The Compost Conundrum
Often referred to as the engine room of the allotment, compost heaps are a feature of most plots. They convert what might otherwise go to waste into a free source of nutrients for your plants. Compost making is so fascinating that many articles, web pages and even whole books have been devoted to it. But is all the discussion about nitrogen/carbon ratios, hot composting and cold composting, aerobic and anaerobic composting and NPK values putting some gardeners off making their own?
Equally disconcerting can be the equipment and amount of space dedicated to composting by celebrity gardeners. Gardeners’ World expert Monty Don has a three bay system that would struggle to fit into many people’s back gardens, whereas no-dig guru Charles Dowding’s garden boasts a huge purpose-built wooden structure to protect his compost from the elements. This is all very impressive and useful to the professional horticulturalist but most gardeners and allotment growers don’t have as much space or money to dedicate to their composting effort.
But the amateur grower should not be deterred. Here is a quick guide to compost making.
How to make your own compost
Compost making is a simple, natural process that pretty much looks after itself. Most organic substances can be composted. It will all break down eventually and give you a product that you can safely spread on your soil. It is true that you need a mixture of fresh, green waste (that’s the nitrogen) and dead, dry, woody, brown waste (the carbon). Identifying what material is nitrogen and what is carbon isn’t difficult and the proportions are not as crucial as some might suggest. Researching this on the internet reveals that experts have varying opinions on what the proportions should be.
So what are the basics of composting? Here is all you need to know to make your own compost.
You will need:-
Green material
Brown material
A container (optional)
A fork
Air!
So what is green and what is brown?
Vegetation that is reasonably fresh, still green and soft is green waste. Grass cuttings, kitchen waste and weeds are all green waste.
Brown material is drier, usually having been dead for a long time. Woody cuttings and stems, straw and cardboard can all be added to your compost bin or heap. Ideally woody material should be shredded or cut into small pieces. Cardboard should be ripped into small pieces, and paper shredded or screwed up. Tape and staples should be removed.
What proportion of green and brown do I need?
There is no perfect ratio but about half and half is a good guide to start with. Throughout the main growing season you will probably have more green waste than brown. Straw is a perfect balance to this if you have access to it. Cardboard or shredded paper can also be used. In fine weather dry your green waste in small pile, or several small piles if you have space, this converts it from green to brown.
If your compost starts to look wet and sludgy, you have too much green material. Add more brown and mix it well. If it looks very dry, mix in more green material if you have it, dampen with a little water if you don’t. If using a compost bin it sometimes helps to empty it so that you can mix it more thoroughly.
What shouldn’t be composted?
Do not put meat products, cooked food, dairy products or cat and dog waste in your compost bin.
As much as possible avoid perennial weed roots because they might regrow, and anything that has gone to seed as it is unlikely that a normal sized compost heap or bin will get hot enough to kill seeds. You need not be to pedantic about this. You will be able to spot the roots as you use your compost and weed seeds are very likely to find their way onto your plot whether from your compost or not.
What sort of bin should I use?
You don’t necessarily need a bin at all. You can just build a heap and turn it from time to time. Ideally it will need to be covered to keep the rain out.
Another option is to build a composting bay from pallets which can often be sourced free. Try searching local social media groups. Four pallets tied or nailed together will do the job. Some gardeners choose to line them with plastic to retain some heat and protect the wood, whereas others prefer to leave them open to allow air flow. Either method works but open sides can cause the material around the outside to dry. This can be incorporated into the damper material in the middle when you turn it and often balances the mix nicely so is not necessarily a bad thing.
Plastic ‘dalek’ style bins are a popular and functional choice. They cost a few pounds but are very durable. In some areas they can be bought at a reduced price from the council. They are often available second-hand on local social media groups too.
Dalek bins come in two basic designs, those that have a lid on top and a door at the bottom but otherwise solid sides and those that have ventilation slots in the sides. The solid sided ones retain more heat but reduce air flow. The slotted ones allow better air flow but the contents near the outside can dry out quite quickly. As with the pallet bins, this can be turned into the damper material to improve the mix. I have both types of dalek but prefer the slotted ones.
Note that it is best to put your bin or heap directly on the soil to allow worms and other invertebrates access from below. If possible position your bins in semi-shade but don’t let the absence of shade deter you.
What else do I need to do?
Turn your compost from time to time. This introduces air into the mix which helps to keep the composting process live. If you have more than one compost bin or heap, move the material from one to another, mixing well and balancing the contents if it seems too wet or dry. If you only have one bin, empty it, give it a good mix and put it back in the bin. Any compost that looks ready to use can be spread as a mulch around your vegetables, used in a potting mix, or saved separately until you have a sufficient amount to use.
How long will it take?
Composting is a slow process. In warm weather you might have some useable compost in two or three months but it can take six months or more. Be patient, eventually you will have some very useful compost.
When the compost is a nice crumbly texture and a dark brown colour it is ready to use. It is likely to break down inconsistently. Don’t worry about this, just remove any material that isn’t ready and return it to the bin.
What can I use my compost for?
Homemade garden compost makes an excellent mulch. It can be dug into beds to improve soil or added to planting holes for hungry plants like courgettes and winter squashes. It can also be added to peat-free compost to enrich your potting mix. Homemade compost is not recommended for sowing seeds as it may contain organisms that cause damping off in small seedlings.
Conclusion
There is a lot of science involved in composting and it’s interesting to study but not essential to understand it all. In simple terms composting is just organic material rotting so nobody should be put off by the science. Gather material, mix it, let it rot, use it. You’ll soon be hooked!
Enjoy your composting and your allotment.