A compost tumber is a rotating drum with a hatch or lid which is opened to empty your composting materials inside. The lid is then closed and you turn a handle which rotates the drum around. This mixes the contents of the drum and keeps the heat and gasses trapped inside. This results in a faster composting process, as the partially decomposed material mixes with the fresh material in a heated environment. The drum can be turned once a week or each time you add new material.
There are many types of compost system. Traditionally, composing was done in heaps or pits, but over time compost bins came to be the norm. They are the typically the least expensive option, being little more than an open-bottomed box set on the ground. These bins have several disadvantages:
- Heat is easily dissipated which slows the compost process
- It’s difficult to turn the compost using a pitchfork or shovel
- Rodents and other small animals can burrow under the sides and access the composting materials
More recently developed, compost tumblers are fully sealed containers that are a much more efficient composting system; these containers are set up quick composting and spare the gardener the more arduous task of manually turning the compost to aerate and mix the organic matter.
They have many advantages, most notably that their sleek design and clean operation makes them highly suitable for urban or suburban properties as the waste – and smell – are contained within the closed tumbler drum.
It’s difficult to say when the first tumblers were used. In the 1970s when organic gardening began to grow in popularity, a few innovative gardeners offered plans for barrels, compost rollers, and other schemes for containing and turning compost. And though there are still a variety of building plans available for making your own compost tumbler, commercial tumblers – often made from recycled plastics – have also been available for decades now, with different options and designs appearing over the years.
How do compost tumblers work?
It’s really quite simple. You load the tumbler with organic matter – the green and brown waste from your yard and kitchen. When full they will require some time to work, as they heat up the composting materials and speed up the decomposition process.
The organic materials are broken down, as in the compost heap method, by microbes and other living organisms fueled by oxygen. To optimize the process, the tumbler should be turned two or three times a week, mixing the microbes with the organic material while infusing fresh supplies of oxygen.
Manually turning a compost pile mixes the organic materials and the organisms they contain with heat-producing oxygen and is the traditional method of composting. A tumbler does this more simply and easily; by turning the tumbler, the organic materials are mixed and infused with fresh oxygen.
The tumbler keeps the materials and heat contained, and in a month or so – when a check reveals the compost is complete – it’s time to spread the results.
Different types of compost tumbler
There are currently several designs of compost tumbler and each has features designed to improve the composting process and experience. Commercially-sold tumblers are typically horizontal but can also be vertical.
Compost tumblers vary in size from small barrels designed for back porch use to larger bins capable of holding bushels of yard waste.
While the simplest designs are basically rotating barrels, more sophisticated models have handles for turning the tumbler and may even use piping to bring oxygen into the center of the barrel and paddles inside to help mix and aerate the composting materials.
Sealed drum compost tumblers
The most basic design is a spinning drum or barrel that is either mounted on a raised axle or set on a base with rollers. The interior of the drum is usually designed to flip the composting materials as the drum turns; otherwise the organic matter would simply slosh around while the drum rotates without being mixed or turned.
The raised models enable the gardener to place a wheelbarrow or bucket directly under the drum so that finished compost is easily transferred for moving to the garden beds while tumblers that are set on a base with rollers can also be rolled off the base, to wherever you plan to empty the compost; the base may also serve as a ‘compost tea’ maker, by collecting liquid drain-off from the composting materials which can be used as a liquid or spray fertilizer.
Though a sealed drum tumbler is the simplest design, with fewer moving parts that may malfunction, it is slightly slower to compost than aerated models.
Aerated drum compost tumblers
Aerated composters are designed to deliver more air to the composting materials, which speeds the composting process and allows gardeners to cycle more batches through their composter. A small aerated drum can produce just as much compost over a year than a much larger sealed drum.
The simplest designs have a pattern of holes drilled through the end of the composter. The downside of this design is that the holes may be become blocked or filled with gunk and need to be cleared; a thin stick works quite well.
Other aerated models have hollow spikes radiating inwards; these also break up the composting materials as the drum spins; however, larger plant clipping may get stuck between the spikes, so be sure to chop up any long clippings or stems before adding them to the drum.
Generally, the simplest aeration designs work best as there are fewer parts that may break or malfunction.
Dual-bin compost tumblers
The dual-bin design sets two small bins side-by-side in a single rotating drum; the thickly-insulated compartments conserve the heat generated by the decaying organic matter and greatly speed up the composting process.
A screened opening on either end of the drum provides aeration to each chamber. Some larger models also have a gear-driven crank handle to make turning the drum easier.
While older models of dual-bin composters had a single access door which covered both chambers, new models tend to have two separate doors. This allows the gardener to rotate the drum directly over a wheelbarrow or bucket when each batch is ready, and to tip the finished compost out easily.
Though a dual-bin tumbler greatly speeds up the composting process and allows – if timed properly – batches to be ready every two to three weeks, they can be considerably more expensive than the basic, single-bin models. And while the dual-door design makes it easier to access the finished compost, the quality of the door hinges is paramount as cheap hinges will greatly compromise the functionality of the compost tumbler.