Earthworms are vitally important in our gardens. They make our soil richer and improve its structure, thereby helping to absorb and retain moisture and reduce soil erosion and nutrient loss.

Every scientific study shows their value. Last month a paper published in Nature Communications by SJ Fonte of Colorado State University et al has assessed that earthworms contribute 140 million tons of grain globally, the equivalent to one slice of bread per loaf.

 There are broadly three types of earthworm in our gardens. Most of us would recognise “compost” or epigeic worms with their trademark red stripe along their backs. They live on the surface and feed on leaf litter and other decaying vegetation.

The second, anecic, group contains most of Scotland’s worm species. They have dark red or brown heads, the body turns pale towards the tail.  Like compost worms, they help to process rotting vegetation. They specialise in creating permanent vertical burrows for transporting fragments of vegetation throughout the soil.   

READ MORE: The ground rules for the winter veg patch

Thirdly, endogeic worms are responsible for processing soil. They make horizontal burrows through the ground and sometimes move backwards and forwards along their tiny tunnels.  These worms ingest microbes, bacteria, protozoa and fungi, which they digest and excrete as wormcast. It’s been estimated that wormcast could make soil 59% richer. 

It certainly has a higher NPK (nutrient) value and contains minerals, such as calcium, copper and zinc.  Other soil microbes continue the process of breaking down this fertile material and making it available to plants.

These endogeic worms not only excrete fertile wormcast, they break up and aerate the soil with their network of tiny tunnels. The sticky mucus which binds the wormcast into tiny crumbs also bonds with nearby soil particles. This creates the crumbly texture that absorbs moisture and retains nutrients, so is perfect for our plants.

The more we add organic material to our ground, the better it becomes for worms, so their population increases, thereby improving the quality of the soil.

So the last thing we want to do is apply synthetic chemicals, like path weedkiller or lawn treatments as this will damage the soil’s essential microbiome.  Digging and especially using a mechanical cultivator damages the structure of the ground and kills earthworms so should also be avoided if you want a healthier garden.

Plant of the week

Kalanchoe Blossfeldiana is a readily available houseplant that is easy to grow. A range of colours is available but these don’t usually have specific names. Kalanchoes need a bright spot and can cope with sun; now that the light is declining move to a south facing windowsill.

To get kalanchoes to flower again you need to give them at least two months of long nights, eight to nine hours of darkness. An unused room is easiest but you can put them in a cupboard in the evening as long as you remember to get them out in the morning.

Follow Dave on X @boddave