Interactive lesson

Wormery, step by step

Interactive lesson: from the first box to vermicompost — the right worms, size, box and outdoor bed, bedding, feeding, problems and the harvest.

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The whole lesson as text

1. The right worms

Only composting worms work in a box, not the ones from the garden.

Composting, not earthworms — A wormery takes red composting worms, Eisenia fetida and E. andrei. Leave the earthworm in the garden, where it is worth its weight in gold.
Warm, moist, dark — Worms need 15–25 °C (60–77 °F), 70–80 % moisture and darkness. Below 5 °C (41 °F) they stop, and above 30 °C (86 °F) they die.
Buy a little — One kilogram holds roughly 2,000–4,000 adult worms, with bedding and cocoons. For a household box 0.5–1 kg (1–2 lb) is enough; the worms multiply on their own.
Settling in under a light — Put the worms into the prepared bedding under a light, with the lid off, for 1–2 hours. They flee the light and burrow in by themselves. Don't feed them in the first week, or only a little.

Why: Composting worms live in the top layer of leaves and manure, breed fast and tolerate crowding. The earthworm digs deep burrows and dies in a box.

"Californian" is a trade name: these worms (tiger worms, brandlings, red wigglers) also live wild in old manure and compost heaps.
It is safer to buy a proven culture from a worm supplier than to hunt for worms in heaps.

2. How big

The size of a wormery depends on how many scraps you have.

Weigh your scraps — For one week put your kitchen scraps (no meat) on the scales. A family of four usually has 3–5 kg a week.
Twice the worms — Daily scraps × 2 = kg of worms at full capacity. For 0.5 kg a day you need 1 kg of worms, and you start with half that.
Surface — Weekly scraps × 0.2 = m² of surface. For 4 kg a week you need about 0.8 m², e.g. a box 100 × 80 cm.
Depth 25–40 cm — Keep it 25–40 cm (10–16 in) deep. Shallower dries out. Deeper packs down and has no air at the bottom.

Why: Worms work in the top 20–30 cm, so surface area matters, not depth. If you have more scraps than the worms can eat, the box gets overfed.

Surplus scraps the worms can't keep up with go to the compost heap (H03-01) or to the hens.
Worms multiply on their own, so better to start small and expand later.