How to use a continuous-flow worm composter

Alongside the stacking-tray model, described in our guide The stacking-tray worm composter, there is a second major family of worm composters: continuous-flow models. The principle is different but just as effective, and it especially appeals to households that produce a larger volume of food scraps.

The principle: one bin, a continuous flow

Unlike the stacked-tray system, the continuous-flow worm composter is based on a single large bin, usually taller than it is wide. You add your food scraps at the top, just as with a tray model. But instead of the worms moving up from one level to the next, it's the material itself that gradually moves down: fresh scraps stay at the surface, where most of the worms gather to feed, while older, already digested material slowly sinks toward the bottom of the bin as more is added.

At the bottom of the bin, there is a grate or a set of removable bars. When the compost at the bottom is finished, you simply harvest it through this grate, without having to open or move anything else.

Key takeaways

The continuous-flow principle can be summed up in one image: the material makes its own way from top to bottom, while the worms stay concentrated near the surface, where the fresh food is.

Harvesting without disturbing the worms

This is the system's biggest strength: because composting worms naturally stay in the upper layers, close to the fresh food scraps, the finished compost harvested from the bottom of the bin contains hardly any. You get fine, ready-to-use vermicompost without having to pick out the worms one by one, as can be necessary with other harvesting methods.

The advantages of continuous flow

This system has several advantages over the tray model. Its larger capacity makes it a smart choice for a big household or a large volume of food scraps. You can harvest continuously, a little compost at a time, rather than in large batches several months apart. And since there are no trays to add or rotate, day-to-day use is simpler: you feed at the top and harvest at the bottom, with no other steps.

Key takeaways

Harvesting without disturbing the worms, feeding without levels to manage: continuous flow simplifies the routine, in exchange for a footprint that is generally more vertical than a tray model's.

What to watch out for

This format also has its own quirks worth knowing about. Its considerable height calls for a bit more vertical space than a tray model, and adding food scraps at the top can be less convenient if the bin is tall. The material can also become compacted in a large vertical volume, so it's a good idea to mix the upper layers occasionally to keep it well aerated, which is essential for the worms and microorganisms to do their job. Finally, harvesting from the bottom takes a little practice at first, until you find the right rhythm.

Trays or continuous flow: how to choose?

Tray model: several stacked bins

Continuous-flow model: one bin, one flow

Both systems work very well and rely on the same biological principle: your choice will mainly depend on the space you have, the volume of food scraps you produce, and your habits. The tray model, more modular and easier to see into, is a great fit for beginners or a medium-sized household. Continuous flow, with a smaller footprint but more height, tends to win over households with a large volume of food scraps or those who prefer harvesting regularly rather than in batches. Browse our full range of worm composters to compare the models available in both systems, and see our guide How to get your worm composter started for the next step.

Related products

Preorder

WORMgarden Worm Composter | 2 levels

1 to 3 planters with 6 growing pots per level

$233.11 €207.50

Transfarmers Worm Composter

Flower pot with worm composter

$158.21 €140.83