Why Compost in a Small Space?

You do not need a sweeping lawn or a corner of an allotment to make your own compost. A balcony, a courtyard, a narrow side return or a paved back yard can all produce beautifully crumbly, dark compost that your pots, hanging baskets and borders will adore. It saves you money on bagged compost, keeps green waste out of your bin, and gives you something genuinely useful in return for a few minutes of pottering each week.

The trick is scale and control. A small heap that is left to its own devices in a rainy British autumn will turn slimy and sulky. A small bin or wormery that is managed properly will quietly get on with the job, even in a space no bigger than a wheelie bin footprint. Here is how to make that happen.

Compact Bin or Wormery?

Both work. They suit slightly different gardens and slightly different gardeners, so it is worth picking the one that fits your habits rather than the one that looks neatest in a catalogue.

• A compact bin (often around 100 to 220 litres) is best if you have prunings, deadheading, spent bedding plants, grass clippings and a good supply of cardboard. It needs air, moisture balance and occasional turning. It takes cooler, slower compost and can handle a wider range of garden waste.
• A wormery is best if you have limited outdoor space, no room to turn anything, or you want a faster, richer product. It runs on kitchen scraps, soft garden waste and shredded paper, and it produces both a crumbly castings mix and a liquid feed you can dilute for hungry containers.

Many small-space gardeners run both: a bin for the bulkier garden waste, a wormery for the softer material and the liquid gold that comes with it.

Building a Bin That Does Not Smell

The single most common cause of a smelly compost bin is too much wet, green material and not enough air. When the contents go anaerobic, you get that sour, sewage-like whiff. Fix the balance and the problem disappears.

Aim for roughly equal volumes of greens (grass clippings, soft plant growth, fruit and vegetable peelings, tea leaves, coffee grounds) and browns (shredded cardboard, torn paper, egg boxes, woodchip, dried leaves, straw, the contents of your paper shredder). In a small bin, err on the side of more browns, especially through a wet summer.

• Site the bin on bare soil if you can, so worms and drainage can do their work. If it must sit on paving, put a layer of twiggy prunings in the base first.
• Chop everything smaller than your thumb where you can. More surface area, faster results.
• Add greens and browns in thin alternating layers rather than one big dump of clippings. Never add grass clippings more than a couple of centimetres deep.
• Turn the contents every fortnight or so with a fork or a small compost aerator. This is the single best way to keep a small bin sweet.
• If it is too dry, add a little water and a handful of fresh greens. If it is soggy, add shredded cardboard, give it a stir and check the base is draining.

In winter, everything slows down and that is perfectly normal. Insulate the bin with an old sack or a piece of carpet, keep it out of the coldest wind, and be patient. You will still have compost by late spring.

Wormery Wisdom

A wormery is a small, living system and it rewards a light touch. Keep it out of full sun and away from frost, somewhere between 15°C and 25°C for most of the year.

• Add food little and often. Overfeeding is the main reason wormeries turn sour. If there is uneaten food after a week, hold back.
• Chop or freeze scraps first. Freezing breaks down cell walls and speeds everything up.
• Keep the bedding as damp as a wrung-out sponge. Add shredded paper or coir when it gets wet, sprinkle with water when it gets dry.
• Drain the liquid every week or two. Dilute it roughly one part to ten with water and use it on pots, tomatoes and hungry flowering plants. Undiluted, it will scorch roots.
• Go easy on citrus peel, onions and anything oily. A little is fine; a weekly heap of orange peel is not.

What to Leave Out

Keep small-space systems simple and trouble-free by excluding cooked food, meat, fish, dairy and pet waste from an open bin. Leave out perennial weeds such as bindweed, ground elder and couch grass roots, along with diseased plant material, seeding weeds and anything treated with weedkiller. These either survive the process or attract pests. Add glossy magazines, sticky tape and cat litter to that list too.

Using Your Compost

When the bottom of your bin looks dark, crumbly and smells of woodland floor, it is ready. Sieve out any lumpy bits and return them to the next batch.

Use it as a mulch around borders, a top dressing for established shrubs, or mix it with grit and coir for containers, roughly one part compost to two parts growing medium so you do not overwhelm young roots. Worm castings are strong stuff, so use them sparingly in seed mixes and generously as a top dressing.

Nothing in a small garden is wasted, and nothing needs to leave in a plastic sack. A tidy bin, a happy wormery and a fortnightly stir are all it takes.