How organic matter is used for
garden composting

PAGE CONTENTS:

Sources of material for garden composting
Composting turns readily available organic materials into valueable plant food and soil conditioner for the garden. The advice below explains how to obtain that important mix of 'greens' and 'browns' and how to treat a variety of recyclable materials.

You can find more on how to use compost bins on these links:
tumbler compost bins
continuous compost bins and
larger slatted timber bins plus
my explanatory notes on composting basics.

You can recycle most organic materials one way or another. Organic matter is best thought of as 'material derived directly or indirectly from living things'. It includes garden and kitchen waste as well as some household materials like cardboard, paper, old carpet...

Distinguish between:-

  • GREEN SAPPY MATERIAL, ('Green' & relatively higher Nitrogen content, good for hot rapid composting) and
  • DRY FIBROUS MATERIAL, ('Brown' & relatively higher in Carbon content, excess cools and slows garden composting);
both are usually needed to provide nutritional balance for microorganisms (C/N ratio = 25 to 30), and to control moisture content. It's best to chop or shred organic matter before adding to heap.

Please note that your local government regulations may prohibit garden composting of certain materials. Find a suitable treatment for your organic waste below. It deals with the main organic sources under the headings:
Garden Plant Waste, Green Manure, Kitchen Waste, Household Waste, Animal Manure, Other sources, Commercial sources, and Not For Recycling Or Composting. There may be a community compost garden in your area. Don't forget, the alternative to garden composting is more expense on fertilizers and soil conditioners as well as on waste disposal.

G A R D E N   W A S T E

GRASS LAWN CUTTINGS
Use lawn cuttings on the heap: A readily available source of material for garden composting. They should be stirred for aeration during composting. Mix with browns such as dry leaves, prunings, & sawdust.
Don't compost from lawns recently treated with selective weedkillers.

Use lawn cuttings as a mulch: Spread around shruberies, but not in thick layers or over surface feeding roots (e.g. small fruit, rhododendrons). Grass cuttings feed worms and plants, keeps the soil moist, and inhibit weeds.
!! Lawn mowers are now available that finely shred grass cuttings and inject them directly back into the lawn. This facility can be turned off for normal grass collection.

AUTUMN / FALL LEAVES
Use leaves on the heap: Leaves pile up in the fall. Don't burn them. Rake up and store in bags for mixing with 'Green' organic matter later. Shredding them before composting will help.
Wet leaves may compact into layers that effectively exclude oxygen, in this condition they must be regularly stirred and aerated. Rather than add them altogether it is better to store and mix with grass cuttings, weeds, and kitchen waste.

Autumn leaves are not recomended for the worm bin: as leaves that accumulate in piles over soil often contain a myriad of creatures. These will be transferred to your worm bin. So although layers of damp leaves with the worms seems a good idea, in fact I don't recommend this for small worm bins.

WEEDS - Mixed C/N ratio
Use weeds on the heap: It is possible to compost weeds provided you take certain precautions.
Do remove weeds for composting before seed heads appear and preferably before they flower.
Do dry weeds out in the sun before composting if they are perennial weeds with underground roots or stems.
Don't compost tough pernicious weeds like Horsetail that spreads by tiny bulbils growing at stem junctions. Better to burn these.
Do ensure that the compost reaches a high temperature of about 60oC, 140oF, and that it is stirred to ensure that weed seeds spend time in the hot spot.
Don't recycle weed seed or living perennial weeds back into your soil through your garden compost.
A slow cold compost heap is less likely to kill weed seed by heat, but hopefully viable seed will then germinate inside the heap at some point and be destroyed mechanically. Mix the heap regularly.
Don't add deseased weeds - see diseased plants below.

DISEASED PLANTS
Don't add diseased plants (e.g. with fungus infections such as rust, botrytis, scab, etc) to the heap. These should be burned.

