Build a Worm Tower

Host: Leonnie Shanahan. More info: www.ecofilms.com.au

Mrs. Homegrown here:

One of our commenters on the compost debate, Nick H., offered up a link to a great video about worm towers, so we thought we’d share. A worm tower is a wide (at least 50cm dia.) pipe sunk halfway into the ground, with access holes on the lower half to allow the worms to come and go. Food and bedding is dropped in the top, which is kept capped.

We happen to have worm & compost expert Nancy Klehm staying with us this weekend, and she explained to us that this particular technology makes a lot of sense for hot, dry climates (note the video comes from Australia), because it’s sunken and it allows the worms to distribute themselves in the cool soil during the day. Conversely, I can imagine this wouldn’t be such a great thing in rainy climates as it could easily flood.

Nancy told us the worm holes clog up, so you do have to remove the pipe for cleaning fairly regularly, and perhaps take that opportunity to reposition it. I imagine that’s when the casting harvest would occur, and harvest promises to be a pretty messy process. 

The video speaks of using PVC pipe for the tower. PVC is cheap and easy to work with, but it’s pretty well established that it leaches toxins as it degrades, so you might want to seek out pipe in other materials. As an aside, we used to use PVC pipe in our self-irrigating pots, still still have PVC in some of them, but are phasing it out in favor of metal or bamboo pipe. Yet we still have PVC lines as part of our irrigation system. This is something you have to weigh and decide for yourself. 

Once Erik dragged home a section of ceramic sewer pipe he found in the street. It lingered in our yard for years, and was finally returned to the street. Now we’re singing the pack rat’s lament (See! See what happens when you throw things away!), because it would have been perfect for this.

On first glance I’d characterize this system as a novel idea, one which is worm-friendly, and best suited to hot, dry climates. It looks convenient to set up and use, but probably not the best system to use if you’re primarily interested in the castings.

If we can find another length of sewer pipe we’ll try it out and report back.

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14 Comments

  1. Would love to do vermiculture of some sort, but since composting worms are non-native and generally classed as an invasive species here in the great lakes north woods. Even in a closed system it is too much of a hassle to safeguard any composting or castings to make sure I’d not be introducing worms into the environment when I’d use the material in my garden beds.

    http://www.greatlakeswormwatch.org/default.htm <– more info if you are curious.

  2. Would this work in a rainy climate if the worm farm were on a high spot that drains well? If the worms carry the castings out of the pipe, where is the compost located for the gardener to use? I love the way she had her pipe decorated!

  3. Geographer: That’s fascinating!

    Parsimony: We haven’t done this ourselves, so I don’t really know much. I’d say it was worth a try on a high spot if you’ve got a pipe and worms to spare. My guess is towers are not so much about castings harvest as soil enrichment–but again, I don’t know.

  4. I’ve liked this idea except that I feel uneasy introducing a non native species of earthworm into the soil. Its one thing to keep them in a container but its very much another to let them loose in the garden

    I have plenty of earthworms in my garden (evidenced by their surface mating seen at night) so I also question whether this is even necessary

    Signed,
    Negative Nancy

  5. Negative Nancy:

    Well, be that way.

    ;)

    Dunno. Suppose it depends on where you’re from?

    Some things to consider: I hear compost worms don’t survive freezing winters, unlike nightcrawlers, so maybe they are less of a concern?

    For greater surety, I suppose one could raise worms in bins indoors and then freeze the castings to kill eggs.

    And of course, as you say, you probably don’t need them. That’s probably the easiest solution if you’re worried about it.

    Here in LA there is no worm prohibition so this whole issue is all kind of new and abstract to me. I think there’s a big difference between interfering with the soil in pristine place like the North Woods and the soil in my LA backyard.

  6. That’s a cool idea…it seems like it would be especially good in the center of your garden bed, so that the worms carry the castings around for you. The less work the better for me!

    I had a traditional manufactured worm bin here in LA for a while, but ended up selling it. I didn’t have a good shady spot to keep it in, and the chickens appreciated the scraps much more – then ate the few worms that had survived the heat too.

  7. Not wanting to commit to “livestock” ive taken an interest in “bokashi” as a way of getting rid of food scraps, Had any experience with it? that and the old way we used to do it in the seventies…just dig a hole in the garden and bury it directly, covering with soil as you go.

  8. @Brendie: We’re not bokashi experts, have never done it, but from what we know it seems like it adds an extra step and extra expense to what should be a very fundamental process. Worms are at least a self-contained disposal system, but as we understand it, bokashi waste still needs to be returned to the soil after pickling, so why not compost it from the start?

  9. my thinking is….bokashi is rodent safe, some people have written about a DIY way where the fermented bokashi is then used as a starter for the next bucket a bit like yoghurt culture and using shredded newspaper instead of the grain. my garden trimmings are composted and i dont have much food scraps. just thought you might have had some dealings or heard of any feedback :)

  10. I will be moving from Seattle to LA this summer. I have had a lot of success with wormbin composting here in Seattle and would like to continue composting once we move. The composters I use are made of plastic and clip 4 sides together with a lid and open bottom, about 2 1/2 feet wide and 3 feet tall. I’m wondering if I could simply bury the bottom half of this composter and get the same result as the PVC Tube? I’d like to bring my worms with me when I move (does that sound crazy??) Would it be wrong to bring Seattle compost to Los Angeles?

  11. Actually this method of vermicomposting works fine in a moderate climate like Switzerland. In winter, the worms move into the soil, and as this is open at the bottom it doesn’t waterlog.
    As a similar idea we use wooden wine boxes, remove the bottom and use as lid, between bushes. We don’t bother digging them in, just lift up to harvest compost. Discreet and improves the fertility of our garden.

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