Compost – everything you need to know about the elixir of the gardening world

Setting up your own compost heap in your garden is practical. It takes very little effort, you save money, reduce waste, give your fruit and vegetables a healthy place to grow and do your bit for the environment.

We’ve compiled a handy guide with all the information you need to set up a compost heap, fill it correctly and use the compost soil.

1. Whether they’re good or bad, practical or cumbersome – we provide you with the most important facts about different composters.

A closed compost tumbler stands in front of a hedge in a garden.
A compost tumbler takes up little space and supports good composting.

1.1 Which composter is the best?

No matter how much space you have – the right composter for you is out there. One important factor is where you live. If you live in an apartment in the city that doesn’t have access to a garden, but does have a large balcony, then a worm composting bin could be the right choice for recycling kitchen waste. Space- and time-saving rapid or hot composters are recommended for small gardens. Compost tumblers are also becoming more popular, especially if you don’t have much space to spare. If you have a rather large garden, then you’ll be good to go with a traditional multi-stage composter. However, you’ll also have to bear in mind that the quantity of waste you produce also plays a role in finding the perfect composter for you. If you just have kitchen waste, then it will be difficult to keep an entire compost heap going. That’s why we recommend a worm composting bin or a small rapid or hot composter for smaller quantities of waste. Normal-sized and large composters are better suited to medium quantities of waste. If you’re hoping to compost quite a lot of material, then you should build or buy a multi-stage system

1.2 Why is composting a good idea?

To reduce your waste. What’s more, high-quality compost maintains the balance in the soil. It improves soil fertility, increases its water retaining capacity and allows flowers, fruit and vegetables to grow and flourish in nourishing conditions.

1.3 What are the advantages offered by different composters? What are the disadvantages?

If you pay a visit to your local DIY store, then you’ll quickly realise how many options for composters there are out there. From metal grids, to wooden planks, compost bins, plastic and tumblers – all varieties have their advantages and disadvantages. This is the case even for luxury all-in-one composters. Hot composters made from plastic may not look very pretty, but they are also available in smaller sizes. They are also highly functional, as optimised temperature development within the composter means that the compost matures a lot faster. The compost tumbler offers similar advantages. In no other model is hot composting as fast as in this design. As well as this, unwelcome visitors like rats and mice won’t be able to make themselves at home here. Composters made from metal or zinc are a bit more expensive, but they are also more durable and robust. The most affordable version is most definitely the wooden composter. You can even build one yourself if you’re into DIY. The problem with this model is that it rots after four to five years. What’s important to note is that all models will make your waste into nourishing humus. That means it’s up to you which version you go for.

2. How to correctly plan and set up your compost heap.

Organic waste – made up of eggshells, vegetable waste, leaves and earth – lies in an open compost bin
You’ll have to bear a few things in mind when setting up your compost heap. This is the only way you’ll guarantee that your organic waste transforms into rich humus.

2.1 Where’s the best place to set up my compost heap?

If you observe a few ironclad rules when planning your compost heap, then you’ll soon be able to look forward to very healthy soil in just a few months. For example, a compost heap should never be placed in water.

Ideally, it should be one cubic metre in size and placed neither in the direct sunlight nor in the complete shadows. In the semi-shade, such as beneath a tree or canopy, is perfect. This will prevent it from either putrefying or drying out. It should be sheltered from the wind – but not too much. That’s because in the five to six months a compost heap needs to mature, it requires fresh air and has to emit carbon dioxide. You should know in advance that your compost heap will never look particularly attractive.

Moreover, we recommend not putting the compost heap too close to your house or your neighbour’s property. Once you’ve gotten the hang of composting, then you’ll definitely put more material in your compost heap. That’s why you should bear in mind when you’re first setting it up that you will probably need to turn the compost heap later on. 

2.2 Can a compost heap be placed on concrete slabs?

A traditional compost heap should not be placed on plastic, stone slabs, concrete or asphalt. For the best possible decomposition, it is essential that earthworms as well as other critters and microorganisms are able to work their way through the heap from below. This will speed up the entire process in the compost heap. It’s only ready-to-use solutions – like models that can be used on balconies – that don’t need to have direct contact with the soil.

2.3 When is the best time to set up a compost heap?

A compost heap is most efficient when it is set up in the spring. This is when worms and other organisms are at their most productive – decomposition will be complete after just six months and your humus will be ready to use. It will take a bit longer if you start layering in the autumn. Then it can take up to twelve months for the humus to become usable as fertiliser for your garden or balcony plants.

2.4 Can you also build your own compost bin?

Of course, you can also build your own composter. All you need are suitable materials like timber or metal rods, a saw, screws, a cordless drill and a bit of time. For the best possible outcome, you should build a DIY composter based on the three-stage principle. Here, each of the three compost heaps – undergoing a different stage of decomposition – is placed beside the other.

