4 Vermicomposting Tips

Ecological landscape designer Darren Butler has been teaching a series of classes at the Root Simple compound this month (I think there may be a few open slots in his Intermediate Organic Gardening class if you’re interested. Click here for details). Darren dropped a few vermicomposting tips during the beginning class that we thought we’d share:

1) Worms don’t like empty space in their bin. They dislike voids. They appreciate it very much if you bury their entire working area under a very thick layer of light dry carbon material, like shredded newspaper or chopped straw. Yes, it’s standard practice to put a layer of cover material over the scraps–but the difference here is that Darren recommends that the cover layer should fill all the empty space in the bin, from the worm level to the lid.

To be clear, you never want the bin’s working material (worms, scraps, etc.) to get super deep. That’s just asking for problems, because the deeper that material, the more likely the bottom is going to turn nasty and anaerobic. What we’re talking about here is filling the empty air space with dry matter–sort of like an insulation layer.

2) Harvesting worm castings (separating the worms from the castings) is always a bit of a challenge. Well, not challenging as in hard, but challenging as in requiring patience. Our method has been to mound the castings into a pyramid outside on a sunny day. The worms instinctively work their way down to the base of the pyramid to avoid the light. Once they do, we take off the top and sides of the pyramid and transfer that to a bucket. That material will be mostly worm free. Then we reform the pyramid and do it all over again.

This method is fine, but Darren’s method is a little faster. It works on the same principle–the photosensitivity of worms–but instead of making pyramids he lays out softball sized mounds of castings. The worms will cluster at the bottom of the balls, allowing you to harvest off the tops and sides. This works faster than our pyramid method because the worms don’t have as far to move. You can harvest faster, and get it done all at once instead of forming and reforming the pyramid.

Of course when you’re doing either method you should remember the worms are very vulnerable when they’re out of their bin like this, vulnerable to heat and sun–you don’t want to forget about them!–and also to predators like chickens, birds and even dogs.

3) Some of you have worm bins with spigots for collecting “worm tea” aka leachate. Did you know it goes bad within 24 hours of production? If you use it, use it right away. Never use undiluted leachate on plants–it can harm them. To use it on plants, dilute it with 4 parts water, put it in a spray bottle, and spray on foliage. They’ll uptake the nutrients through their leaves. Alternatively, you can use it as a soil drench (for watering) when diluted with 16 parts water. In its straight form it can be used as an insecticide.

4) Darren’s favorite way of using worm castings is new to us and quite interesting. Castings are fertilizer, but more than that. They can help bring life to your soil. He takes golf ball sized plugs of fresh castings and buries them here and there in his garden beds (or pots). Used this way, they are little beneficial microbe arks that will help invigorate the life of your soil. A little bit goes a long way. You are, in effect, inoculating your soil with microbial life.

New to worm composting, or just vermi-curious? The classic book on the subject is Worms Eat My Garbage: How to Set Up and Maintain a Worm Composting System by Mary Appelhof.

Leave a comment


  1. Interesting! I tried vermicomposting a few years ago using a two bin system. It worked for awhile and I enjoyed it, but it got to a point where the worms just wanted out. I wonder if it was because I didn’t fill my bin to the lid, as in tip #1 (hadn’t heard of this before).

    I ended up moving all the red wigglers to my outdoors compost pile. In winter I heavily mulch and protect the pile… There are still redworms there doing their job, hopefully descendents of my initial red wiggler purchase!

  2. I’m on my way down to fill the bin’s empty space right now! Re #4, I use castings in my soil block mix for the same effect at transplant time.

  3. In addition to raising worms for the castings, you might consider “planting” some worms directly in your garden. I came across an article in FarmShow (www.farmshow.com) magazine a couple of years ago about vermipods (www.vermipods.com) by Bill Kreitzer. I ordered some from him for my garden and they did help increase the earthworm population in my soil. I plan on ordering some for the spring for an additional garden patch I am working.

  4. Can vermicomposting of kitchen scraps be done in wooded rural areas? I have done it for years in suburban Chicago and plan to move to rural WI and would like to continue there. I have heard that composting worms may ” escape” and then multiply in the forested areas and breakdown the leaf litter on the forest floor, altering the ecosystem. Is this true? If,so any alternatives? Thank you.

  5. @Anon: This is outside our area of expertise, but we’ve been told by a worm expert from your area that it’s not such a worry, because the few escapees you might have will not be able to build sufficient populations to create a threat. Of course the alternatives would be to keep the worms indoors, in your kitchen, basement, shed or garage. Our bin has been in our kitchen for years with no problems–we’re just moving it outdoors this week for the first time.

  6. A very timely article. I just did my own blog post about verimicomposting. I plan on building a worm bin soon and will get it running for the winter.

    This is the first time I have heard about filling the bin with bedding material. I would think this would make it difficult to get the food down to the worms. But I’ll take a look when I get mine built.

    I’ll likely be doing the rubbermaid tote bin to get started. But some of those flow through designs are pretty cool

  7. Thank you. I have been thinking about my worm box. I had heard that they needed “browns” such as coconut coir, but then I heard I could use dried leaves also. I can now stack the knowledge gleaned from here for the betterment of the worm box.

  8. @Mil: Right, they do need browns to keep the bin airy–if it was just veg scraps and their poop it would get real swampy. Dried leaves are good, as coir, as is newspaper and shredded plain cardboard. A worm bin should look like a compost heap, basically.

  9. I have been shredding mail and other papers printed on standard copy paper and adding it to both my compost and worm bins. I thought I had read in one of your books that that was okay. Is it not safe to use copy paper for these purposes?

    • Many people use copy paper in their bins. The standard wisdom is just not to use shiny, colored paper, e.g. advertising flyers and newspaper inserts. Some people are more fussy and distrust the printer inks on office-type paper, but worms are nothing if not adaptable, and basically if something seems to be working in the worm bin…then it works.

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