pets such as rabbits, guinea pigs and gerbils can be added to a compost heap. Treat cat and dog manures with caution as they can contain organisms that are harmful to humans; if these manures are to be composted, they should be added to a good mixed heap that will heat up. The resulting compost should be handled with care, and used on ornamentals only.
The composting of cat and dog manures is not advised where children have access to the compost, either in the heap or on the garden.
|Bracken||2||3||Cut when green; do not collet when producing.|
|Comfrey leaves||1||See Comfrey Uses|
|(old plants)||3||Chop into small pieces with a sharp spade; do not add clubroot-infected roots.|
|Diseased material||–||–||–||See Plant Diseases|
|Food scraps||1||2||Mix well with other ingredients; if scraps only are available, consider a worm compost system.|
|Feathers||1||Mix well with other ingredients; 15% nitrogen.|
|Glass||Will not compost.|
|Grass mowings, young||1||Do not use if weedkiller has been used within the last two mowings.|
|Grass mowings, long rough grass||2||Water well before adding if dry.|
|Hay||2||A good source of plant foods; soak well before adding if dry.|
|Hedge clippings||See prunings (below)|
|Manure with straw bedding (see also poultry manure)||2||Usually cow or horse. Composition will vary. Can act as an activator if fresh and the straw is well soaked with urine.|
|Manure with shavings||3||Usually horse, use with caution: see Types of Organic Matter for more details.|
|Manure, pet||May be used, but with caution, see above.|
|Manure, poultry, no bedding||1||Very nitrogen rich; do not obtain from intensive farms.|
|Manure, poultry, with bedding||2||Will also act as an activator if there is a high proportion of manure to straw. Straw and poultry manure together will make good compost.|
|Metal||Will not compost.|
|Nettles, old||2||A patch of nettles can be cut for composting twice a year.|
|Nettles, young||1||See nettles, old (above)|
|Plant and Crop residues||2||3||See diseased plant material|
|Paper||Of little value in a compost heap; will soak up excess moisture. Tear up before use. Avoid coloured inks in any quantity.|
|Plastic||Will not compost.|
|Potato haulm||2||Blight-infected haulm can be composts; infected tubers should not be added to a compost heap.|
|Prunings, soft green||2||These can be added directly to the heap.|
|Prunings, woody||3||Chop small or shred before ading to a mixed nitrogen-rich heap. See Tips on Garden Shredding. May have to go through a heap several times. Large quantities are best made into a separate heap.|
|Rhubarb leaves||2||Although poisonous to eat, these can be safely composted.|
|Sawdust||3||Small quantities may be added to a heap.|
|Seaweed||1||Fresh seaweed may be collected from the beach. See Types of Organic Matter for more details. Encourages bacterial action; adds trace elements.|
|Straw||3||Useful for bulking up soggy heaps. Old or chopped straw is best. Soak first if dry.|
|Urine, human||1||Rich in nitrogen and potassium; dilute with around 3 parts water and water on to the heap.|
|Weeds, annual||1||2||Weed seeds may not be killed in a cool heap.|
|Weeds, perennial||2||contain a lot of goodness so compost if possible. Kill them first by leaving in the sun to dry or make a separate heap which is left to compost for a longer period. Do not compost oxalis or celandine.|