3. All about what’s allowed in the compost – and what isn’t.

Different types of waste from the kitchen and garden lie in a compost heap. A second compost heap to the right is still empty.
You’ll have achieved the perfect compost heap when everything has been layered correctly and only things that belong in the compost are put there.

3.1 How do I compost correctly?

Variety is considered to be very important when filling your compost heap. A colourful mixture is best, while too much of one component is less than ideal. When everything has been layered correctly, then it’s time to get composting! Maintaining a temperature of up to 60 degrees Celsius within the heap is essential, as this helps to eliminate any harmful germs. But you also need to make sure that the compost doesn’t get too warm. Otherwise it will tip over and the good compost components will be destroyed. It’s also recommended that you mix some of the humus you produce under the material in the compost heap. This will help to distribute tiny composting creatures and allow them to get to work immediately.

3.2 What belongs in the compost

The majority of household and garden waste is suitable for the compost heap. Eggshells, coffee filters and fruit and vegetable waste can be thrown into the compost heap as well as lawn cuttings, branches, straw and leaves. However, you should chop up large pieces of organic waste before you throw them in.

3.3 What doesn’t belong in the compost

Diseased plants, non-plant-based kitchen waste like meat and fish scraps, bones, citrus fruits and cat litter do not belong in the compost heap – never mind glass, plastics, metal or ash. And even though they may smell similar, nappies do not belong in the compost.

4. All about composting.

A metal container with the inscription ‘Compost’ has been placed on a kitchen surface. A person is putting vegetable peelings into the container.
Kitchen waste serves as the perfect basis for composting.

4.1 How long does composting take?

When the compost heap has been set up, then it’s time to let nature take its course. We recommend completely re-layering the compost heap after three months. This will ventilate the heap and reduce its volume. The compost will be ready to use after six months – if it was set up in the spring, that is. Perhaps you’re asking yourself how you’ll know when the process is complete. Well, you’ll usually smell it. If your garden smells like a forest floor, then you can look forward to using fresh and natural humus for your plants.

4.2 How do I correctly layer a compost heap?

Producing good compost isn’t just about simply throwing all of your waste into a heap. Striking a good balance between dry and moist layers is the be-all and end-all of composting. If you want high-quality compost, then you should layer your waste in such a way that it never gets waterlogged, causing decomposition to become putrefaction. That’s why you’re best off putting a 20-cm-thick layer of grass clippings and wood chippings at the base of the compost heap. You can also include withered flowers, wood shavings, straw or coarse, earthy plant remains.

Your next step should be to place a 5-cm-thick layer consisting of garden soil or humus in the compost heap. The creatures living in this material are essential for the further decomposition process.

Now it’s time to sort out the other layers. Always remember to properly mix coarse material with fine material. Blend low-nitrogen and high-nitrogen as well as dry and moist materials together to create the perfect mixture. A layer of well-used earth from flowerpots and tubs can also be incorporated.

A thin layer made from lawn cuttings and garden soil can be used as a natural cover for the compost heap.

4.3 How can I accelerate the composting process?

If you’ve arrived a little too late to composting for the next gardening season or simply can’t wait to make your own nourishing compost for your plants from garden and kitchen waste, then there are a few ways in which you can help the process along. But be warned – you’ll really only get the best results if you let your compost heap mature in its own time. There are a few different options out there for people who would like to accelerate the process of natural decomposition to get their hands on nourishing fertiliser made from household waste ASAP. For example, you can use a compost accelerator if you want to give the microorganisms in the heap a little push. Simply sprinkle the compost accelerator onto the waste. Alongside guano, horn meal and other organic fertilisers, this can also contain calcified seaweed and rock flour, depending on the manufacturer. Adding a mixture of different herbs like camomile, dandelion and nettles can also be beneficial.

4.4 How important is moisture for the compost heap?

Your compost heap won’t be able to function with too much or too little moisture. That’s why maintaining the right moisture level is particularly important. Without moisture, the organisms in the compost heap will dry out and the entire process in the heap will grind to a halt. If the compost is too wet, then not enough air will get into it and it will begin to rot. You can give it a little boost by protecting your compost heap from above and regularly watering it with a watering can. You can tell whether the inside of the compost heap has a good moisture level if it feels like a squeezed-out sponge.

4.5 What are the advantages of implementing a compost?

By turning your compost heap, you can prevent many things that would prematurely stop the decomposition process and result in the soil you’ve produced becoming useless. Decomposition stops, for example, if there is too much moisture in the compost heap, the material doesn’t get enough oxygen or fungus spreads through it. Turning the compost heap gets it moving, circulates air, improves drainage and distributes heat. All you need is a shovel or pitchfork, a sieve, some space beside the compost heap and some time to turn the pile.

5. All about using your compost.

Green plants are growing in a flowerpot. A hand shovel, hand rake and garden trowel are leaning against the flowerpot.
Humus is perfect for growing fruit and vegetables.

5.1 How do I use compost correctly?

Fresh compost equals flower power – whether that’s in your garden, on your balcony or on your patio. You can use it for flowers and shrubs as well as fruit and vegetable plants. Plants that grow in peat soil like rhododendrons and azaleas, however, cannot tolerate compost.

