Abundance of earthworms - Ask Extension
Hello. Someone suggested I ask this here, I hope this is correct.
Every time it rains we have so many earthworms on our driveway and porch. I have n...
Knowledgebase
Abundance of earthworms #925943
Asked March 12, 2026, 7:00 PM EDT
Hello. Someone suggested I ask this here, I hope this is correct.
Every time it rains we have so many earthworms on our driveway and porch. I have never seen anything like it. Do you know why there would be this many?
Every little line in these pictures are worms. There isn’t any tree or yard debris on the driveway.
*I’m aware that worms come out when it rains and that worms are a sign of healthy soil. I have never seen anything like this before.
Marion County Oregon
Expert Response
Dear Betsy,
Thanks for contacting us about the abundance of worms on your driveway after a rain. It's difficult to say when there are 'too many', but I understand the nuisance on your driveway.
Actual earthworms are non-natives but ubiquitous. While worms generally indicate a healthy soil, they also consume vast amounts of organic matter and can disturb the soil peds. A 'health soil' has up to 5% organic matter. More than that is not good for the environment since the run off will contribute to algae blooms in water ways among other problems.
Another reason that there are too many worms might be poor drainage in the surrounding beds or lawn. Worms come out after rain or irrigation because they cannot breathe. (They also congregate under cardboard mulch layers for the same reason.)
Review your cultivation practices and consider a soil test. This may indicate the causes for so many worms. I hope this information is helpful. Please write again any time you have questions.
Thanks for contacting us about the abundance of worms on your driveway after a rain. It's difficult to say when there are 'too many', but I understand the nuisance on your driveway.
Actual earthworms are non-natives but ubiquitous. While worms generally indicate a healthy soil, they also consume vast amounts of organic matter and can disturb the soil peds. A 'health soil' has up to 5% organic matter. More than that is not good for the environment since the run off will contribute to algae blooms in water ways among other problems.
Another reason that there are too many worms might be poor drainage in the surrounding beds or lawn. Worms come out after rain or irrigation because they cannot breathe. (They also congregate under cardboard mulch layers for the same reason.)
Review your cultivation practices and consider a soil test. This may indicate the causes for so many worms. I hope this information is helpful. Please write again any time you have questions.
