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Composting

Homemade compost is the heart of a Square Foot Garden. Mel's Mix calls for 1/3 compost, and every bed needs a top-up each year. With one bin you close the loop — kitchen and garden waste goes in, rich dark humus comes out.

Why compost?

  • Closes the nutrient cycle — scraps become plant food, nothing leaves the garden.
  • Free fertilizer — replaces synthetic NPK for most crops.
  • Essential for Mel's Mix — one tumbler easily refills 3–4 beds per year.
  • Improves soil structure — spongy, water-retentive, alive with microbes and worms.
  • Halves household organic waste for most gardeners.

    • Green vs. Brown (the C:N ratio)

    Good compost needs a mix of nitrogen-rich 'green' and carbon-rich 'brown' material. Rule of thumb: roughly 2–3 parts brown to 1 part green by volume. Too much green → slimy and smelly. Too much brown → dry and slow.

    Green (nitrogen-rich)

  • Kitchen scraps (peelings, cores)
  • Grass clippings, fresh leaves
  • Coffee grounds & tea bags
  • Young pulled weeds (no seeds)
  • Aged herbivore manure

    • Brown (carbon-rich)

  • Dry autumn leaves
  • Straw & hay
  • Shredded cardboard (unprinted)
  • Woody prunings (chopped)
  • Sawdust from untreated wood

    • Four methods compared

    Pick what matches your space and rhythm.

    Classic pile or wooden slat bin

    Cheapest. Good airflow, needs space (~1 m³). Takes 6–12 months. Turn 2–3× per cycle. Best if you have a quiet corner of the garden to spare.

    Tumbler

    Sealed drum you spin to aerate. Fast (2–3 months), rodent-proof, tidy. Smaller capacity. Great for balconies and small gardens.

    Worm bin (Vermicompost)

    Red wigglers turn kitchen scraps into castings — the richest compost there is. Works indoors, in a cellar, or on a balcony at 15–25 °C. No meat, dairy, citrus, or onion.

    Bokashi

    Airtight indoor bucket with EM bran. Ferments (not composts!) in 2 weeks — accepts even meat, dairy, and cooked food. Bury the result; soil finishes it in 2–4 weeks.

    Care

  • Moisture: damp like a wrung-out sponge. Too dry → add water and greens. Too wet → add browns and turn.
  • Turn every 2–4 weeks to oxygenate. A turned pile heats up and decomposes far faster than a stagnant one.
  • Chop or shred large pieces. A 2 cm branch takes 2 years, a chopped leaf 2 months.
  • Cover in heavy rain and over winter — keeps the pile from drowning in summer and retains warmth in the cold months.

    • What goes in

  • Vegetable & fruit scraps (raw)
  • Coffee grounds & tea bags (paper only)
  • Eggshells (crushed)
  • Dry leaves & straw
  • Non-diseased garden trimmings
  • Shredded cardboard (no glossy print)

    • What doesn't

  • Meat, fish, dairy
  • Cooked food with oil or salt
  • Diseased or pest-infested plants
  • Perennial weed roots (bindweed, couch grass, ground elder)
  • Treated or painted wood
  • Cat or dog waste

    • Troubleshooting

    Smells rotten or like ammonia

    Too wet or too much green. Turn the pile, add browns (leaves, cardboard), and loosen it for airflow.

    Nothing is happening

    Too dry, too brown, or pieces too big. Add water and kitchen scraps, chop oversized material.

    Attracts rats or flies

    No meat or dairy. Always cover fresh kitchen scraps with a layer of browns. Switch to a closed tumbler or worm bin if the problem persists.

    White mycelium inside

    Harmless — fungi breaking down cellulose. Turn the pile to speed things up if you want.

    When is it ready?

    Dark, crumbly, smells like forest floor. Original ingredients are no longer recognizable. Classic pile: 6–12 months. Tumbler: 2–3 months. Worm bin: ~3 months. Sift through a 10 mm mesh — anything too big goes back into the next batch.

    Using compost in your SFG

  • Mel's Mix: 1/3 compost by volume when filling a new bed.
  • Spring top-up: 1–2 cm over each bed before planting.
  • After harvest: a trowelful per square before replanting.
  • Heavy feeders (tomato, cabbage, corn): add an extra handful when planting.
  • Compost tea: soak a shovelful in a bucket of water for 24 h, dilute 1:5, use to water crops.

    • You don't need a huge compost operation for a SFG — a 1 m³ bin or a single tumbler easily covers 3–4 beds year after year.

    Compost bin cross-section

    Greens (kitchen + fresh)

    Browns (leaves, straw, cardboard)

    Finished compost

    Coarse base for airflow