Vermicomposting: what it is and how to do it – Lisboa Green Capital 2020
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Vermicomposting: what it is and how to do it

With no great demands on space, time or equipment, these worms take care of the party alone and help us recycle the garbage we produce in the kitchen.

Vermicomposting is a form of composting that relies on the work of worms in conjunction with other natural microorganisms. This biological process is an option to transform the organic waste that still produces a substrate rich in nutrients to fertilize the plants. Do you want to know how to make a homemade vermicompostor, ideal for small urban gardens, patios, terraces or balconies?

The vermicompostor can be built on the basis of a wooden box with a lid, about 60 x 30 cm in base and 25 cm high. Wood is the ideal material because it is insulating, keeping the container cooler in summer and warmer in winter. It is necessary to make some holes in the bottom of the box, for drainage, and in the side walls, for ventilation. It should be placed in an airy place, sheltered from light, cold and heat and kept with the lid closed.

What waste can be added?

Although worms’ diets may vary from species to species, they mainly eat fruit and vegetables, potatoes, beans, coffee grounds or eggshells. But not all kinds of waste can be given to the worms because they are harmful to their health – things like citrus fruits (lemon, lime, orange), meat, fish, seafood, salads seasoned with vinegar and oils, fried, ash, are a “no no” when it comes to feeding them.

Vermicomposting: How to start?

1.You should line the base of the tray with a “bed” of crumpled and moistened newsprint strips, thus filling the entire bottom of the container. You can use old newsprint sheets and avoid paper with coloured inks – heavy metals are harmful to worms and contaminate the compost;

2. Place four cups of soil (this introduces different microorganisms that help the worms digest);

3. Add the worms over the vermicompostor bed;

4. You can put a few more damp newspaper leaves and start to put the leftover food, cut into small pieces, to facilitate decomposition;

5. Leave the box of worms at rest, without adding more food for a week, so that the worms can get used to the new environment and start decomposing the food waste;

6. After the initial week, add food to the box three or four times a month. Start by moving the “bed” a little and spread the leftover food evenly and cover it again with the “bed”, carefully turning the material with a rake;

7. It is advisable not to place the waste in the same place every time;

8. When the compost is ready and you want to remove it, you should put coffee grounds or fresh organic waste in one corner of the container. The worms will be attracted to this place allowing the collection of the compost;

9. Keep no more than two centimetres of waste above the worms. If the vermicompostor starts to smell, you’re probably putting too much waste in. Interrupt the placement of waste for one or two days. Gently re-stir, aerating the bed using a tool with rounded tips or your hand;

10. Add moist newspaper strips, or dry leaves, when it is necessary to keep the food covered or the humidity levels; this also helps to avoid attract flies. Close the lid of the tray after each operation to add worms, food or bedding.