If you have a patch of garden, you can make compost outside without buying a rotating drum or complicated kit. Garden waste naturally decomposes; your task is to help it happen in a way that does not create a smelly heap or attract pests.
An open compost heap can work well for leaves, chopped stems, plant trimmings and other suitable materials. A simple three-sided wooden bay gives more structure, but it is the balance of ingredients, moisture and air that matters, not how expensive the container looks.
Choose a sensible outdoor location
Pick a sheltered spot you can access easily with a wheelbarrow or bucket. The Royal Horticultural Society generally recommends shade or partial shade for an outdoor compost setup, which helps prevent extreme drying and overheating.
A level soil base gives useful drainage and access for soil organisms. Do not build a heap directly across a drainage channel or against timber cladding that could stay perpetually damp.
Leave enough working room at one side. A compost heap you cannot turn safely will become frustrating, and you may end up throwing everything on top without ever using the finished material.
Decide between a heap and a bay
For a simple heap, begin with suitable coarse garden material and add mixed waste in a roughly rectangular pile. It does not have to be perfectly shaped, although keeping it contained makes turning easier.
A bay constructed from sound recycled pallets or untreated suitable timber can tidy up the area. Secure any structure so it cannot fall, and remove protruding nails before working near it.
The RHS suggests larger heaps are generally more efficient because they retain some heat, but even a modest heap will decompose given time. Avoid building an enormous unstable mountain that is difficult to manage.
Gather greens and browns
Fresh grass clippings, vegetable trimmings and soft leafy material are examples of nitrogen-rich greens. Fallen leaves, straw, shredded cardboard and chopped woody stems are carbon-rich browns.
A pile of fresh grass by itself quickly becomes compressed and unpleasant. A heap made entirely from dry leaves can be very slow. Mixing the two provides a better environment for decomposers.
You do not need to follow a laboratory-precise formula. Start with approximately comparable volumes of soft greens and somewhat more browns, then adjust if the heap is wet, dry or slow.
Build a loose, breathable base
Lay a small amount of coarse chopped twigs or dry stems as a loose base. This can help create spaces for air without turning the bottom into a pile of branches that will never rot.
Add mixed greens and browns in manageable layers and lightly blend them with a fork. Do not compact the material by jumping on it or pressing it flat.
If you have a lot of autumn leaves, shred some and keep the rest dry for future additions. Leaves are valuable when you need to balance wet kitchen scraps or grass later in the year.
What belongs in an open heap?
Most normal plant-based garden waste, vegetable peelings, fruit scraps, used coffee grounds and suitable uncoated paper can go in. Chop thick stems into smaller pieces before adding them.
Keep plastics, glass, metal, garden chemicals and treated timber out. Avoid perennial weed roots and seeding weeds you cannot confidently control; a cool heap may fail to kill them.
For a basic open heap, avoid meat, fish, dairy and pet faeces. These can attract pests and create food-safety concerns, and ordinary home compost often does not reach controlled sanitation temperatures.
Manage rainfall without sealing the heap
Rain is useful because decomposers need moisture. Persistent heavy rain can turn an uncovered heap into a saturated mass, particularly during a wet UK winter.
A breathable cover or suitable tarpaulin can reduce direct rain while still allowing some air to circulate. Do not wrap the pile into a completely airtight plastic bag.
During dry spells, lift the top and feel inside. If the material is dusty, moisten it lightly as you turn. You want the dampness of a wrung-out sponge, not a puddle.
Turn it when practical
Use a fork to move outer materials into the middle and loosen compacted sections. Turning helps introduce oxygen and distribute moisture. Wear suitable gloves and take care with unstable footing.
How often you turn depends on your goal. A carefully managed heap may be turned regularly to encourage faster decomposition; a relaxed garden heap may need only occasional attention.
Do not overstrain your back. If the heap is too heavy, build two smaller bays or use an aerator. Composting is supposed to save work, not create a lifting injury.
Composting during winter
Cool weather slows the activity of bacteria and fungi. An outdoor heap can seem inactive in January and begin changing again when the weather warms.
The RHS recommends protecting winter heaps from excessive wetness and maintaining a mix of greens and browns. A little added coarse material can stop wet leaves clumping.
You can continue adding suitable waste, but do not expect a small cold heap to behave like an industrial hot-composting facility. Time is part of the process.
How to avoid smells and pests
An earthy smell is normal; a rotten, sour odour often indicates poor airflow and waterlogged material. Turn the pile and add dry browns. If it is dry and fibrous, do the opposite and introduce moisture and some greens.
Cover fresh vegetable scraps within the pile rather than leaving them on top. Keep meat and rich cooked leftovers out of an exposed heap.
If you spot rodents, stop supplying attractive food waste and review your setup. Do not assume a larger lid or more compost accelerator will solve a badly managed food source.
When is the compost ready?
Finished compost should be dark, crumbly and smell like woodland soil. The RHS gives a broad range of six months to two years, depending on heap size and conditions.
You may find fully decomposed material below the newer additions. Remove that portion and return recognisable stems, large leaves or paper clumps to the active heap.
Do not mistake a black wet sludge for ready compost just because it is dark. Texture and smell matter.
Use compost where it helps
Spread mature compost around shrubs, perennials and vegetable beds as mulch or a soil improver. Avoid burying plant crowns in a deep wet layer.
Home compost improves organic matter and soil structure, but is not a precise fertiliser or universally suitable seed compost. If you need a growing medium for a particular crop, use an appropriate blend.
A simple outdoor pile is inexpensive and effective once it has a little routine. Add mixed materials, keep it damp and airy, turn when you can and use it when it has truly broken down.