VEGETABLE TRIMMINGS WASTE
THINNINGS
END OF SEASON PLANTS
DEAD OLD PLANTS
Put them all on the garden compost heap: Fresh vegetables especially Legumes, and Brassicas, can be higher in nitrogen (lower C/N ratio) but older tougher plants will have more carbon. Dead flower stalks and flower heads will be higher in carbon - [see note on diseased plants] [see spent compost] -

POTATO TUBERS C / N ratio=18
Can go onto the heap: For you to consider composting tubers at home they're most likely to be already damaged, or too small for use. Don't compost diseased potato tubers. Don't allow tubers to sprout; keep them covered in the dark.
First chop and crush them by stamping on them, or shred them. The pulp can be added to the heap.
Growths produced by tubers under cover in the dark of a bin will be long, leggy, and weak. Any plants that do grow can easily be stopped by chopping. Just be sure to compost thoroughly at a high temperature so viable plant growths are not passed out with finished compost. If composting large amounts of cull potatoes then it's probably best not to use the compost on land that will grow potatoes within the next 2 years.

Feed to animals:

HEDGE TRIMMINGS
PRUNINGS
Shred and put on the heap: Chop as finely as possible first to expose the wood to microbial attack. This is best done with a shredder. Small green and woody branches of Privet, Beech, Hawthorn, Holly, Berberis, Cotoneaster, Leylandii - you name it, they're all easily composted after shredding. They add carbon and fibre to mix in with high nitrogen matter like horse and poultry manures, and grass cuttings. The artisan of the garden composting will find ways to both recycle and balance organic matter.

BARK
Use as a mulch or put on the wood pile: - see below.
WOOD
CHIPPED AND LARGER SHREDDED BRANCHES
Add to a wood pile: Wood has a high carbon/nitrogen ratio. It composts too slowly for the compost heap, but the compost gardener includes other methods.
Add chipped wood (of branches larger than 1cm diam) to a Wood Pile and keep this pile in the dark and covered to protect from rain water. The wood will become populated by Wood Lice and other organisms that eat and digest the wood. Over time, say 3 years, it will be turned into insect droppings, or mull. This is black of a fine consistancy and lovely earthy smell as if straight from the forest floor. You may need precautions to prevent the Wood Lice spreading to other areas. But when these small animals do venture out they provide food for birds, and other animals. I haven't chemically tested the product but I expect it to be considerably higher in nitrogen than the wood you start with.

ROTTING WOOD, OLD POSTS, FENCES...
Add to a wood pile: If you have any old wood with signs of rot even from window frames, or doors, as well as logs, then add to a wood pile and allow to rot. Wood treated with paint or preservatives may slow the process by preventing fungal attack. But material that already shows signs of decay, (e.g. softness, water soaked, flaking) is open to complete decomposition.

SPENT POTTING COMPOST
Add to compost heap: Return both peat based and soil based spent compost to the compost heap along with any root balls. It may contain microbes useful in decompostion as well as unused fertilizer. Nutrients released from decomposing organic matter will be adsorbed onto this old compost helping to prevent nutrient losses. The grit in old compost helps the worms digest organic matter. It may help in ventilating the heap and be useful in improving the drainage and feel of the final consistency. Large amounts will tend to cool the heap. With a cool slow heap you would use it in a layer between the green stuff.

SPENT MUSHROOM COMPOST
Add to garden compost bin: Rich in nutrient content. Helps your compost to heat up. Usually free of contaminants. Too concentrated for direct application to new plants or seed beds.

POND SLUDGE
Add to compost heap in thin layers after drying: This can be smelly but it should be recycled as it contains nutrients. These include fish droppings and other animal droppings, excess fish food, dead animals, decaying leaves, as well as midge and mosquito larva and lots of silty sediment. Smell is the main problem with pond sludge, so take care with neighbours and local government regulations. That said the smell should dissappear quickly when the material is exposed to the air and dried. After drying it out, I favour adding it to the compost heap. If you have a lot of pond sludge then it could be added to an open heap in thin layers a bit at a time. Layers should be dry on top of the heap before being covered or worked in.
Also, try adding thin layers of dried pond sludge to a worm composter.
Don't add dead invertebrate animals, e.g. dead fish, birds, vermin... to any domestic composter.

compost gardening main catagories

K I T C H E N   W A S T E

UNCOOKED VEGETABLE WASTE
VEGETABLE TRIMMINGS
Including: greens, stalks, pods,
Add to compost heap: High nitrogen content for good fertilizer - green stalks.
Add to worm bin: Softer green waste - pea pods, peel, leaves...

