Build quick composter yourself – Instructions for thermal composter

Good garden compost is not regarded as Mother Nature’s brown gold and the hobby gardener’s money box for nothing. Invisible to the human eye, an army of microorganisms in the compost heap is busy converting waste into natural fertilizer and rich humus. Depending on the size of the compost heap, this biological process can take a year or more. In a closed high-speed composter, various factors – above all heat – cause a significant acceleration of this impressive nutrient cycle. It is primarily allotment gardeners who benefit from the advantages of a thermal composter. Smart savers among them take practical instructions to hand and simply build a quick composter themselves.

Choose location

On a large plot of land, the hobby gardener usually has a whole series of hidden parking spaces for an open wooden composter, which are not visible to the viewer. In the small garden, on the other hand, there is often a lack of a hidden place for the compost heap, so that the owners with a heavy heart do without it because it disturbs the appearance. That doesn’t have to be the case, because a lockable quick composter in a subtle, dark green or gray-black design is sufficient for collecting garden and kitchen waste for tight areas. In order for the container to live up to its name by producing the desired humus and fertilizer more quickly, heat, oxygen and a little moisture are required. Accordingly, the following requirements should be met at the selected location:

Sunny to partially shaded, airy location.
Loose, unsealed soil without waterlogging.
At least 50 cm distance to the neighboring property.
Easy access to the lid and removal opening.
Unlike a conventional compost heap, a thermal composter often has a bottom. This reliably prevents infestation by mice or rats. Ventilation slots on the side or in the bottom of the container ensure the necessary air circulation. Without a sufficient amount of oxygen, putrefaction sets in, which not only significantly affects the natural process of rotting, but also brings with it the dreaded smell.

Tip: Grass pavers are an excellent base for the high-speed composter. On the one hand, these are stable enough to bear the increasing weight of the container and, on the other hand, do not allow waterlogging to occur.

Build your own quick composter

A plastic barrel or a cheaper metal barrel with a lid are ideally suited for use as a quick composter. The cover is essential, because inside the closed container, temperatures of 50 ° to 70 ° Celsius arise in the warm summer months. Thanks to this heat development, the rotting accelerates to a period of a few weeks. This speed cannot be achieved with an open compost.

Material list:

  • 1 barrel (plastic or metal) with a volume of 75 to 240 liters.
  • Maybe a piece of wire mesh.

Tool list:

  • hole drill
  • jigsaw
  • 1 flap hinge
  • 1 clasp
  • screwdrivers and screws

Instructions for the work flow

Before the fast composter is positioned in its place, it has a few air holes on the side and 2-3 slits in the bottom so that a mouse cannot cheat its way through. If you want to be on the safe side, you can also lay wire mesh on the sole inside the container. In the next step, a flap is installed near the ground, from which the finished compost is skimmed off.

Make the removal flap

  • Cut out a sufficiently large piece from the side.
  • Attach the hinges to the lower edge and the lock to the upper edge.
  • Alternatively improvise with small holes and binding wire as well as a furniture knob.

The container is filled by lifting the lid briefly. It is important to note that both covers are always closed again so that the heat that is generated cannot escape. Only the holes and slots are responsible for ventilation.

Build a quick composter from trash cans

Resourceful hobby gardeners who have a 240 liter garbage can modify it in a few simple steps to convert it into a thermal composter.

  • Remove the cover, wheels and axles and put them to one side.
  • Saw out the handle on the cover and keep it ready.
  • Saw out the middle piece together with the recess plus 3 cm.
  • Turn the garbage can over, place the cut-out lid on it and mark it.
  • Now saw out the opening approx. 2 cm smaller than the marking shows.
  • Place the cut-out piece of cover on the marking and fasten with the hinges.
  • Then attach the handle using blind rivets and washers.

The required air holes with a diameter of 15 mm are drilled into the collar edge of the upturned garbage can, which now rests on the floor. The following work step deals with the construction of the removal flap, as described above. The transformation of the garbage can into a quick composter is almost complete. Last but not least, the hobby gardener lays out a wire mesh at the intended location and places the container over it. Since there is no soil in this variant, he fills in coarse material such as brushwood or chopped material as the first layer.

