Hemp mat / XXL moisture pad

Like our pre-cut mats, the XXL mat goes on top as a cover over fresh food scraps: it keeps the surface moist, keeps fruit flies out, and gives the worms a sheltered spot to breed. Because it's so large, it can also cover a backyard compost bin.

It isn't essential: cardboard or an old cotton cloth does the same job. In winter, a piece laid over the lid of an in-ground worm composter such as the WORMacotta also helps protect it from frost.

All our tips: Which accessories does your worm bin need?

Yes, worms love the XXL mat, whether in a large worm composter or a backyard composter. Cut to fit your model, the hemp keeps the surface moist and protects the worms from the cold and from temperature swings: they come up to feed under the mat and break down food scraps faster.

Worms love to lay their eggs in it: you'll find cocoons about an eighth of an inch (a few millimeters) long, which turn from pearly white to yellow and then brown. Natural and biodegradable, the XXL mat breaks down over time and can be eaten by the worms.

Cut the XXL mat sheet to the shape of your bin using heavy-duty scissors. Then lay the piece flat on top of the worms and the freshest food scraps, under the lid; new additions always go underneath it.

Like all our mats, it goes in dry: the moisture from the food scraps is enough to soak it through. From time to time, you can spray it with diluted WORMboost to stimulate the worms.

In a stacking-tray worm composter, the piece you cut from the XXL mat follows the active tray: when you add a tray, move the mat up into the top one. A single mat is all you need.

In a backyard composter without trays, lay it directly on the freshest layer of scraps, under the lid. Store the rest of the sheet in a dry place at a moderate temperature for future replacements.

All our tips: How does a stacking-tray worm composter work?

Each piece cut from the XXL mat lasts 2 to 3 months on average in a worm composter: the worms nibble away at the hemp until it's full of holes, which is normal for a natural material.

Replacing it is easy: cut a new piece from the sheet and lay it on top of the old one. Don't remove the old piece, since it may contain cocoons. Any leftover bits that are too thick can be crumbled into the food scraps, where they count as a carbon-rich addition. With 13 sq ft (1.21 m²) of hemp, a single XXL mat gives you plenty of replacements.