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:
- Prevents food waste going to landfill, where it produces methane – which leads to global warming
- 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
Composting food waste
1) Worm farms
Worms farms are a fantastic way to compost household food waste. This method involves special composting worms that transform waste into a nutrient-rich compost and a concentrated liquid fertiliser. The worms are housed in a small container and are kept indoors, so this method is ideal if you don’t have a garden. The process is clean and odourless.
What you can feed your worms: fruit, vegetables, cereal, bread, egg shells, tea and coffee grounds.
You should also add 30% carbon, such as egg boxes, unbleached paper and corrugated cardboard.
Foods you shouldn’t feed your worms include: citrus fruits, onions, garlic, dairy and meat, very oily foods and bleached paper.
Making or buying a worm farm
You can buy a worm farm or make your own. For information about buying and maintaining a worm farm, click here. Check out these videos for how to make a DIY worm farm from plastic drawers, swing bins, and tubs!
A word of caution: When worms are put into their new home, it can take them a few days to settle in – and they have been known to try to escape! You can prevent this by shining a light on the worm bin for the first few days, particularly at night. Worms don’t like light, so if they emerge from the bin, they will see the light and go back inside.
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 Bokashi is a method of processing food scraps that uses fermentation. Bokashi bins allow you to pre-process food waste that normally can’t go into an outdoor compost bin or worm farm. You can put most foods into a bokashi bin, including raw and cooked foods, dairy, meat and bread. Because the process happens in a sealed container without oxygen, there will not be issues with pests or odours.
How it works: Food waste is sealed into a small airtight bin that can be kept on a kitchen counter. Bokashi bran is added, which contains bacteria that ferment the food. After 2 weeks, the fermented food is partially broken down.
Finishing the composting process: The fermented food should then be moved to a new location to fully break down into nutrient-rich compost. You can do this by:
- Digging a trench in a garden bed and burying it
- Putting it in a container planter (ideal if you don’t have a garden). Fill the container with 1/3 potting soil, add your fermented food waste and mix with the soil. Cover with soil and wait 2 weeks before planting.
- Adding it to an outdoor garden waste compost bin. While placing unprocessed food waste into outdoor composters can attract rats, they will steer clear of bokashi-fermented food waste.
- Adding it to a worm farm in small amounts, until the worms get used to it (it’s very acidic).
During the fermentation process, a liquid is also produced, which can be harvested from a tap. This can be used to clear drains or diluted and used as a fertiliser for garden plants or house plants.
If you want to keep composting continuously, it’s a good idea to get two buckets so that you can fill one bucket and start filling the other bucket while the first bucket is fermenting.
For more information on setting up and using a bokashi bin, click here.
3) In-vessel compost tumblers
If you have outdoor space and can afford one, tumblers (like these ones from Maze) are an excellent way of quickly composting food waste. Alongside your food waste, you should add high carbon materials (roughly 50/50). 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 and 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 finish composting for several weeks before being used.
Composting garden waste
1) Dalek bins
If you’re looking to compost waste such as garden weeds, grass clippings and crop residue, you can compost these in dalek bins or pallet bins.
- This can be a 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.
2) Pallet bins
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!
Composting food and garden waste together
Hot bins are insulated sealed bins in which you can add kitchen and garden waste. The contents can get hot (up to 60 °C) which can kill weed seeds and pathogens. It can take some careful maintenance to reach these temperatures, but if this is achieved it will be safe to compost cooked food, dairy, meat and diseased plants.
You can also do hot composting in a heap. See here for how to make compost in 18 days using the Berkeley method.
Make sure there is enough oxygen
In most composting systems, the organisms composting your waste (worms, bacteria, fungi etc.) need air to survive. One exception is bokashi, which is an anaerobic process that happens without oxygen.
The contents of compost bins and heaps 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.
As well as introducing air, turning your compost 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.
Control the water content
The organisms in your compost also need water to survive, but if there’s too much water, it will be difficult for them to access oxygen. The composting process will be slow, and anaerobic composting may take place.
Your compost should have the water content of a wrung sponge. Test water content by mixing 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 add some water. If it’s too wet, add more high carbon ingredients.
Balance carbon and nitrogen
In most composting systems, you want to keep a 50/50 ratio between ingredients that are high in nitrogen and high in carbon.
High nitrogen (sometimes called ‘greens’) include: food waste, annual weeds, grass clippings
High carbon (sometimes called ‘browns’) include: tree prunings, twigs and hedge clippings, woodchip, paper and cardboard, straw and dead leaves.
Keeping these in balance will provide the organisms in your compost with the food they need to survive. It will also help you to control the water content of your compost, as high nitrogen ingredients tend to contain lots of water, and high carbon ingredients contain little water.
If you are composting in a big bin or heap, add high nitrogen and high carbon ingredients in layers – this will prevent certain areas being too wet or too dry. If you’re using a wormery, mix torn carboard or shredded paper in with food waste you feed to your worms.
Add surface area
If you are adding big things to the compost, chop them up into smaller pieces. This will provide more surface area and will make it easier for organisms to digest it.
Give it a sniff
A happy compost pile shouldn’t smell bad – this is a sign that it has gone anaerobic (not enough oxygen). You can remedy this by turning the pile or adding materials like woodchips or scrunched up newspaper, which can add air pockets. You may also need to reduce the water content of the pile by adding more high carbon materials.
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!