02/03/2026
A raised bed does not need to be filled with expensive bought compost. This layering method turns free materials into fertile growing medium while avoiding the considerable cost of purchasing topsoil and bagged compost by the cubic metre. 🌱
The technique works through decomposition speed: each layer breaks down at a different rate, releasing nutrients gradually over months. The cardboard base suppresses weeds and retains initial moisture. Branches create air pockets and drainage (the hugelkultur principle). Green materials supply nitrogen, brown materials provide carbon, and together they convert into stable humus.
How to build it, layer by layer from base to surface:
Cardboard base — plain brown cardboard, overlapped with no gaps, tape and staples removed. Blocks weeds and retains moisture from the first watering.
Branches and sticks — thick and thin mixed together. Creates structure, air pockets, and long-term water retention as the wood slowly absorbs and releases moisture. Branches break down over two to three years, continuing to feed the bed.
Green materials — fresh grass clippings, annual weeds (before seeding), fresh kitchen vegetable scraps. These decompose quickly and release nitrogen.
Brown materials — fallen leaves, straw, dry plant stems, torn cardboard. Two parts brown to one part green is the ratio to aim for. If green dominates, the heap ferments and smells.
Kitchen scraps — fruit and vegetable peelings, coffee grounds, eggshells, teabags. Mix with brown material. Never add meat, dairy, or cooked food with oils.
Top layer: compost — 10 to 15 cm of good-quality compost. This is the layer you plant directly into on day one. The lower layers take six to twelve months to break down fully, but roots follow the decomposition downward as it progresses.
Key points: water each layer thoroughly as you build. Dry materials do not decompose. The bed should feel as damp as a wrung-out sponge. Expect the bed to settle by 30 to 40 percent in the first year as materials compress — simply add more compost to the surface to maintain the level.
🌱 Free materials. Layering technique. Rich growing medium within two years.