A beginner’s guide to composting

The times they are a-changing. Well, they are in terms of how humans relate to this planet. While we are far from becoming a species in natural harmony with our environment, there are signs of change that give us serious hope for the future. One area of optimism is the growing interest in growing food and, as a result, composting.

Once the preserve of professional gardeners and hippies, composting has recently been embraced by a new army of dedicated recyclers, keen to do the right thing.

Composting is a natural process whereby organic matter breaks down to create humus. In nature this happens all the time when green plant matter dies or falls from trees or shrubs, but since the middle of the last century, we humans have begun to understand the process of decomposition and the importance of organic matter in the soil.

With rapidly reducing rainfalls, caused by climate change, compost has been found to be invaluable as it retains moisture in the soil and acts as a buffer against extreme environmental conditions.

While you can be extremely technical about making compost, the non-scientist should approach the process as if they were a cook trying to make a cake. For a successful end result — be it a cake or garden compost — you need the right ingredients in the appropriate quantities as well as sufficient water, adequate air and the appropriate “cooking” time.

While anything that once lived can be composted, it’s best to stick to reliable ingredients such as grass clippings, kitchen scraps, leafy garden prunings, shredded paper, fallen leaves and even old potting soil. The value of your compost relates to the quality of the ingredients, the position and size of the compost heap, the ambient temperature and the amount of time you spend turning the pile.

Large gardens

Those with large gardens can compost on a big scale. The popular choice is to have three compost bays — or bins — placed next to each other. The bins are usually made of hard wood (ideally non-cyanide-treated) and are exposed to the earth at the base below. In the first bay, you place all your fresh green matter — grass clippings, garden prunings, fallen leaves, kitchen scraps, shredded paper and added water. After this has been in the heap for a couple of weeks, it can be turned into the next bin.

The process of turning the pile mixes the ingredients and introduces air to the centre of the heap. At this stage, check to see if the mix is moist enough; if it’s too dry, the compost will take ages to break down; too wet and it will become smelly. With the right mix of ingredients, as well as air and water, the heap should become hot and “steamy”. If this is not happening, the mix requires more air and more, or less, water and perhaps some Dynamic Lifter or manure to give it a kick-start.

After a couple more weeks “cooking”, the second bin can be turned into the third bay. Again, check moisture levels when you turn it and make sure all the heap has become brown. Depending on weather temperatures, the compost should be ready to use in a couple of weeks.

Small gardens

The principles of composting are roughly the same for small gardens as they are for large ones. The main difference is you are unlikely to create enough green waste to fill three bins and, even if you did, you wouldn’t have the room for them in the garden. However much you like composting, these bins are not what you want to see, especially in a small garden. Also, they are best hidden away from direct summer sunlight as too much heat can kill beneficial worms, insects and bacteria.

The best solution for small gardens is to have two small plastic compost bins. In the first bin, place your green waste; as you haven’t the mass of a large bin, it’s very important you make sure the green waste mix is varied and that moisture levels are just right. The ideal mix for a small bin is layers of kitchen scraps, shredded paper, coffee grounds, grass clippings, cut-up green garden prunings and even human organic matter such as hair and urine (potty pee is fantastic in compost and around citrus trees).

Avoid bread, citrus, onions, meat, weeds and “number twos”. While all these products can be composted, they can upset your bin’s fauna, attract vermin and possibly introduce potentially poisonous diseases into your garden soil. For those who want to explore ways to compost animal poo, there are well-designed compost pits (advertised in specialist garden magazines) suitable for this purpose.

While not all organic materials are suitable for the small compost bin, they don’t have to be chucked into the rubbish bin. In recent years, most local authorities have provided a green waste bin. This collected green waste is broken up and composted in huge scientifically controlled heaps which, unlike home compost bins, go to very high temperatures that kill all weed seeds and harmful bacteria. Some of these large heaps incorporate human waste (sourced from sewage plants) in the composting process.

After processing, your council green waste is made into compost, which is added to commercial potting mixes and other horticultural products. While we don’t get a direct financial return on the contents of this bin, the community does. So when we quibble about what goes into our own garden compost systems, we should make sure that kitchen waste such as citrus, egg shells, onions, pineapple tops and pumpkin seeds as well as garden weeds and twigs are not wasted by being thrown out with our general rubbish.

For those living in apartments and townhouses, composting in large bins is impractical, so the combination of worm farming and selective use of the council green waste bin is often the answer. The rewards for householders are worm castings and nutrient-rich “worm-juice”, which can be used as a fertiliser on house and balcony plants. All the worms ask is that they are given adequate protection from direct sunlight, extreme cold and drying winds, so very sunny balconies should be avoided.

