Earthworm Compost Survey

Are there earthworms in every compost bin in Britain?

A bucket of compost!
A bucket of compost!

That’s what we wanted to find out and we asked you to help us! Many people have compost bins or heaps in their gardens as they are an excellent way of recycling garden and household green waste. The resulting compost is excellent for potting and a good fertiliser for use in the garden.

In many of these bins you will find earthworms. But, how do they get there? Some people buy earthworms to put in their bins, others get them from their neighbours, in some bins the earthworms just appear by themselves. We wanted to know where all these earthworms come from.

Aims of the survey

The Earthworm Society of Britain aims to promote and support scientific research so that earthworms and their environment can be better understood. You helped to contribute to this research. 

From your survey results survey we can begin to understand:

  • How widespread compost earthworms are
  • What affects where they do and don't live
  • Where the earthworms might come from
Compost survey report
Compost survey report

Survey history and results

In 2011 we first ran the Earthworm Compost Survey. We had a great response, over 225 people told us about their compost and 209 people found earthworms in their compost! The results of the survey were very interesting, we found out that most earthworms are not placed in the compost bins by enthusiastic gardeners but instead they just turned up in the bins. In the case of sealed compost bins where the earthworms had not been introduced deliberately earthworms were also found, which infers that the earthworms were arriving in the bins through garden waste.

What do you put in your compost bin?Another interesting result was the number of people who put citrus fruits in their compost bins; we found that 66% of respondents added them to their compost. Surprisingly this did not seem to affect the earthworms, because they were still recorded in the compost with citrus. This throws doubt on the commonly held belief that citrus fruits make conditions too acidic for earthworms. We would like to understand more about the affect of citrus fruits on earthworms, if you put citrus in your compost please do let us know how this affects the earthworm population in your bin. Finally, we found that the most popular things people put in their compost were: garden waste, kitchen waste, egg shells and tea bags.

The survey was re-launched in September 2014 and you can find a summary of the results in our Earthworm Compost Survey Report 2015. The survey will be re-launched in 2020 as part of the World Earthworm Day celebrations.

Did you know?

The earthworms that are found in compost are quite special and are different from earthworms that you may find when digging up your garden. They help break down the green waste that is put into compost bins and make it easier for bacteria to complete the composting process.

Thank you