Composting is a great way to reduce waste and make useful material for your garden. Now that NSC is charging annually for the green bin service and offering cheap compost bins maybe it's time to make a start.
Most gardeners cold compost, and it can take 12 – 24 months to get good compost this way. An alternative is to hot compost and this is a lot quicker, but also trickier unless you spend quite a lot of money on a hot compost bin – basically that is a really well insulated bin that means to rotting material gets properly hot.
COLD COMPOSTING
This guide is adapted from the Royal Horticultural Society website.
See for more from the RHS: https://www.rhs.org.uk/advice/profile?pid=444
Composting is useful in all gardens. Only in the very smallest gardens will it be difficult to find space for a compost heap and material to fill it. Owners of such small plots could consider worm composting instead.
Composting is done all year, as and when suitable materials are generated in the garden or home. However late summer to early winter is the peak time for making compost.
The site and container
It is important that the site is not subjected to extremes of temperature and moisture, as the micro-organisms (bacteria and fungi) that convert the waste to compost work best in constant conditions. Position the bin in light shade; it is often more convenient to use a shady area of the garden.
An earth base allows drainage and access to soil organisms, but if you have to compost on a hard surface, then add a spadeful of soil to the compost bin.
Bins retain some warmth and moisture and make better compost more quickly, but even an open heap (not enclosed in a bin) will compost eventually. Any of the compost bins on the market should produce compost as long as they exclude rain, retain some warmth, allow drainage and let in air.
Bins less than 1 cubic m (1.3 cubic yd) in size are much less effective than larger ones.
Getting the right balance of composting materials
- Aim for between 25 and 50 percent soft green materials (e.g. grass clippings, annual weeds, vegetable kitchen waste, or manure) to feed the micro-organisms
- The remainder should be woody brown material (e.g. prunings, wood chippings, paper, cardboard, straw or dead leaves)
Avoid letting any one material dominate the heap - especially grass clippings, as these can become a slimy, smelly mess on their own.
Kitchen waste and grass clippings are best mixed with brown woody material, as they tend to be wet and easily compacted, excluding air.
Some common composting materials
- Green: Grass clippings; soft, leafy plants including annual weeds; fruit and vegetables, uncooked kitchen waste; selected pet waste/bedding
- Brown: prunings and shredded hedge trimmings, woodchip, leaves, paper and card (torn up or shredded), straw, plant stems
- Accelerators and activators: Products such as ‘Garotta’ are sometimes added where green waste is in short supply. They contain high levels of nitrogen (a nutrient found in green waste), but should not be necessary if green waste is plentiful. It is also possible to purchase activators containing carbon (a nutrient found in brown woody waste); these are aimed at composting grass clippings or other green waste where there is insufficient brown waste
- Lime: People sometimes think you need to add lime to the compost heap, but there is no need to do so
Turning the heap
Ideally, place a lot of composting materials on the heap in one go, and turn it periodically (perhaps every month) to introduce air. Failure to turn the heap is probably the main cause of poor results.
Many gardeners are unable to fill the heap in one go, as they accumulate waste gradually. Because of this, home-made compost is seldom as perfect as municipal compost, but it is still effective.
Remember to keep the heap moist in dry weather – turning will give you an opportunity to assess the moisture level.
When is the compost ready?Garden compost can take between six months and two years to reach maturity. Mature compost will be dark brown, with a crumbly soil-like texture and a smell resembling damp woodland.
It is unlikely that all the material in the heap will be like this, but any remaining un-rotted material can be added to the next batch of composting materials.
Problems
Sometimes the results of composting are not as expected.
Wet, slimy and strong-smelling compost: Too little air and too much water are often to blame. Cover the heap to protect against rain and add more brown waste, such as chopped woody material, shredded woodchip, straw or paper.
Dry and fibrous with little rotting: Usually caused by too little moisture and too much brown material. Add more green waste, or try a commercial activator or accelerator such as ‘Garotta’. Alternatively, add fresh manure at one bucket for every 15cm (6in) layer of compost, fish, blood and bone fertiliser at 270g (9oz) per 15cm (6in) layer of compost, or sulphate of ammonia fertiliser at 140g (5oz) per 15cm (6in) layer of compost.
Flies: Well-run compost bins don’t produce swarms of flies, but if you do see these, then make sure you cover kitchen waste with garden waste after adding it to the heap and check that moisture levels are not too high, causing insufficient air in the heap.
HOT COMPOSTING WITH A BIN
This Guide is adapted from the Ideal Home website. The site offers advice for hot composting without a specialised bin and if you want to know more about that go to https://www.idealhome.co.uk/garden/hot-composting-247917
The big advantages of hot composting are that it produces compost much more quickly, and can take pretty much any kitchen waste, including cooked food and meat which should never go into cold compost. Its advocates say it makes a better compost as well.
If you like the idea of hot composting, but don’t have the time to spare to make it from scratch, it might be worth investing in a hot composting bin. In 2019, HotBin – a hot composting bin – won garden product of the year at the Chelsea Flower Show.
These bins help simplify the hot composting process. The bin maintains a steady temperature of 40 to 60 degrees C, even in winter. All you need to do is regularly add food or garden waste, and a bulking agent or shredded paper to keep the air flowing inside the bin.
However, these bins don’t come cheap – they usually cost over £100 and can cost up to £400. But hopefully, they will save you money on bags of compost in the long run.
If you do decide to invest in a hot compost bin there are a few tricks to make sure that you get the best out of it.
It is best to combine food and garden waste, The more waste the better as this speeds up the rate that the process works. At least 50 per cent capacity is recommended to get the best results.
It’s best to mix up the waste you add, so don’t just add all paper one week and grass the next. One option to avoid this is to save it up and add it all in one go as a mixture. Just be sure to make sure there is a mix of moist and dry materials.
It is also a good idea to break waste up into small pieces, like with the manual hot composting process. This will help speed you on your way to sumptuous compost in no time at all.