What is composting?
Home composting is an easy and eco-friendly way to deal with kitchen and garden waste. Waste is put into a container, where it breaks down and turns into compost, a product rich in nutrients and beneficial micro-organisms which help to support soil and plant health.
Benefits of compost:
- Provides plants with a nutrient boost
- Suppresses plant disease
- Improves soil structure
- Helps maintain moisture levels
- Keeps your soil’s pH balance in check
- Compost heaps are great for wildlife
Kitchen waste composting
Wormeries are ideal for composting household food waste and are suitable for indoors or outdoors. This method requires a special species of earthworms (normally red wrigglers). Wormeries take up very little space and the process is clean and odourless. Two high quality products are produced. Firstly, a very rich compost from the worm castings/poo. Secondly, the liquid/leachate that drains from the bottom (not to be confused with worm tea) can be diluted with water (1:10 parts) to make a liquid plant feed. Do not use it if it smells bad as this is a sign it has gone anaerobic and can contain harmful microbes. Shop-bought wormeries cost about £100, but it’s fairly straightforward to make one at home. Find out how to make your own wormery, look after and feed your worms, and make worm tea.
With the bokashi method, food waste is fermented anaerobically using a bran that contains microorganisms. Bins are small so they are ideal for indoor use. Waste doesn’t fully decompose so it needs to be put in a compost bay or buried in the ground to ‘mature’ – or added to a wormery (do this gradually so the worms can get used to it). It’s suitable for all kitchen waste, including cooked food, dairy and meat. It produces bokashi ‘tea’, a concentrated fertiliser. Bokashi bins cost about £25.
3) In-vessel compost tumblers
While a more expensive option (these Maze tumblers cost around £190), tumblers are an excellent way of quickly composting food waste. Alongside your food waste, you should add high carbon materials (roughly equal amounts). We recommend wood chip, as it creates air pockets which prevent your compost from going anaerobic. Otherwise you could use shredded paper.
Tumblers have a handle which allows you to ‘turn’ the compost to introduce air without much effort. Turn it once a day. Within 2-3 weeks the contents should be unrecognisable. At this point it is ready to go into a pallet bin or heap where it should ‘mature’ and cool for several weeks before being used. While rats can be attracted to food waste (more on this below), rats will not be attracted to the matter removed from the tumbler.
Mixed composting: kitchen and garden waste
1) ‘Dalek’ bins or pallet bins
- Slow process (6-12 months)
- Avoid perennial weeds (couch grass, bindweed etc.) or weeds with seeds
- Avoid plants that are diseased or infested with pest
- No dog poo or cat litter
- Turn regularly with a garden fork, or if using a dalek bin (pictured) a compost aerator. The downside of dalek bins is that they are awkward to get into and turn. If you do use one, it’s a good idea to drill lots of holes in it to increase air flow.
Pallet bins are quick to make and you can often get free pallets from industrial areas, supermarkets and department stores, construction sites, wholesalers and small businesses. Check out this step-by-step guide to making your own bin, or see below for how to make a 3-bin pallet system!
2) Hot bins
Hot bins are insulated sealed bins in which you can add kitchen and garden waste. The contents gets hot (it can reach up to 60 °C) which will kill weed seeds and pathogens. This means it’s safe to compost cooked food, dairy, meat and diseased plants.
You can do hot composting in a hot bin (pictured) or do it in a heap. See here for how to make compost in 18 days using the Berkeley method.
Ingredients for mixed composting systems
- High nitrogen ingredients – these are quick to rot and normally have a high water content. They include:
- Vegetable kitchen waste
- Annual weeds
- Grass cuttings
These are often referred to as ‘greens’ – although they are not always green!
2. High carbon ingredients– these are slow to rot and normally have a low water content. They include:
- Prunings, twigs and hedge clippings
- Paper and cardboard (inc. egg boxes)
- Dead leaves
These are often referred to as ‘browns’.
You’ll want a roughly 1:1 ratio of high nitrogen to high carbon ingredients in cold compost – the ratios can vary for hot composting depending on the method.
3. Add 10% very high nitrogen ingredients – these help to get the decomposition process going, and include:
- Legumes (clover, vetch etc.)
- Manure (only if organic, otherwise can be contaminated with weed killer)
- Coffee grounds
Control moisture, introduce air: Microorganisms in the compost pile need water and air to survive. If there’s too much water in the compost heap, it will be difficult for microorganisms to access oxygen. The composting process will be slow, and anaerobic composting may take place.
Smelly compost? A happy compost pile shouldn’t smell – this is a sign that it has gone anaerobic.
Getting the right balance between ingredients high in nitrogen and those high in carbon will help to introduce air and maintain the correct moisture levels. Woodchips or scrunched up newspaper are useful for adding air pockets.
Layers: Add high nitrogen (high water content) and high carbon ingredients (low water content) in layers – this will prevent certain areas being too wet or too dry.
Turning the compost: Except in the case of wormeries and bokashi, compost should be ‘turned’ (mixed up) regularly with a garden fork or compost aerator (see example). If you use a compost tumbler you can do this by turning the handle. If you use a three pallet bin system, this is done by moving the contents from one bin to the next.
Turning your compost introduces air and moves stuff from the edge of the pile – which will be breaking down slowly – to the middle – where it will break down more quickly – and vice versa.
Testing water content: Mix your compost well then take a handful and squeeze it. If 2-3 drops come out, it’s got the right amount of water in it. If it’s too dry, add more ingredients high in nitrogen or water the pile. If it’s too wet, add more high carbon ingredients.
Chop up bigger bits: The more you chop, the more surface area and easier for microorganisms to break it down.
Monitor and adjust: You don’t have to do everything perfectly from the beginning, just check your compost regularly to see how it’s doing – is too wet, too dry, too smelly, too compact? Monitor and adjust.
How to make leaf mould
Leaf mould is made from autumn leaves. Not only is it super easy to make, it is an excellent soil conditioner, meaning it helps to improve soil structure.
To make it, rake up leaves after they fall in the autumn and put them into bin bags. Add a little water if they are dry, tie up the bags and puncture some air holes. Alternatively, make a cage from chicken wire. It will take about 12 months to break down. Simple!
Using your compost
- Add a few inches to pot plants or garden beds before planting. See here for how to make ‘no dig’ garden beds using compost.
- Use around fruit bushes and trees to help retain soil moisture and prevent weeds. Don’t place it directly against the bark as this could cause rotting.
- Feed your lawn – dressing your lawn with compost helps young grass take root and can make your garden healthier and greener!