Compost heap or compost bin: pros, cons and advice for your garden

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At the bottom of the garden, two schools of thought have always gone head to head: the good old compost heap, which our grandparents tended with a fork, and the closed bin, more discreet and more modern. Both work, and the compost they produce is the same. What differs is the space they need, the time they take and the peace of mind they offer.

Here are their respective pros and cons, a look at multi-bin systems, and our advice according to the size of your garden.

The heap: free and with no volume limit

A compost heap is the simplest form there is: you pile your waste directly on the soil, in a corner of the garden. Aim for a height of roughly 50 cm to 1.5 m: any lower and the heap dries out and cools down too quickly; any higher and it compacts and lacks air in the centre.

Its strengths

• It costs nothing and needs no assembly.
• It has no volume limit: ideal when the garden produces lots of grass cuttings, leaves and prunings.
• It is easy to turn with a fork, since nothing gets in the way.

Its drawbacks

• It is slower: allow six months to a year before you get mature compost.
• It is exposed: rain washes it out, sun dries it up and wind scatters it.
• It attracts animals: cats, dogs and rodents are happy to rummage through it, especially if you add kitchen scraps.
• It is less discreet, which can be a nuisance in a small garden or near a shared fence.

To set one up, choose a spot in partial shade, sheltered from the wind, on ground that doesn't stay waterlogged, and away from the neighbours. An old tarpaulin or a piece of cardboard laid over it in winter protects it from heavy rain without smothering it.

The bin (silo): clean, compact and faster

A bin, or silo, is a composter enclosed on all sides and fitted with a lid, made of wood or plastic. It too stands directly on the soil. A bin can hold up to 1,000 litres and, in theory, produces ready-to-use compost in around four to five months. In practice, we advise allowing four to nine months depending on the season and how well it is looked after.

Its strengths

• It retains heat and moisture, which speeds up decomposition.
• It keeps animals at bay, and kitchen waste stays out of sight.
• It is compact and clean, so well suited to small gardens.

Its drawbacks

• Its volume is limited: in spring, one big mowing session can fill it in one go.
• It is harder to mix than a heap: you stir the top layer, about twenty centimetres deep, each time you add material, and a suitable tool such as the Brass'Compost helps a great deal.
• It has a cost, although many local councils offer them at a reduced price.

When choosing, look for a sturdy, well-made composter from a reputable maker, built to last. Wood or plastic? Wood breathes and blends in well with the garden; plastic is light and needs no maintenance. We go into choosing and looking after a wooden model in our guide Wooden composter, and cover the drum you turn by hand in our guide Rotating composter.

Key points

A heap is free and unlimited, but slow and exposed. A bin is faster, cleaner and more discreet, but its volume is limited.

The 2- or 3-bin system

A single bin has one drawback: fresh waste is constantly mixed with almost-mature compost, and you have to wait until everything has broken down before emptying it. The solution is to set up two bins side by side:

• the first takes the fresh waste, as you add it;
• the second is for maturing: when the first is full, you transfer its contents into the second, making sure the oldest material goes back at the bottom, then start filling the first one again.

A third bin, or a simple crate, can be used to store dry material (dead leaves, shredded prunings), always close at hand to balance what you add. In large gardens, bays made from pallets do the job very well; in that case, check that the wood has not been chemically treated.

If you have more than 1,000 litres of waste to compost, it is better to switch to two bins than to look for a giant model. On the diagram: the bin being filled (1), the bin maturing (2) and the mature compost, ready to be sieved (3).

Timescales compared

Sources don't all give the same figures, as everything depends on the season, the mix and the care you put in. Here are some realistic estimates:

• Heap: six months to a year.
• Bin: four to five months in good conditions, more like four to nine months if you include winter.
• Two-bin system: the same breakdown time, but a more regular harvest, since one bin matures while the other fills up.

Finally, bins of less than one cubic metre are generally less efficient than large ones, but they work very well, just more slowly: a small bin is therefore still an excellent choice for a small garden.

Animals, rain, neighbours: points to watch

Animals

An open heap attracts animals looking for food. If you compost your kitchen scraps, bury them in the centre and cover them with dry material, or opt for a closed bin. Our guide to composter pests details effective protection.

Rain and drought

Compost should stay as moist as a wrung-out sponge. An uncovered heap can get waterlogged in winter and parched in summer; a bin with a lid limits these extremes, but sometimes needs watering during hot summers.

Neighbours

Well-balanced compost doesn't smell. Even so, place it away from the property boundary and neighbours' windows, and behind a hedge if possible: it's more pleasant for everyone.

Willy's tip

A heap doesn't have to be shapeless: four stakes and some wire mesh are enough to contain it. It takes up less space, looks tidier and is just as easy to turn: simply open one side.

Our advice according to garden size

• Small garden or courtyard, mainly kitchen waste: a bin of around 300 to 400 litres, or a rotating composter if the ground is paved with concrete.
• Medium-sized garden, with lawn and a few hedges: a bin of 400 to 600 litres, together with a store of dry material.
• Large garden, vegetable plot, orchard: a two- or three-bin system, or one bin for the kitchen and a heap for large volumes of garden waste.

These guidelines, similar to those given by a number of local councils, are explained in detail in our guide What size composter?. A wooden bin such as our Compostys wooden composter is ideal for getting started, and there's nothing to stop you adding a second one later. If you are still torn between garden compost and worms, our guide Wormery or traditional composter will help.

In summary

A heap is free, unlimited and easy to turn, but it is slower, exposed to the weather and attracts animals. A bin is faster, cleaner and more discreet, at the cost of limited volume. For a small garden, one bin is enough; for a large one, two or three bins, or a bin combined with a heap, mean you always have one batch of compost in progress and another maturing. Either way, keep a store of dry material close by.

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