Why Do Earthworms Gather at the Top of Compost Bins or Worm Farms and Try to Escape?

Compost worms in worm farms and earthworms in compost bins can often be seen gathering in large numbers inside the lid, often trying to escape. This usually happens when it’s about to rain. Before it begins to rain, the air pressure (barometric pressure) in the atmosphere drops, and the worms can sense this, so they climb to the top to avoid drowning. This is a natural survival instinct for when the rain floods their burrows and tunnels in the ground.

If rain is coming, then this is a normal response from worms, and is perfectly natural. If there’s no rain in sight, then this may be an indicator something unpleasant or harmful has been put into the worm farm or compost and may need to be removed. For more information about what materials can and cant be put into compost and worm farms, please see the articles – What Materials Can You Put Into Your Compost Bin and What Not to Compost and The Complete Guide to Worm Farming, Vermicomposting Made Easy.


  1. I know of a research paper written for the uni I went to in Swansea. It is all about worms and how they have a preference for previously burnt soil. Not sure if that was why the research was started, but that was the result. To me it didn’t make sense, as other papers have said fire decreases soil nutrients. Anyways, there’s that.


    1. Hi and thanks for your comment which got me thinking!

      If I go back to my chemistry background, when plant materials are burnt, many plant nutrients are lost, especially nitrogen (N) and organic carbon (C), as well as phosphorus (P) and sulfur (S) to a lesser degree. Wood ash is mainly comprised of calcium (Ca), potassium (K), magnesium (Mg), silicon (Si) and phosphorus (P), so these nutrients remain in greater concentrations. Wood ash leachate contained around 92% hydroxide and 8% carbonate, and when this is combined with the base-forming calcium and magnesium cations, these create basic (alkaline) compounds which increase soil pH. Calcium carbonate, which is garden lime, is usually formed, increasing alkalinity and altering the availability of nutrients. Some nutrients are converted to forms which are more water soluble and tend to leach away, being lost that way. A lot happens when plants burn!

      After a fire, there are less of some nutrients, while others become more concentrated, and here in Australia where we are prone to cyclical bushfires, we see that many plants and trees have adapted to fire, and their seeds germinate when exposed to heat or smoke, after which they spring up to take advantage of the nutrients released from plant materials by the fire.

      I’m not sure what would be left for worms unless the fires are mild, as they eat decomposing organic matter, which gets burnt off in fierce bushfires. I’m guessing in cooler climates, where soil profiles are deeper, the organic matter deeper down survives unscathed.


  2. I’ve been working towards owning a farm for years. But i only recently discovered permaculture. I fell in love with the idea of working with nature instead of against it. I’m been resigning my farm to function with diversity, no till gardening, annuals, self seeding plants, native plants. That’s what I remember of the top of my head.

    But I’m finding many of my searches turn up dry. They give me the principles of permaculture, but no real answers. For instance, I understand the fruit tree guild, but are there fruit trees, any trees, that shouldn’t be close to each other? Can carrots, onion, garlic, put under trees be protected from winter with natural leaf fall during autumn? … or must I cover them with hay and mulch? Can anything other then Timothy Hay be dried and used for winter fodder?

    I forgot to mention. I’m honestly considering just seeding EVERYTHING when I get on my property. I mean that literally. What if I just tossed the seeds everywhere? Put up a good perimeter fence to keep animals on the farm. Fence my animals OUT of the controlled garden, instead of inside pastures? How bad could it turn out? I can’t see how I could possibly be “working with nature” more then that.
    Any opinions on such a plan.

    These are questions that I’m not finding answers for. Anyone help?


  3. My raised bed is mostly in plastic bins. After a medical crisis and several years of neglect, it was overrun with demon weeds. Endless winding, thick, nameless weeds I’m still digging out. Have I ruined my soil putting it in covered bins?! I planned on using worm castings, Azomite, and compost, but after reading this, I’m wondering what else I need to do before putting the soil back into the raised bed?


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