Harman UK

Garden Compost

Amendment

Garden compost is a valuable, home-made soil conditioner created from decomposed garden and kitchen plant materials. It improves nearly every garden soil and turns everyday waste into a useful resource. Use mature compost to mulch beds, enrich new planting areas and support healthy soil life, while choosing peat-free compost for bought growing media.

What it is

Finished garden compost is dark, crumbly and earthy-smelling, with most original ingredients no longer recognisable. It is made by microbes and small organisms breaking down a balanced mix of nitrogen-rich green materials and carbon-rich brown materials. Grass clippings, vegetable peelings, prunings, cardboard and fallen leaves can all contribute in suitable amounts. Compost improves soil structure and moisture retention and supplies modest nutrients gradually. It is a conditioner rather than a precise fertiliser. Cold, dry or overly woody heaps decompose slowly, while a heap with enough air and moisture matures more reliably.

What to do

Build a heap or use a bin in a convenient, partly shaded place. Add a varied mix of green material, such as soft weeds without seeds and vegetable peelings, with brown material such as dry leaves, shredded prunings and torn cardboard. Keep it damp like a wrung-out sponge, but not saturated, and turn it when practical to introduce air. Use mature compost as a surface mulch or work it into a new bed. Keep diseased material, perennial weed roots and seed heads out if your heap does not become reliably hot. Choose peat-free compost when buying material for sowing or containers.

Tips

Start using compost when it smells pleasant and crumbly, even if a few coarse pieces remain; return those pieces to the next heap. Do not rely on compost alone for every nutrient need in heavily cropped vegetables. Cover the heap in prolonged rain. A separate leaf mould store makes better use of autumn leaves.

Garden Compost: frequently asked questions

What is garden compost?

Finished garden compost is dark, crumbly and earthy-smelling, with most original ingredients no longer recognisable.

How do I improve garden compost?

Build a heap or use a bin in a convenient, partly shaded place.

What are some tips for garden compost?

Start using compost when it smells pleasant and crumbly, even if a few coarse pieces remain; return those pieces to the next heap.

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General guidance for UK gardens and allotments. Page updated 18 Sep 2026.