Earthworms are the work force behind a healthy garden soil and this makes them invaluable to all productive food gardens. Worms feed on organic material that they find on the soil’s surface and its upper layers, they draw it down deeper into the soil and this improves its structure. The digested casts that worms produce contain around 50% more organic material than the soil surrounding them, they are also higher in key nutrients such as nitrogen, phosphorus and potassium. These casts are also full of digestive enzymes that make many nutrients in the soil more available to plants. Researchers have estimated that a single worm can produce about 5 kg of worm casts in a year. As they journey through the soil, worms open it up with their tunnels and these allow air and moisture to pass easily through it – all good for soil structure and plants. This supports healthy plant growth by helping plant roots to penetrate soil and find oxygen as well as moisture. A soil full of worms is being constantly tilled, worked, improved and revitalised and this saves us gardeners a great deal of time and effort.
The large bluish purple worms that often appear on the ground’s surface after it has rained or at night are deep soil worms. Often called ‘night crawlers’ they like cool conditions and in summer when its dry they can live several feet below the soil’s surface. These are the worms that till the soil, opening it up and drawing organic material through it.
In the upper layers of compost heaps and piles of organic mulch around the garden you should find small, skinny red worms – ‘red wrigglers’. These are surface dwelling worms that like the warmer temperatures found in decomposing material. ‘Red wrigglers’ rapidly consume organic material and break it down into valuable casts that enrich our home-made compost a s well as soils where mulch has been layered around plants.. These are the type of worms that are used in wormeries.
Layer organic material on your garden and keep it moist. Add new material every few weeks. Avoid using chemical fertillisers. If you feed worms they’ll feed your soil for you. Only dig your garden when you really have to and use a fork rather than a spade - you’ll injure less of these important recyclers.