Drum composter – the high-speed variant

A quick composter delivers mature humus and natural fertilizer more than twice as fast as a classic compost heap. A drum composter admittedly adds another tooth to this process. The secret lies in the interplay of heat, air, moisture and movement, because the contents are effectively mixed by simply turning. No additional repositioning and sieving is necessary. Since fully constructed drum composters require a very expensive investment, the allotment gardener would like to build this miracle container himself.

Material list:

  • 1 metal barrel with a volume of 75 to 240 liters.
  • 1 PVC pipe, 1.25 m long, 50 mm thick.
  • Alternatively 1 galvanized pipe of the same size.
  • 4 wooden strips or beams, at least 40 mm x 70 mm.
  • 2 square timbers
  • 1 angle plate


  • hole drill
  • folding rule
  • Hammer and nails
  • screwdrivers and screws
  • hacksaw
  • Flap hinge and lock

Drill a hole exactly in the middle of the top and bottom that corresponds to the diameter of the pipe. Then push the pipe through. Drill a few air holes in the upper and lower third of the container, leaving the middle area untouched for the time being. The prepared drum composter is now set aside to build the associated wooden frame. For this purpose, 2 of the wooden strips are screwed together and connected by the square timbers so that a stable foot is created, similar to a sawhorse. Now you can hang the barrel in the frame, using the tube as a pivot. An opening is now missing through which the drum composter can be charged or the ripe humus can be removed. In contrast to the rapid composter, the filling and removal flap is in this case placed on the side of the container, namely where no air holes have been drilled.

Basically, the drum composter is now ready for use. The effectiveness of the apparatus is, however, significantly increased if a shovel fixed there supports the mixing process inside the container. For this purpose, an angle plate is screwed to the wall opposite the opening.

Note: The darker the color of the drum composter, the more intense the solar radiation. It is therefore advisable to paint a barrel that is too light in color.
Over time, the barrel increases in weight, making it increasingly difficult to turn. If you don’t feel like struggling with it, simply add a rotary handle:

  • Drill an approx. 2.5 cm hole through one end of the rotary tube.
  • Push a round, 60 cm long metal rod of the same thickness through it.

A hose insulation put on each end ensures that the handle fits better in the hand.

Thermal composter with thermal insulation

Experience has shown that a volume of 240 liters, such as barrels and garbage cans, is not sufficient in medium-sized gardens. A larger volume, on the other hand, heats up much more slowly, even if the container has a cover. The solution to the problem lies in the construction of a thermocomposter that stores the heat thanks to an insulating layer of air. The secret lies in the use of insulation panels, as they are also used for facade insulation.

Material for an 800 liter composter:

  • Plastic insulation panels for outdoors
  • Insulation board 3 m x 1.50 m as a cover
  • Perforated base with 10 mm x 10 mm holes.
  • 1 plastic handle
  • 8 angle profiles 50x50x3 mm, 750 mm long.
  • 2 hinges for the lid.
  • 2 hinges and 1 lock for the removal flap.
  • Stainless screws.

The number of panels depends on the preferred profile size. They can be easily cut to size using fine-toothed hand or table saws.

The insulation profiles are connected to one another in such a way that 4 side walls are created. Then these side parts are screwed to the angle profiles. An angle profile from the outside and one from the inside is fixed with continuous screws. This is the only way to ensure that the plastic walls withstand even greater loads and do not tear. In the rows of grooves in the panels there are longitudinal grooves with pre-punched screw holes so that the walls can be attached to the perforated base. Blind rivets fix the handle on the lid, while the cover itself is attached by the hinges. It makes sense to additionally secure the lid to the side wall with a pull cord so that it doesn’t flip over every time it is opened. The removal flap in the lower container area should of course also not be missing.

Note: A perforated floor can be dispensed with if instead a wire mesh is laid out under the thermal composter to ward off pests.

Pre-assembled composter

The specialist trade offers a range of high-speed and thermal composters that are disassembled and only need to be fully assembled. The following models consistently achieved good ratings in tests.
Here we show you the best composters for your garden.

Quick composters are a great way to get the ugly compost heap out of sight in the small garden. At the same time, they quickly produce rich humus and free fertilizer. A thermal composter made of insulated material also increases the efficiency of the nutrient cycle through higher temperatures inside. Both models are available in stores, but can be built yourself with a little manual skill. This not only saves money, but also increases flexibility in terms of size and area of ​​application. In this way, the beneficial use of rich compost is within reach even in the smallest garden.

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