Sustainable and practical composting on the balcony

Throwing things away is so last year; kitchen waste is an ideal source of fertilizer. Start composting on the balcony and you'll find an ecologically sound use for a lot of organic waste.

Make your own fertilizer

Plant lovers are familiar with the big bins or open wooden crates with kitchen and garden waste decomposing outside that turns into valuable humus. Full of nutrients, when available in sufficient quantities it does away with the need to purchase fertilizer. The good thing is that you can also compost on the balcony. All you need is a little space and a few utensils.

For composting on the balcony you'll need:

• a container (bin) with a lid and at least a 75-litre capacity
• a trivet for catching any liquid
• two timber beams
• four bricks
• branches, twigs and leaves
• rock flour
• some ready compost

Composting on the balcony – how to do it

First, you'll need a container in which you transform kitchen waste or other organic waste such as cut plants into rich peat. The easiest way is to use a plastic bin with a capacity of more than 75 litres. This is enough to recycle the waste from a small household. A plastic composter will last around five years. You can also use another material, as long as it's not corrosive metal because rust introduces toxins into the rotting matter.

Holes in the floor and at the bottom of the container are important so that oxygen can circulate inside. This also avoids the spread of unpleasant odours. If it doesn't have any holes, you'll have to drill some. The distance between the holes should be about five centimetres. Depending on the size of the bin, you can make several rows of holes around the edge, one above the other. There is no rule of thumb, however.

The right foundation

Let's talk about the base. You can build this from the trivet, stones and beams. The trivet must be larger than the barrel and a little lower than the bricks. Put it in the desired spot and place the stones around it to the right and left. Two at the rear, two in front. Make sure there's enough space on one side so that you can pull out the trivet if necessary. Now place the two beams on the bricks so that they are stable and you can stand the barrel on them. Why all this effort? For several reasons. Firstly, the distance from the ground ensures air ventilation. Secondly, liquid will continue dripping out of the barrel. You collect this in the trivet. Once a certain amount has collected, pull the trivet out from under the structure, empty it and push back into place.

As you'll have noticed, good ventilation is necessary for composting on the balcony. Which is why you now fill the bin loosely with different thick, coarse-cut branches up to the top of the holes. This creates a thin layer of branches and leaves. When you finish setting up the composter, place the lid on top. To prevent the wind lifting it off, use another brick to weigh down the lid. Your balcony composter is now finished and ready for your waste.

It all in the content

The question is: what goes in? Ideally a mixture of damp, dry, fine, and coarse components to create a loose mass. We recommend adding rock flour and about 3% ready compost as a starter. This is because it already contains the micro-organisms and worms that carry out the decomposition. Important: the ingredients must be as small as possible. So don't use whole potatoes or onions. Finely chopped pieces are good because they will decompose more rapidly. You'll need to cut all the ingredients with a knife before composting or put them through a shredder.

Examples of suitable items:

• Apples and apple peel
• Bamboo
• Banana peel
• Potting soil
• Cauliflower
• Flower bouquets
• Bread
• Eggshells
• Hedge trimmings
• Wood shavings
• Used coffee grounds
• Potatoes and potato skins
• Foliage, leaves and needles
• Muesli
• Nut shells
• Mushrooms
• Grass cuttings
• Chocolate
• Rock flour
• Tea bags

Examples of unsuitable items:

• Flower fertilizer
• Flower pots made of clay and plastic
• Frying oil
• Cardboard
• Candle ends
• Leather
• Mussel shells
• Vacuum cleaner bags
• Animal droppings
• Cotton
• Nappies
• Newspapers
• Cigarettes

It's all in the mix

If you want to compost on the balcony, in addition to shredding the appropriate ingredients, you also need the right mix. A cocktail of soft, moist high-protein and carbohydrate-rich, dry and hard substances is ideal. A rule of thumb for optimal composition is a mix materials with 60% to 80% humidity and nutrient-rich materials that are 20% to 40% dry and low in nutrients. The first category includes food leftovers and garden waste such as grass clippings; the second includes waste wood materials (twigs, branches, hedge trimmings) leaves and nut shells.

The right balance between wet and dry is also very important. If the humidity is too high, the material will stick together, the oxygen will stop circulating and the compost will decompose. However, if it's too dry, the decomposition process will stop. Ideally, the material should feel like a squeezed sponge.

Always keep it nice and loose

Turn the mass over regularly to maintain a loose consistency. This supports the oxygen supply. And why is that so important? Because the micro-organisms and worms need it to perform their vital work on the compost. They process and break down the kitchen and garden waste into carbon dioxide, water – and the desired nutrient-rich humus.

Therefore they need to be cultivated and cared for, otherwise they will leave. Especially in winter. A large compost pile in the garden containing at least three cubic metres will generate temperatures of 50 to 60°C. That kills germs that carry diseases on the one hand and on the other, keeps the beneficial organisms nice and warm. When composting on the balcony this doesn't happen because the amount is too small. Therefore in freezing temperatures, you should wrap the barrel to protect it against frost. We recommend using bubble wrap.