The worm farm

Worms are an essential part of any garden ecosystem. They convert organic matter into directly absorbable plant nutrients while aerating the soil to improve drainage and root growth.

In an organic garden, vermicomposting can be used even more effectively. In our community garden setting in Rotterdam, worm towers have been set up with plans to scale composting capacity over time.

Not all earthworms are suited for a worm bin. Common earthworms prefer deep soil and will quickly attempt to escape. Red wigglers and tiger worms (Eisenia fetida) are the best candidates, naturally found in compost heaps and manure piles. Getting started with a handful from a composter is often the easiest route.

Worms thrive on pre-digested matter, meaning microorganisms begin breaking down organic waste first. Worms process a wide variety of scraps, producing rich worm tea (liquid fertilizer) and nutrient-dense vermicompost. Once diluted 1:10 with water, the leachate makes an exceptional organic liquid feed without the risk of burning roots.

1. Position the farm in a sheltered, shaded location
2. Use only uncooked organic scraps and kitchen trimmings
3. Horse manure is highly favoured by compost worms
4. Coffee grounds and tea leaves work exceptionally well
5. Citrus and onion scraps should be avoided or used very sparingly
6. Crushed eggshells add valuable calcium and regulate acidity
7. Chop coarse scraps finely before feeding
8. Keep a balanced balance between moist food scraps and dry carbon materials like shredded cardboard

A DIY worm farm can easily be built with stacked buckets or bins. The bottom tier collects liquid leachate and is fitted with a drainage tap, while perforated upper tiers allow worms to migrate and process organic materials. Keep the bin well aerated, ensure proper moisture levels, and allow the worm colony time to establish naturally.

Sources of failure:

1. The bin is too warm or exposed to direct sun
2. Leachate is not drained regularly and floods the bedding
3. The bedding is excessively acidic
4. The mixture is too wet or too dry
5. The compost layer has become compacted and airless

Addressing issues usually involves adjusting moisture and aeration with extra torn cardboard, or rebalancing acidity with crushed eggshells.