Composters have the task of producing valuable fertiliser from waste materials and with the help of soil organisms. An open composter supports this process by providing the necessary oxygen supply. On the other hand, the closed composter creates a much warmer compost environment. In addition to these two factors, there are many other things that need to be considered.
To give you an overview, we have listed the advantages and disadvantages of the respective designs of open and closed composters. Our composter test 2021 aims to help you with this purchase decision and to answer any questions you may have.
- 1 Weekly newsletter with the best personal finance tips
- 2 The most important facts
- 3 Weekly newsletter with the best personal finance tips
- 4 The best composter: Our picks
- 5 Buying and evaluation criteria for composters
- 6 Guide: Frequently asked questions about composters answered in detail
- 6.1 What is a composter?
- 6.2 How does a composter work?
- 6.3 Who is a composter suitable for?
- 6.4 What does a composter cost?
- 6.5 What types of composters are there and which is the right one for you?
- 6.6 What alternatives are there to the composter?
- 6.7 How can I beautify the composter?
- 6.8 How do I restack a composter?
- 6.9 How do I fill a composter?
- 6.10 Where should I put the composter?
The most important facts
- The composter provides optimal conditions for soil organisms to produce reusable fertiliser from garden and kitchen waste. Composting is therefore a more environmentally friendly alternative than going to the organic waste bin.
- A distinction is mainly made between open and closed composters. The latter can be further differentiated into rotating/movable or stationary.
- Open composters are usually larger, nicer and cheaper. Closed composters, on the other hand, compost faster, are more robust and less costly.
The best composter: Our picks
Buying and evaluation criteria for composters
Next, we will show you which aspects you can use to decide on a suitable composter.
Based on these criteria, you can compare composters with each other:
In the following paragraphs we will explain what you need to consider for the individual criteria.
Base & lid
In general, the composter should be placed on open ground if possible. This prevents waterlogging. Otherwise the water will collect and mould will set in. This also allows animals and microorganisms to enter the composter and decompose the compost.
If you want a composter despite solid ground, you can add soil organisms such as earthworms yourself or just buy a worm composter or Bokashi bucket directly. You can find out more about this in the guide under "What are the alternatives to composters?
If you choose a completely closed composter, you should water it on very hot days, otherwise it will dry out.
Frequent rainfall can make an open composter too wet. In this case, a mulch fleece would be advisable, which keeps the moisture at a reasonable level.
Depending on the type of composter, the composting process can be accelerated. Fast composters are particularly popular with amateur gardeners, as they take up very little space. Furthermore, they need less material to reach the right heat in contrast to open ones.
The thermal composter belongs to the subgroup of quick composters. This is able to store heat consistently due to its double-walled insulating construction.
Another composter variant would be the drum composter. Here, the compost material is placed in a barrel-like structure and turned by a crank or by hand. The material inside is heated and aerated.
In addition to the composter itself, compost accelerators help with decomposition. They contain the nutrients that the soil organisms need for the decomposition process. Otherwise, the general rule is that the smaller the waste, the faster it decomposes.
Material, colour & shape
Basically, open composters are usually made of wooden pallets. Another type is expanded metal, which usually contains stainless steel or aluminium and has a grid-like structure. Wood in particular looks aesthetically better in the garden. On the other hand, it is more exposed to the weathering process than a closed composter would be.
Closed composters are usually made of plastic or metal. Since plastic is relatively flexible, it can lose its original shape over time. Metal is more durable, but even powder-coated metal can rust over time. Galvanised is more suitable in this case. They are often available in dark green, black and rarely brown, as this promotes the warming process and visually matches the garden.
The shape of the composter, i.e. whether it is round or square, is basically not very important. The only important thing is that there is enough space.
Rearrangement & chamber systems
Turning over the soil is a crucial part of composting. In this process, the bottom soil, which is now older, is moved upwards so that the new material has access to warmth and microorganisms. The whole compost receives a renewed supply of oxygen.
The process is supported by the choice of composter. A thermal composter, for example, has a flap underneath where you can directly access the already composted material.
If you would rather not stratify at all or with minimal effort, a rolling composter would be for you. As the name suggests, it is rolled from one place to another with the help of its ball shape. The disadvantage is that it is not connected to the ground. The same applies to the drum composter mentioned in the "Speed" section.
With open composters, it is a good idea to add several boxes right next to each other in order to layer the compost from one container to the other.
Vermin & Odour
Many problems that arise during composting have more to do with the care itself than with the choice of composter.
If the right mix of oxygen, moisture and heat is present, no foul odour should develop. This balance can be disturbed if too much raw material is placed on top of each other. In this case, a larger composter is recommended.
Tip: If the composter is too wet, it is advisable to add dry branches.
