Q: I dug some compost, that was full of worms, into my garden beds only to discover later that they had all vanished. Where have they gone?

A: Of the more than 7200 species of earthworm that live on our planet the ones that inhabit our compost bins are predominantly Red Wrigglers, or Redworms, as they are called in the US. They thrive on the mass of matter that decomposes within our refuse and can withstand much warmer temperatures than their ground-loving counterparts.

So where did they come from initially? From the soil, believe it or not. Many times I have started a compost heap and turned it a few months later only to discover the pile is a wriggling, writhing hive of activity. Red earthworms have moved into the pile and are now consuming copious amounts of kitchen and garden waste. These weren't introduced into the heap but came of their own volition.

So where do they go when they get dug back into the soil? The first thing to understand with earthworms is their voracious appetite. If you remove the food source then they just pack up and go looking for another source to quench their hunger.

Many people think that if you dig Red Wrigglers or Redworms into the soil they will die. This is not necessarily the case, though due to many reasons (ie. acidity/alkalinity of the soil, bad drainage, ultraviolet light - to name a few) they may die before finding the next banquet. What usually happens is that they leave because the soil lacks in digestible organic matter - the compost has possibly been devoured already - and head for greener pastures.

How can you entice earthworms into your garden beds?

Organic matter. And heaps of it. Mulches, composts and leaf litter are great enticers for earthworms. While the soil is impoverished and obviously needing the assistance that worms can provide, the top of the beds need to be covered with organic matter that will encourage them to return.

Keeping them active in the garden is just as easy. As the organic matter is broken down and turned into worm castings it needs to be replenished so that your worms don't go looking elsewhere to satisfy their appetite.

How do I know if my earthworms are satisfied?

You will know if your earthworms are satisfied when you can dig a sod of soil and at least 6-10 worms are present. This shows that the life-cycle is working well and that they obviously have enough to eat and the conditions are good. More than this and you may be overfeeding your garden beds and less will demonstrate that your garden is lacking in organic matter.

How can I get them started in my compost?

You could start your own worm farm and breed them from there. Another option is to buy RedWorms (aff.) and then add them to your compost, or you could just wait until they turn up by themselves.