Composting Worms

Use red wigglers, Eisenia fetida. Start with around half a pound for a standard household bin, feed small amounts, keep the bedding as damp as a wrung-out sponge, and the population will grow to match the food you give it.

Quick picks

#	Product	Best for	Score	Price
1	Top pickRed Wiggler Composting WormsLive red wigglers, sold by count	Stocking a worm bin	8.5★★★★★	Check price on Amazon
2	VermiHut Plus 5-Tray Worm Composter5 stacking trays with moisture and odor boards	Indoor composting, no yard	8.6★★★★★	Check price on Amazon
3	Wiggle Worm Pure Earthworm CastingsPure castings, used at low rates	Topping up a tired bed	8.8★★★★★	Check price on Amazon

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Scores are our own editorial judgment, formed from published specifications and independent sources. They are not aggregated customer ratings, and they are not the result of hands-on testing, which we do not currently do. See how we choose.

Red wigglers live in decaying organic matter at the surface -- extension guidance describes them burrowing only a few inches down. That is precisely the environment a worm bin creates, which is why they thrive in one.

Nightcrawlers and the earthworms in your yard are soil-dwelling burrowers that need deep, cool, undisturbed soil. In a shallow bin of food scraps they try to escape, and if they cannot, they die. Collecting worms from the garden to stock a bin is the single most common way a first worm bin fails.

Around half a pound suits a standard household bin. Worms can process something like half their body weight a day under good conditions, so half a pound handles a modest daily amount of scraps to begin with.

The population self-regulates. Feed more and, given space and conditions, they multiply; feed less and numbers settle back. You do not need to buy more later unless something has gone badly wrong.

Shredded newsprint -- black-and-white pages only -- or torn cardboard. Soak it and squeeze it out until it is about as damp as a wrung-out sponge, fluff it up, and fill the bottom portion of the bin. That bedding is both habitat and carbon source.

Top the bedding up as it gets consumed. A bin that is all food and no bedding goes wet and sour quickly.

Bury food under the bedding rather than leaving it on the surface. That is what keeps fruit flies away and encourages the worms to work through it.

• Temperature. They are comfortable in the range a house stays at. A garage that freezes or a shed that bakes will kill them.
• Moisture. Damp, never saturated. Too wet and they drown; too dry and they desiccate.
• Do not overfeed. Uneaten food rots, the bin goes acidic and smelly, and the worms suffer. Feed less and more often.
• Drain the liquid. Most bins have a tap. Left to accumulate, drainage floods the bottom tray.

In a stacking-tray bin, worms migrate upward toward fresh food and you lift off the finished tray beneath. In a single container, the side-to-side method works: push everything to one side, add fresh bedding and food to the empty half, and wait a couple of weeks for the worms to move across before removing the castings.

Extension guidance suggests three to five months before a bin is ready for its first harvest. After that it is continuous. For what to do with the castings, see the best compost for raised beds.