LETTUCE LEAVES
Add to worm bin: Worms can more easily cope with softer plant matter.

POTATO PEELINGS
Add to worm bin: One worm bin probably won't be enough to take potato peelings every day; the excess goes to garden composting.
Add to compost heap: Thin delicate potato plants may grow from peel but don't worry, they are not strong enough to withstand continuous dark or the disturbance and turning of the heap.

ONION PEEL
Add to the garden compost heap:
Don't add to worm bin: Too acid for good worm composting.

COOKED VEGETABLE WASTE
DINNER WASTE
e.g. left over cooked potatoes, chips, rice, spagetthi, greens, cake, bread,
Add to the Worm Composter: Worm bins may be better protected from vermin than your open garden compost heap. As worms won't cope with hard raw material without some initial decompostion, the waste from cooked material is a good choice for putting in the worm bin.

Add to Garden Composter: High nitrogen content is useful. Mix with paper kitchen towels, newspaper, tissue paper.

Don't recycle cooked or uncooked meat, cooked or uncooked dairy products (except egg shell) in domestic units. These materials don't contain cellulose and have higher nitrogen content. They usually smell bad and attract vermin and flies. If that doesn't put you off then do check your local government regulations and be sensitive to neighbours.

DAIRY PRODUCTS except eggshell
Don't add to compost heap or worm bin.

EGG SHELL
Crush and add to the Worm Composter: Real good for worm composting.

FRUIT
Add to worm bin: banana skins
Add to compost heap: apple cores, melon skin, citrus peel - if you add these to a worm bin then I recommend that you do chop them up - it's a good thing to do before any type of composting.
Leave small portions on bird table: early morning and early afternoon. Birds benefit from high protein foods in spring and summer.

NUTS
Leave out for birds: especially in autumn and winter when higher energy foods are required. Birds may not eat stale nuts... Place on bird table out of reach of other animals... Don't feed salted peanuts to birds... Some types of peanuts are high in aflotoxin...
Add to garden compost: the bird food option is also useful if your heap is frozen in winter.
NOT suitable for worm bin:

TEA BAGS C/N ratio=70
TEA LEAVES
COFFEE GRINDINGS C/N ratio=20
Add to worm bin: A good meal for worms.
Add to garden composter: if you don't have a worm composter.

CEREAL FLOUR FROM THE BOTTOM OF CEREAL PACKETS
Add to worm bin: A good meal for worms.
Put on bird table: especially in autumn and winter. Different birds have a different food preferences.
Add to garden composter: if you don't have a worm composter. Remember - waste not, want not.

PAPER KITCHEN TOWELS
GREASED PAPER CAKE DISHES
PAPER BAGS
Add to worm bin:

THIN CARDBOARD DINNER TRAYS & PACKAGING
Add to garden compost: Shred or tear up first.

compost gardening main catagories

D O M E S T I C   W A S T E

NEWSPAPER
Add to worm bin: Makes a good blanket to cover the waste. Worms can hide in the warm and dark underneath - they won't be disturbed when you lift the lid. Don't completely seal over the top with moist paper - worms may suffocate. Shredding the paper speeds its decomposition.

Use your local used paper collection and recycling service to recycle the bulk of your paper waste: Commercial plants have been set up in many areas to remove the inks from paper and recover clean paper pulp for the paper mill. Managed quantities of waste from this process are used on fields in agriculture without problem.

