The Benefits of Earthworms and How to Recognise a Lobworm
Earthworms are among the most useful creatures in a garden. They help turn organic matter into living soil, improve its structure and create channels that allow air and water to reach plant roots. In a dry garden, encouraging worms is an important part of improving the soil’s ability to absorb and retain moisture.
How worms improve garden soil
Healthy soil contains mineral particles—sand, silt and clay—together with organic matter and a complex community of living organisms. Worms help connect all these elements. As they feed, move and burrow, they:
- pull leaves and other organic material down from the surface;
- break organic matter into smaller particles that fungi and bacteria can process;
- produce nutrient-rich casts;
- mix organic material with the mineral soil;
- create channels that improve aeration and drainage;
- help rain and irrigation water penetrate compacted ground; and
- contribute to the formation of stable humus.
Humus acts rather like a reservoir. It holds water and plant nutrients, then releases them gradually. This makes worm activity especially valuable where soil has become dry, compacted or depleted.
The lobworm: a natural soil engineer
The lobworm, Lumbricus terrestris, is also called the common earthworm or dew worm. It is Britain’s largest earthworm and is particularly useful because it creates deep, mainly vertical burrows. It comes to the surface, often at night, to collect dead leaves and other material, which it pulls into its burrow to eat.
These permanent channels help water travel deeper into the soil rather than running off the surface. They also provide routes for air and, later, for plant roots. Lobworms are therefore very different from the smaller composting worms that mainly live and feed close to the surface in compost heaps and wormeries.
How to recognise a lobworm
A mature lobworm is normally large, long and stout. When extended, bigger specimens can reach around 20–30 cm or more. Look for:
- a dark reddish-brown or purplish upper surface;
- a paler, sometimes yellow-orange underside;
- a pointed head end;
- a broad, flattened or paddle-shaped tail;
- a clearly visible raised band or “saddle” on a mature worm; and
- a deep vertical burrow, often with a small pile of casts and pieces of leaf around its entrance.
The saddle shows that the worm is mature, but it is not unique to lobworms, so size, colour, tail shape and behaviour should be considered together. Precise identification of earthworms can be difficult, but these features provide a useful guide for gardeners.
Encouraging worms in Harry’s garden
Worms need food, moisture and soil that is not continually disturbed. The most effective approach is to spread organic matter over the soil as a mulch. Garden compost, leaf mould, well-rotted manure and spent mushroom compost can all provide food for the soil community.
Apply the material over moist soil and water it if conditions are dry. A layer about 5–10 cm deep is useful when restoring badly depleted ground, while a lighter annual mulch will help maintain established borders. Avoid repeatedly digging the soil deeply, as this can destroy the lobworms’ permanent burrows.
Spent mushroom compost is especially useful for increasing organic matter and improving water retention, but it contains lime. It should not be used immediately around acid-loving plants such as rhododendrons, azaleas, camellias and blueberries. Use leaf mould, garden compost or an ericaceous material around those plants instead.
If suitable lobworms are introduced, place them onto moist, mulched soil during cool conditions, preferably in the evening. They cannot improve dry soil without food and moisture, so prepare the area first and keep it from drying out while the soil ecosystem becomes established.
Worms are a sign of recovery
Increasing worm numbers are a good indication that organic matter, moisture and biological activity are returning. The improvement will not happen overnight, but worms, fungi, bacteria and plant roots will gradually work together to create a darker, more crumbly and resilient soil.
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