Children love worm farms and with some basic instruction they can be given sole responsibility for their care. Unlike the large compost bins, worm farms do not get hot, so care must be taken to provide adequate food for your wriggling army of recyclers. While worms love vegetable scraps, some shredded paper, human hair, teabags, old cotton shirts and green leaf prunings, they hate onions and citrus.

After a couple of weeks of feeding you can harvest your worm castings, or vermicompost. To collect the nutrient-rich castings, move the worms to one side and add new food to the other side. Your worms will migrate into the new food source, making the worm-free vermicompost accessible.

When things go wrong

However experienced you are at composting you will sometimes have problems. Smelly compost is usually a symptom of an anaerobic mix, probably caused by not enough air getting into the pile. This often happens when you have too much of one kind of ingredient, such as leaves or cut grass, or may indicate lack of turning of the heap. To solve the problem, you need to demolish the smelly heap and put it aside, close by.

Before you rebuild the pile, it’s best to ensure better access for air and water to the heap by making a compost chimney. To make this, you buy — or recycle — a plastic downpipe, which you cut to a little larger than the height of your heap. Score large holes with an electric drill at regular distances along the pipe — every 10cm is ideal — and place at the centre of the new heap. Holding the pipe upright with one hand, slowly rebuild the heap, making sure the green material is well mixed. If the old pile was too wet, add some dry materials such as lucerne hay or shredded paper.

When the heap is rebuilt, continue as you would for a new compost pile. The compost chimney should stand proud of the pile and will allow air and water to get to the centre of the heap. Sticking the hose into the top of the chimney will allow water to get to the core of the pile. This idea has become very popular with home gardeners in recent years and makes better and faster compost with little expense. While one compost chimney is sufficient for a small moulded compost bin, two or three will be more efficient in larger heaps.

While it’s hard to deter foraging rats and mice, they can become a real problem if they decide to nest in your heap. Rodents living in the bin indicate you have provided not only a reliable food source but a well-drained, warm home. The best way of getting rid of these creatures is by regularly working the heap with a garden fork and applying human urine to deter them. Rodents love cereals, so their presence can indicate that you — or someone else in your home — is putting bread and other cereals in the compost bin.

The most common pests associated with compost heaps are flies. You have to put up with some flying insects near your heap as they are attracted to this nutrient-rich environment. One way to reduce the problem is to keep your pile covered. For the smaller bins, use an old hessian or plastic sack over the heap and close the plastic lid. For larger heaps, it’s best to cover the heap with a piece of large weighted-down plastic. This will deter flies, warm the heap and protect the pile from excess rain.

Composting made easy

Many of us lead busy lives and we often have difficulty turning the compost heap. As regular churning is essential for a good result, many gardeners have come up with clever ways to turn heaps without raising a sweat. The best way, especially for small compost heaps, is to add compost worms to the pile.

Common garden worms are great recyclers, but rarely venture into the warmer conditions of the compost heap. Compost worms (available from garden centres) are a species that relish the warmer conditions inside the compost bin and will happily turn your green waste into humus. As they can’t live in the hottest phase of the composting process, they have to have be able to escape to the earth when things get too hot. If the location of your heap avoids direct sun, you’ll find you can rely on your worms to do most of the turning and they will happily breed and multiply without becoming a pest.

The turning barrel compost bin is another easy method. Looking like an oversized tombola barrel, this bin is a large drum mounted onto a metal frame. The gardener simply adds green waste and a little water to the barrel. After closing the small entrance door, you simply turn the barrel by its handle a couple of times a day. This system can produce compost in a couple of weeks in summer. Despite the expense of buying the compost barrel and frame, this method is ideal for people who want compost but don’t want to exert too much energy.

A far cheaper aid to turning conventional heaps is the compost screw. This tool is like an oversized corkscrew that you place in the middle of your compost heap. A slow turn of the handle gently incorporates the mix, bringing deeply buried green waste to the surface. Regular use of this screw-like device, along with added compost worms, will reduce the need for turning your heap.

Despite the occasional setback, compost-making is an enjoyable way to recycle your green waste. Using the compost heap and worm farm, in tandem with your local council-supplied green waste bin, can dramatically reduce your environmental impact and will improve soil fertility in your garden. It’s not only the responsible thing to do, but it’s also good exercise and rewarding.