Openings in the composter also often attract unusual garden inhabitants. In the case of large rodents such as rats and mice, an additional floor grid can prevent them from entering. Smaller animals such as ants, mosquitoes and flies are included in small numbers. In excess, however, it is advisable to sprinkle lime or gravel. This prevents rotting, which attracts the animals in the first place.
Most composters are categorised according to their capacity in litres.
- Composters with 250L-400L belong to the small sizes for composters in the garden and are mostly for small families, couples or individuals.
- In the medium range are those between 400L-600L. Thermal composters are particularly suitable there.
- The largest ones, up to 900L, are only suitable for very large households, when shared with neighbours or for those who keep several beds. In this size they usually come in open form.
If you are unsure about the size, especially because of a lot of leaves, you should buy a compost silo made of galvanised wire in addition to the composter for household waste. Of course, you can also collect it in the classic way as a heap.
As a general rule, it is better to buy 2 smaller composters instead of one large one. While one is being filled, the other can take a break.
Guide: Frequently asked questions about composters answered in detail
The guide contains essential questions on the subject of composters. It explains briefly and concisely what is helpful about composters.
What is a composter?
Nowadays, a composter is used by both hobby gardeners and waste management. For example, compost can be produced from kitchen and garden waste.
How does a composter work?
Besides, the oxygen-nitrogen ratio must be in balance. The same applies to the moisture content.
If this is observed, the composting cycle takes place in three phases:
- At first, mostly mesophilic organisms (small animals with preferences for medium temperatures) participate. They break up the compost into finer material over a period of a few days.
- In the second phase, they are replaced by heat-loving organisms. The temperatures can become so high that even actually helpful helpers die off. This is counteracted by regrouping. Fresh air and new materials for decomposition are brought in. This phase lasts longer than the first.
- The last phase lasts the longest (several months). There, the temperatures drop continuously and mesophiles again take over the processing of what is left.
These phases are gone through to create compost from waste.
Who is a composter suitable for?
Even without a garden, a composter is suitable, because houseplants also enjoy the nutrients. In addition to the potential fertiliser, the composter is a more environmentally friendly alternative than the organic waste bin.
What does a composter cost?
Simple composters for smaller gardens and households can be found for around 20 pounds. These mainly include wire and cheap wooden composters. The majority are more in the range of 40 to 70 pounds.
What types of composters are there and which is the right one for you?
|Types of composters||advantages||disadvantages|
|Open composter||larger, more accessible||weathers faster, free access for animals|
|Closed composter||rodent safe, faster||more expensive, unnatural|
In this case, open composters refer to those made of wood, while closed composters mainly refer to thermal composters.
Depending on the amount of compost, space and type as well as personal preferences, there are different advantages and disadvantages. To help you decide which model to choose, the next section lists the most important points of both composters.
What alternatives are there to the composter?
Besides the typical composter, there are other alternatives. The two alternatives are:
- Bokashi bucket: Bokashi is the name for a method similar to composting. In the bokashi bucket, the raw materials are fermented, i.e. primarily converted into an acid mass without the inclusion of oxygen. Kobashi compost is only applied directly to beds after the pH value has been lowered.
- Worm composter: Another indoor alternative for the balcony or flat is a worm bin. Compared to the garden, more soil organisms live in one space. To preserve this diversity, acidic fruit and chemically treated food in general should be avoided.
The two alternatives can also be used for disposal and for reuse.
How can I beautify the composter?
- Pumpkins or courgettes in already decomposed compost
Stone walls are not recommended as they get in the way when rearranging and are more difficult to remove if the composter is enlarged.
How do I restack a composter?
- Make room: If you only have one chamber, move all the compost from one side to the other on top for the first time. If you have two or even three chambers this is not necessary
- Sieving: Next, throw the compost through a large sieve using a shovel or fork. What does not fit through (usually branches, large stones as well as coarser compost) is used again later or removed.
- Replenish: The humus can now be used. Meanwhile, the composter is filled up with new materials.
In order to achieve the best possible turnaround of your composter, you should go through the previous steps.
How do I fill a composter?
Not all materials may end up in the compost without further ado. These include:
- Dairy products
- Pesticide treated or diseased plants
- Cat litter
- cooked food scraps
- Weeds (if not yet dried out and seed bearers)
It is important to maintain the carbon (brown) to nitrogen (green) ratio of 20:1 on the compost. You can see what belongs to which category in the table:
|carbon||old hay, leaves, coffee grounds, cardboard, wood shavings|
|nitrogen||vegetables, fruits, grass, flowers, algae|
Products such as eggshells, paper, hair or nutshells should only end up in the compost in very small quantities. If you are unsure, it is better to be safe than sorry!
Where should I put the composter?
When placing at the end of the property, maintain sufficient distance from neighbours. Remember that the further away the composter is, the more you have to walk every day. This can be inconvenient, especially in large gardens.
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