Add to garden compost bin: Feed in smaller amounts of excess paper waste into your compost. High C/N ratio of paper helps balance material with low C/N ratio such as grass cuttings. Don't dig paper into the soil as microbes will remove available nitrogen to decompose it.

Don't recycle masses of printed paper through the compost heap and avoid heavily inked pages. The inks in paper contain lead, cadmium, zinc... etc .

WASTE PAPER
Add to worm bin: Tear up first. More expensive robust papers have calcium carbonate and clay fillers added to the fibres. This should be good for the worms.

THIN CARDBOARD
Add to garden composter: tear up first.

CARDBOARD TUBES OF LOO ROLL / TOILET ROLLS ETC...
Straight onto garden composter: no need to tear, they are useful in providing air pockets within the heap.

Make pots for seedlings: fill cardboard roll with compost and sow seeds of e.g. sweet corn, courgettes, beans, tomatoes; most plants that are to be transplanted outside. The pots break down in the soil.

VACUUM CLEANER DUST
WASHING MACHINE FILTER
CLOTHES DRIER FILTER
Includes fluff, fabric, wool, fibres, pet hair, powder, grit...
Add to worm bin:

PET DIRT AND DROPPINGS
Don't add to compost heap or worm bin.

PET STRAW BEDDING
Add to compost heap or :
Add to worm bin:
Put out for birds in late winter and spring: for nesting material.

OLD CLOTHES
Wool, Cotton, Linen.
Add to worm bin: Wool makes an excellent cover that worms enjoy. Cut fabric to size and place in a layer.
Add to compost heap if you don't have a worm bin:

OLD CARPET
Add to compost heap: Makes an excellent cover for an open compost heap.
Put out torn up pieces for birds: to use as nesting material in late winter and spring.

OLD ROPE AND STRING made of natural fibres.
Add to compost heap: No nylon.
Put out small pieces for birds: to use as nesting material in late winter and spring. TAKE CARE that the birds don't get entangled and trapped.

main catagories

G R E E N   M A N U R E S

ALFALFA, BUCKWHEAT, PHACELIA, CLOVERS, FENUGREEK, AND OTHERS...
Add to garden composting bin: Green manures are usually cut down and dug in. Young plants are most valuable for this treatment as they are high in nitrogen. Older plants have higher carbon content and their breakdown in the soil will therefore remove available nitrogen from the soil. But you can also rake up the harvest and compost it. You can do garden composting with lots of high carbon waste by purposely growing a high nitrogen crop to mix with it.

If you plan to sow seed soon after digging in a green manure, then be aware that these plants release germination inhibitors. The inhibitors are better broken down with the garden compost.

click for MUSHROOM COMPOST WASTE

main catagories

A N I M A L   M A N U R E S

see my page on farmyard manure here

POULTRY MANURE C/N ratio = 10+
Be aware that this can increase salt content and direct application to beds may damage plants.
Add to garden compost bin: Very high nitrogen content helps to make a hot heap. Mix with saw dust; shredded paper, cardboard, hedge trimmings. It may contain weed seeds.

HORSE MANURE C/N ratio = 25
Add to garden compost bin: Exellent for hot composting.

Worm bin??: May contain worm killing medication.

COW MANURE C/N ratio = 13
Add to garden compost bin: Often wet and lowers the achievable composting temperature - allow to dry first. Be aware that too much could increase salt content.

PIG MANURE C/N ratio = 13
Add to garden compost bin: Often wet and lowers the achievable composting temperature - allow to dry first. Be aware that too much could increase salt content.

main catagories

M A T E R I A L   N O T  F O R   C O M P O S T I N G

SOFT PLASTIC BAGS
HARD PLASTIC
POLYSTERINE INSULATION ETC...
'MAN MADE' FIBRES
FOAM
METAL
PET DROPPINGS
DEAD VERTEBRATE ANIMALS
UNCOOKED MEATS
COOKED MEATS
DIARY PRODUCTS Except Egg Shell

The Bottom Of The Garden - More About Garden Composting Below

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