5.2 How much compost should different plants get?

A 50:50 mix of garden earth or sand and compost is recommended for flowerpots. For ornamental shrubs, simply apply a three-centimetre layer of compost and gently mix it with the existing garden soil. Bulbs, cuttings and seedings of most fruit and vegetable varieties feel perfectly at home in a mixture of compost and garden earth.

5.3 How do I use fresh compost when planting in the spring?

Plants that have high nutrient requirements like courgettes, pumpkins, potatoes, cabbages and tomatoes will get the most out of compost fertiliser. These require up to six litres of mature compost per square metre. A maximum of three litres per square meter are needed for plants with medium nutritional requirements like lettuce, strawberries, onions, spinach, radishes and kohlrabi. Vegetables that do not have high nutritional requirements should be fed a maximum of one litre of compost. These include herbs, radishes, lamb’s lettuce, peas and beans, for example.

Something that’s rather widespread but is not recommended is adding calcium cyanamide to the heap. While it does boost the nitrogen content of the humus, it is harmful to many small creatures who play an important role in the decomposition process.

In short, your compost heap will get by just fine under normal conditions without additives. At the same time, adding certain substances and materials won’t do it any harm.

6. What you should know about composting.

A graphic shows what does and doesn’t belong in the compost.
There are plenty of things that you can throw onto your compost heap – but other things belong in the normal household waste.
A graphic explains how to best layer a compost heap. Humus is placed at the bottom and followed by alternating a layer consisting of green waste, shredded wood, small branches and straw and a layer of organic waste. The graphic shows two of each layer type.
If you layer your compost correctly, then you can look forward to nutritious humus for your plants at the end of the process.
A graphic shows what does and doesn’t belong in the compost.
There are plenty of things that you can throw onto your compost heap – but other things belong in the normal household waste.
A graphic explains how to best layer a compost heap. Humus is placed at the bottom and followed by alternating a layer consisting of green waste, shredded wood, small branches and straw and a layer of organic waste. The graphic shows two of each layer type.
If you layer your compost correctly, then you can look forward to nutritious humus for your plants at the end of the process.

6.1 What are the different types of compost?

Generally speaking, the following different types of compost exist: 1. Fresh compost is what’s produced after about three months. Some of the original materials can still be identified at this stage. What’s great about it is that it’s jam-packed with nutrients. It is particularly suitable for mulching according to environmental agencies. 2. Mature compost is more or less the end product. It is ideal for boosting the soil quality in any garden or on any balcony, especially just before you get planting in the spring. Even if you’ve waited a little too long for it to decompose, you can still use this compost. However, it will then have lost much of its effect as a fertiliser.

6.2 Does compost smell?

Generally speaking, you have to simply accept that compost develops its own unique smell. That’s why it’s also recommended that you don’t put your compost heap directly on the border with your neighbour’s property. However, if the stench becomes unbearable, it’s probably because the compost is too wet. This will give rise to unpleasant odours as the components putrefy. It gets wet if a lot of fresh lawn trimmings have been placed on the heap or if it has been set up incorrectly, for example. What’s more, a compost heap doesn’t suit everyone’s tastes in terms of aesthetics. That’s why we recommend selecting a more concealed location for it in your garden.

6.3 How does producing my own compost benefit me?

Plastic can be found in almost all conventional composts. This then enters the planted vegetable through the earth and ends up in our bodies. 

6.4 What is liquid fertiliser?

This is nourishing fertiliser made from your finished compost. All you have to do is put a shovel of compost in a bucket of water, give the mixture a good stir, wait until the heavy particles have settled and then distribute the liquid evenly over your plants in a watering can.

6.5 Are compost and humus the same?

While people generally tend to conflate humus (from ‘ground’ in Latin) and compost (from ‘composed’ in Latin), there are actually a few differences between the two. Compost soil is not fully broken down, which is the case for humus. While humus is a natural product – and develops without human intervention – compost is actively produced. When it comes to the composition of the most essential nutrients for plants such as calcium, iron and magnesium, there is barely any difference between compost that has been matured for several months and humus soil.

6.6 Is it true that compost heaps can go on fire?

Yes. It may be hard to believe, but many compost fires happen across the world each year. An overly thick layer of moist grass, leaves or hay in combination with too little ventilation is often the cause. The different chemical processes within the heap generate heat which can result in individual materials setting alight. That’s why you should make sure not to put too much grass or hay in your compost heap. It’s a good idea to dry it out a few days beforehand and mix it with smaller branches and shredded wood to be on the safe side. This boosts air circulation. But remember that a compost heap that’s too dry isn’t good either. Dampen your compost now and then during the hot summer months with a watering can. This also helps to decompose the different compost layers.

As you can see, a lot of thought goes into making good compost from decomposable waste. But don’t lose heart – mother nature will take on the majority of the work!