Vermicompost at Home (Kenchua Khad): Worms, Bin, Heat, Harvest

The earthworms you dig up in a garden bed are the wrong worms for a bin. Vermicompost at home needs composting worms, usually red wigglers, a two-bucket bin with damp bedding, chopped kitchen scraps in small amounts, and one thing our summers make hard: keeping the bin below about 30°C. Do that, and in two to three months you’ll have kenchua khad (worm compost), the fine, dark castings gardeners prize. It’s more fiddly than plain compost, and this guide is honest about where it goes wrong.

Which worms make vermicompost, and where to buy them

Ordinary garden earthworms dig deep tunnels and live in soil. Put them in a bucket of peels and they sulk, escape or die. Composting worms are different. They live in the top layer of rotting leaves and dung, eat almost their body weight’s worth of soft food over a few days when conditions are good, and breed well in a crowded bin.

• Red wigglers (Eisenia fetida): the classic home worm. Thin, reddish, with faint stripes. Happy in mild weather, stressed in serious heat.
• African nightcrawlers (Eudrilus eugeniae): bigger, greyish-purple, and widely used on vermicompost farms in Pakistan and India because they cope better with warmth. They dislike cold, though, and slow right down in a north Indian or Punjab winter.
• Indian blue worms (Perionyx excavatus): also used locally, fast workers, but more likely to wander out of a bin.

Buy them from a nursery, an agriculture university, a local vermicompost farm, or an online seller who ships in damp bedding. Healthy worms are moist, move quickly when touched and are mixed with dark, damp bedding. Skip a batch that’s dry, pale or smells rotten.

How to make vermicompost at home from kitchen waste: the two-bucket bin

1. Take two 20 litre buckets with one lid. Drill 15 to 20 holes of 3 to 5 mm in the base of the first (inner) bucket, and a row of the same holes around its top 5 cm for air. Drill a few tiny holes in the lid.
2. Put a brick or an upturned small tub in the second (outer) bucket, then stand the inner bucket on it so there’s a gap of about 5 to 8 cm at the bottom to catch liquid.
3. Make the bedding: tear plain cardboard and newspaper into strips, soak them in water for 10 minutes, then squeeze until only a few drops come out. Mix with a few handfuls of coco peat or dry leaves and one handful of garden soil for grit.
4. Fill the inner bucket about halfway with this loose, damp bedding. Let it sit for a day.
5. Tip the worms gently on top with the bedding they came in. Leave the lid off with a light on above the bin for the first night; worms avoid light, so they’ll burrow down instead of exploring.
6. Wait 2 to 3 days, then give the first feed: about 1 cup of chopped scraps, buried under the bedding in one corner.
7. Feed the next time only when most of the last lot has gone, rotating corners. Increase slowly as the worms keep up.
8. Lay a sheet of damp newspaper or a piece of wet jute sack on top of the bedding to keep moisture in, then close the lid.

The liquid that drains into the outer bucket isn’t the “worm tea” sold online; it’s mostly water that ran through rotting food. Pour it off weekly, dilute 1 cup in about 10 cups of water and use it on flower pots, or tip it down the drain. Never leave it standing, because standing water breeds mosquitoes, including the dengue mosquito (see our monsoon mosquito guide).

What to feed worms, and what they can’t handle

Worms have no teeth. They eat food that bacteria have already started to soften, which is why small, soft, chopped pieces disappear in days while a whole cabbage stalk can sit untouched for weeks.

Good food: vegetable peels, lauki and tori skins, cucumber ends, banana and papaya peels, melon rinds, spent tea leaves (rinsed), coffee grounds, crushed eggshells for grit, torn cardboard and egg trays.

Only in small amounts: onion, garlic, citrus peel and chillies. A little is fine; bulk makes the bin acidic or harsh and worms try to leave.

Keep out: oil, fried food, salty or spicy leftovers, dairy, meat, bones, cooked food in quantity, and fresh cow dung (it heats up as it rots and can cook the worms; only old, dry gobar is safe). The general list is in what not to put in compost at home.

The most common beginner mistake is kindness. Too much food. Whatever the worms can’t get through in a few days sits there rotting, warming the bin, starting to smell and pulling in fruit flies from the whole building, so if last week’s scraps are still visible when you lift the sack, skip a feed.

Did you know?

Worms have no lungs; they breathe through their moist skin, which is why a dry bin kills them and a waterlogged one drowns them. They have no eyes either, but their skin senses light, so they head away from it. And each worm is both male and female, yet two worms still pair up to mate, and each leaves tiny lemon-shaped cocoons that hatch into a few baby worms.

Keeping worms alive in 45°C heat and in monsoon

Heat kills more home worm bins than anything else. Composting worms are happiest between 15 and 30°C, get stressed above that and can die around 35°C and up, and a bucket on a sunny balcony in June is much hotter than the air.

• Keep the bin indoors or in the deepest shade you have from April to September. A cool stairwell or bathroom corner works.
• Drape a wet jute sack (bori) over the bin and keep it damp; the drying water cools it, the same way a matka cools water.
• On heatwave days, put a frozen plastic water bottle in one corner of the bin.
• Feed less in peak heat. Rotting food adds warmth.
• In monsoon, the danger flips to water. Add extra dry shredded cardboard, keep the bin under cover and check the drain holes aren’t blocked.
• In winter, move the bin somewhere sheltered; below about 10°C worms nearly stop eating.

Vermicompost ready in how many days, and how to harvest

In a home bin, about 2 to 3 months after you start, the bedding and food will have turned into dark, fine castings that look like wet coffee grounds and smell of earth. Commercial beds in warm weather finish faster, often in around 45 to 60 days, because they’re bigger and run on steady feed.

The side-shift method (easiest)

Stop feeding one half of the bin and put all food in the other half for 2 to 3 weeks. Most worms move over to the food. Scoop the finished castings from the empty side, pick out any worms you see and return them.

The light method (faster, messier)

Tip the bin onto a plastic sheet in bright shade, not direct sun, and shape it into small cones. Worms dive. Every 15 to 20 minutes, scrape the top of each cone into a bucket. After an hour you’ll have a pile of castings and a knot of worms at the bottom to put back into fresh bedding.

Let the castings rest in a bucket for a week, slightly damp. They keep for several months in a covered bucket with some air, in the shade. How much to mix into pots (use about half as much as ordinary compost) is in compost ready in how many days and how to use it.

Myth: cut a worm in half and you get two worms

No. If a worm is cut near the tail, the front half, which holds its vital organs, can sometimes survive and regrow a short tail. The back half dies. So handle them gently when harvesting, and never chop them to “multiply” a bin.

The other common worry, “does vermicompost smell?”, has a simpler answer: a healthy worm bin smells like a forest floor. A bad smell means too much food, too much water or something like oil went in. Stop feeding, add dry bedding, and it clears in a few days. If you’d rather not look after live animals at all, plain bucket or matka compost is more forgiving and makes good compost too, just more slowly.

Vermicompost at home: your questions

For more ways to put kitchen scraps to use, see Zero-Waste Kitchen.