Making a balcony composter can be easy. Marco Pagliarulo offers the following guidelines to make one like that shown in “A Downtown, South-facing Balcony, 5th floor”. Marco developed this composter with some ideas he found on the web, adding his own modifications.
- A large planter about 45 cm diameter, with a tray to catch excess water
- A pail about 27 cm diameter, at least 35 cm tall
- Potting soil
- A drill
- A saw with a narrow blade
- Cut out the bottom of the pail using the drill and saw. Drill several holes (lots!) in the pail and lid.
- Cut a little trap door in the bottom of the planter (about 12 cm by 12 cm). This is for removing the finished or near-finished compost from the composter. You might need to use something to keep the trap door shut when not in use.
- Put 5 - 10 cm of soil in the bottom of the planter. Drop the pail into the centre of the planter. Fill the rest of the planter (around the pail) with soil up to near the top of the planter.
- For aesthetics, plant some small plants in the ring of soil that surrounds the pail. Also, keep the lid on the pail and perhaps place a smaller planter on top of it.
- To keep your balcony composter odour-free, stick to these general rules:
—Do not throw any animal-derived products (meat, egg, dairy, fish...) or oily foods into your composter. Basically, keep it vegan and oil-free.
—Cut food scraps into small pieces (generally no larger than the size of a quarter coin) to facilitate breakdown.
—Every time you throw in food scraps, throw in the same volume of dried leaves, and stir everything deeply with a bamboo stick. The drilled holes help with passive aeration, but the stirring is important for aerating the bottom parts. Aerating keeps the composter breaking food down "aerobically", which doesn't smell.
- If your composter smells, it means that it might be too wet, or you're throwing in foods that shouldn't go in, or you're not aerating enough.
- Fruit flies: After you add food scraps and dried leaves, and after aerating, sprinkle some sand or crumbled dried leaves on top of the compost before closing the lid.
Most of the excess liquid from the composter is absorbed by the surrounding soil in the planter. As the composter gets full, the pail can be lifted a bit higher out of the planter to allow for passive aeration through the drilled holes.
When your composter gets too full, start removing the finished or near-finished compost from the trap door. If the compost is not finished yet, you can leave it in a separate pail for a few months or give it to someone who can pile it in the corner of their garden.
You'll find that the volume of compost coming out of your composter is only a fraction of the volume of food you put in.