Composting fruit, leaves and garden waste

Getting Started

Tips for producing great compost 

You can compost garden waste, raw vegetables and fruit in any type of composter but if you would like to compost cooked food and meat products you will need a special composter. These are sealed and made of metal and so are rodent proof - very important in a schools situation. Click here for more details.

For help composting in your school see Devon Community Composting's useful guide;  Compost - School Special.

 Just like us a compost needs air, moisture, warmth and food to survive, and so we advise following this 4 point mantra:

Air

• Air is provided by the woodchip and or sawdust that you mix with the food waste. This is preferably from softwood and must not be sawdust from MDF or other composite wood with glue materials or tanalised timber etc.

Water

• Raw fruit and veg is mostly water so it is rare that you need to add more, however the maturation system (often a Scotty’s Hot Box) can dry out especially if paper towels and cardboard are added – if this is the case add water, preferably rainwater.

Warmth

• The Jora, Scotspin, Ridan and Hot Box are all insulated to maintain warmth and the Hot Box is that size so that the mass of material also helps it to self insulate.

Food – balanced diet

• Food – the food you add to the compost heap has to be the right balance of carbon to nitrogen, yet food wastes are predominately nitrogen rich which means there has to be a supply of carbon brought in, this is also vital for the air element, so sawdust and woodchip fit the bill perfectly.

• Food must be added fresh every day as it arises. If you leave it festering in a bucket it will go anaerobic (without air) and get very smelly and then it is much more difficult to get composting properly.

• Fruit waste is pretty acidic and the first hot stage of composting needs to be neutral or slightly alkaline, woodchip and plenty of air helps balance the pH and some shredded up cardboard is good as that is also alkaline.  Although, cardboard should not be added to tumbling systems in any large quantity as they tend to absorb too much moisture, do not offer and structure allowing air flow and tend to conglomerate into balls.

Other considerations

• The school is advised to change the job description of the main person responsible for the composting, usually either the caretaker or a teacher (preferably both) so that their duties include time spent maintaining the composting (and recycling).

• Involving the children as much as possible is desirable to ‘embed’ the system into the school ethos.

• Training must be given to all those who are going to work with and handle the compost particularly in regard to Health and Safety. You should write your own health and safety policy and risk assessment relating to composting, please use the templates provided as a guide.

How it works

• Composting goes through four stages – first it gets warm, then, if the mantra has been followed properly it will rapidly progress to being hot. Turning to mix and aerate as new food waste is added will maintain the temperature as long as fresh materials are being added and will accelerate the composting process.

• As long as the materials have started to break down and are heated up in the tumbler they can be added to the maturation container. At this stage the material is only partly composted and it can vary enormously and it can be rather wet and smelly depending on how much your school is putting through the system, and how well you are following the composting mantra. It is an opportunity to rectify problems, for instance you can layer in paper towels or cardboard to soak up excessively wet materials or  conversely to add moisture to a dry mix use fresh green garden clippings or sprinkle with (preferably) rainwater.

Starting a new compost system from scratch

• When you first start a new composter from scratch it is always advisable to add a good dollop from another compost heap in order to get a starter culture of bacteria and other micro organisms.

• During the start up phase – for the first few weeks or month, it’s best to make sure that the air supply, in the form of woodchip/sawdust is higher than is needed rather than less. If you start a system with not enough structure it can easily go airless and start to smell and then it’s difficult to get it back on track.

• When you first start composting it is also advisable to limit the materials as far as possible to fresh peelings rather than tackling the cooked fraction, introduce this element gradually as and when the compost is steaming away nicely.

• Cardboard is also a good substance to add in small amounts at the beginning of the composting process as it helps balance the pH, cardboard dust is even better if you can get it or cardboard shredded for bedding. Be careful of adding too much that it balls up and dries the composting material out too much. 

Adding materials

Different recipes are applicable depending on what types of materials you have:

1) for cooked food, plate scrapings, left over unserved food

Rule of Thirds:

One bucket fresh raw peelings etc to One bucket of cooked food and One bucket of dry woodchip/sawdust. (you may need to add extra woodchip/sawdust if the cooked food is particularly dense, wet and heavy.)

2) for mostly raw fruit and vegetable peelings etc

50 /50

roughly equal volumes of fresh materials with woodchip/sawdust

NB these are just guidelines and you can augment food waste composters with garden clippings just balance the ‘browns’ and ‘greens’ as much as possible.