In-ground Worm Bins

Looks like today is going to be another busy ‘Reader Questions’ day. I’ve been getting some really good ones lately and have been enjoying answering them here! This first ‘question’ (which isn’t really a question) comes from Felicia. She has an interesting idea for keeping her bin warm/cool and I thought others might benefit from her creativity.

I would like to start out with European Nightcrawlers in
hopes of raising worms for fishing as well a composting. Today, I
started a plastic bin (10 gallon) with moist peat moss and a small
portion of, coffee grounds, and onion and potato peelings. Since I
live on the outer banks of North Carolina, and it turned cool again
today, I sunk the bin in the sand under my home about 3/4 of the way
up in hopes that it will keep the bin warm in the cool weather and
cool in the warm weather. I added to that about 8 worms from my
garden just to try it out. I have since read your recommendations
against yard worms.

Hi Felicia,
I’ll often recommend in-ground worm bins as a way to help keep worms warmer during colder months, and you are absolutely right – the opposite effect can expected in hot weather. The earth is an excellent insulator and isn’t affected by rapid air temperature changes. Keep the bin under your home is also a great idea since it will provide even more shelter during hot/cold periods.

I especially like your idea since you can pull out the entire bin when you want to harvest castings (although, it will certainly be very heavy) – whereas a truly in-ground system would be quite difficult to work with, assuming you ever wanted to remove worms and/or worm castings.

If your area gets especially cold during winter months you may need to take some extra steps to protect your worms from the cold. You may need a larger system to help generate (and hold) more microbial heat, you may need to sink it further down into the ground, and you might also want to add a thick layer of insulation over top (straw, leaves etc work well).

For your particular bin (the one you described above) I would recommend adding more food waste, and also mixing in some shredded cardboard or newsprint. Peat moss is a good bedding material, but you’ll get better air flow if you also add some other bulkier materials. When first starting a bin you can definitely get away with adding more food scraps – assuming you then leave the bin for awhile before adding your worms. This allows time for lots of microorganisms to colonize the materials and for moisture levels to balance out.

You are right about the garden/yard worms – I definitely don’t recommend adding them to a vermicompost bin. If you system is in direct contact with the soil (i.e. isn’t sealed) plenty of regular earthworms will venture into the lower regions to feed on organic matter, but you won’t find an abundance of them up where the composting worms are. Most regular soil dwelling worms require cooler, less crowded conditions in order to thrive. The worms you added may survive for quite some time, but the chances of them reproducing (assuming they are even the same variety) is slim to none.



[tags]worm bin, composter, worm composter, outdoor worm bin, vermicomposting, worm composting, composting worms, earthworms, earth worms, european nightcrawlers, composting[/tags]

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    • Scott Adams
    • April 1, 2008


    Just a note. The earth is not an insulator it is a capacitor. If it was an insulator the the suns rays would not warm it up at all. As a capacitor it helps mellow out the fluctuations of the air temperature if you are down far enough.

    I love reading your information on all of your blogs, and am currently thinking about starting a red worm bin this summer out site as a starter.

    • Bentley
    • April 1, 2008

    Thanks for the technical clarification, Scott. As John Carson would say, “I did not know that”.

    As for starting your own worm bin this summer, I say GO FOR IT! (but I’ve been known to be a wee bit biased – haha)

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