Green Cone fact sheet

Unlike a composter, a Green Cone has been specially designed to digest cooked and processed food waste.

In a Green Cone, 90% of the food waste is converted into water which is absorbed by the soil. The remainder is converted to carbon dioxide and a small amount of residue, meaning that a well operating Green Cone will only have to be emptied or moved every few years.

The Green Cone consists of a double walled solar cone and a digestion chamber. The double walled cone creates a heat trap for circulating air to encourage friendly micro-organisms to multiply and for this reason it is essential that the Green Cone is placed in a sunny position. The digestion chamber is dug into the ground and requires well drained soil to ensure aerobic conditions for the micro-organisms and worms which will migrate in and out of the digestion chamber and break down the waste. If you do not have well drained soil or live in an area of heavy clay or chalk you will have to dig a larger hole and back fill it with an mixture of gravel, stones, broken terracotta pots and broken bricks to ensure good drainage.

Getting started

  1. Choose a sunny position in the garden, preferably on well drained soil.
  2. Dig a hole 80cm wide by 60cm deep. If your soil isn’t free draining (for example clay soil) dig a larger hole 90cm wide by 70cm deep to allow improved drainage.
  3. Mix some of the soil from the hole with gravel and use for back filling to improve drainage. In areas of poor drainage (such as clay soil) add stones, pieces of brick and broken terracotta pots to the backfill mixture.
  4. Put some of the backfill mixture in the base of the hole followed by the digestion chamber so that it is 3cm below ground level. Place the assembled double walled cone on top of the digestion chamber ensuring that the top of the black digestion chamber and the bottom lip of the green outer cone are below ground level.
  5. Backfill the hole until the bottom lip of the green cone is fully covered.
  6. Begin adding food waste. Cooked and uncooked food waste can be added including: meat, fish, bones, dairy products, vegetable and fruit peeling. Add cooking oils and fats. Add hard shells of nuts and seafoods such as crabs and oysters in moderation as these can take a long time to break down. Animal excrement can also be added.
  7. The Green Cone is supplied with a small caddy that can be used in your kitchen to collect food waste prior to putting it in the Green Cone. The lid of the caddy contains a filter to reduce food waste odours in your kitchen.
  8. Your Green Cone is also supplied with an accelerator powder. The powder is a mixture of bacteria on a cereal base that ensures a healthy population of safe, friendly bacteria in your Green Cone. The accelerator can be used during the first week after installation or when there are long periods of cold weather etc.

Common questions

Where should I put my Green Cone?

Place it in a sunny, well drained position in your garden. Do not put your Green Cone in a cold, dark, wet place as it will not work properly.

What can I put into my Green Cone?

You can add fish, meat and poultry, bones, bread, dairy produce, cooked food scraps and animal excrement.

How much food waste can I put in my Green Cone?

Three quarters to one kilogram of food waste can be disposed of in your Green Cone each day. This is a typical amount produced by a family of four. The precise quantity of waste digested by your Green Cone each day will depend upon the ambient temperature, the population of bacteria and the mix of waste you produce.

What about methane?

Food decomposing in the presence of oxygen in your Green Cone produces very little methane.

Can I use chemical activators?

No. Chemicals can kill or disrupt the bacteria breaking down the food waste.

Can I use my Green Cone to dispose of animal excrement?

Yes, in moderation. Make sure you wear gloves and wash your hands afterwards.

Can I put garden waste into my Green Cone?

It is better not to. A traditional compost bin or heap is better at handling this type of waste. It is also better to use your compost bin or heap to deal with uncooked fruit and vegetable peelings, tea bags, coffee grounds and egg shells too.

Do I have to turn or mix the contents of my Green Cone?

No, just add your food waste into the cone.

Will my Green Cone work all year round?

Yes, your Green Cone works 365 days a year. The level of food waste may rise during winter but should decrease when the weather gets warmer. If it slows during very cold periods, add the natural Green Cone accelerator powder provided.

Can my Green Cone stop working?

Problems may occur if the advice on locating your Green Cone given in this booklet is not followed, namely:

  • it must be in a sunny spot in your garden and not a shady area
  • the surrounding soil must be well drained and not heavy clay or chalk
  • the black basket must not be below the water table or in an area where water gathers

If these instructions are not followed the digestion process could turn anaerobic (without oxygen) and the food waste will appear wet and slimy. The only solution is to reinstall your Green Cone in accordance with these instructions.

In periods of cold weather the digestion process may slow down due to lack of natural bacteria. This would be evident by the level of waste in the basket not decreasing. Under these circumstances the addition of the natural Green Cone accelerator powder should restore the bacteria population and restart the digestion process.

When and how often should I empty my Green Cone?

In a well operating Green Cone, the waste residue will only need to be removed every few years. It requires emptying when the residue builds up to about 10cm below ground level and shows no signs of reducing.

How do I get more accelerator powder?

Additional accelerator powder can be purchased by contacting Green Cone Ltd using the freephone number 0800 731 2572.

Will the Green Cone attract flies?

The Green Cone is a sealed unit and when installed properly does not produce smells. It does not therefore attract flies. However the eggs of fruit flies are often present on the skins of fruits and can hatch out in the Green Cone. Similarly, if food or food waste is not kept covered prior to going into the Green Cone, eggs may be laid by a house fly or blue bottle. These would also produce maggots and flies in the Green Cone. Good housekeeping is therefore important. Should flies become a nuisance they can be eradicated using an airborne fly killer such as the organic product ‘Flyko’ which will not kill the bacteria.

Does the Green Cone attract vermin?

If correctly installed, your Green Cone will not attract vermin. By ensuring that the top of the black basket (the digestion chamber) and the bottom lip of the green outer cone are below ground level any smells will be filtered out by the surrounding soil. If you suffer from rats in your garden, you could be unlucky and find that a rat run crosses the Green Cone. If you think there is a chance of this happening, you should put ‘guinea pig’ wire around the black basket to prevent a rat gnawing its way through into the waste.