Saturday, March 3, 2012

Herding Worms for Fun and (Garden) Profit

One of my friends wanted to know about homemade worm bins and about caring for the worms. Since I have a homemade bin and have been caring for worms and using their products for several years, I thought this would make a good blog post.

I do not disrespect the worm bins available for purchase. As another friend commented, it’s easier and less messy to remove worm castings and worm tea from commercial bins. If you have the money, you can buy a good bin and enjoy all the benefits of it. That said, those of us who are living low by choice or necessity may not wish to, or be able to, purchase a good commercial worm bin. I preferred not to and so rigged up the homemade version and learned how to work with the worms. If you’re willing to get up close and personal with worms and their products, you too can keep worms in a free or cheap bin and enjoy the benefits.

Worms are a form of livestock - a small, pink, and wiggly form that’s easy to manage in a small space. As with any livestock, you must meet their needs in order to be a successful worm herder. Your worms need food, water, shelter, and each other, and they need to have their waste products removed before too much piles up. You can provide all of their needs in a small enclosed space located in a cool area like a basement, closet, or cabinet under a sink, and you can use things you’d otherwise throw out to provide their food and bedding. Their waste products, known as worm castings and worm tea, make excellent fertilizer for container plants, seedlings, and gardens. The worms themselves are good fishing bait or can be part of the food source for other animals such as spiders, amphibians, reptiles, or chickens.

As with any gardening topic, lots of people have developed lots of different worm bins and methods to manage their worms. I’ll tell you how I do it below; you can search for worm bins on the ‘Net to learn more. At the end, I’ll suggest an improved version of homemade bin that some of you might want to try.

Below is a photo of my worm bin. It’s the familiar brand of blue plastic tub with lid. Dimensions are approximately 20 inches long by 13 inches wide by 8 inches high. There isn’t anything special about this size, except that the height is within the 8 to 12 inches usually recommended for a worm bin. We’d purchased it for some other reason but it wasn’t being used at the time I wanted to start a worm bin. In practice, it’s too small to accept all the fruit and vegetable wastes that Mike and I produce; a bin twice this size would be needed if we fed all this waste to our worms (we compost what the worms can’t eat). The bin is in our basement because it stays within the 50-80ish F temperature range that worms can tolerate. You can put yours wherever you have the space as long as that space stays within the temperature range.

You’ll be herding red wigglers, a type of red or fishing worm that goes by the scientific name of Eisenia foetida. If you know someone who has a worm bin, ask her/him if you can have some worms to get your bin going. If you don’t know anyone to ask for some worms, buy one or two pounds of fishing worms (not nightcrawlers; that’s a different species) depending on the size of your bin from a local bait supplier.

Bedding for the worms is waste paper. Any sort of paper works, including newsprint, junk mail, and office paper, although you might prefer to avoid glossy ad inserts as some of the inks may have toxic ingredients. Colored newsprint uses soy-based ink which is supposed to be nontoxic. You’ll need to tear the paper into strips about 1 inch wide since your worms can’t do this themselves. If you’re shredding paper for security reasons, the shreds make excellent bedding and save you some work. If you can find a hand-crank newspaper shredder like the one Mike found among his dad’s tools (see photo below), use it to shred paper. Autumn leaves also work as bedding, if you don’t have sufficient waste paper.

Your worms’ food and water source is the fruit and vegetable waste that your household produces: all the parts that you don’t eat can be fed to worms. If it’s rotting or moldy, the worms won’t mind. Our worms do fine on tea leaves and coffee grounds; in fact, these constitute a large percentage of their diet. Our worms don’t get along well with excess citrus waste, like one or more citrus fruits’ worth of waste for two or more days in a row. I don’t know if it has to do with the citrus waste being too acidic or if there might be something that is toxic to worms in the waste. The occasional citrus peel may not be a problem, but I keep it out of our worm bin (it’s fine in our compost pile). The only veggie waste I might not feed to our worms are peanut shells, and only because it takes a long time for them to break down. You can put fruit pits in the bin, but they are too hard for the worms to eat, so you’d do better to compost them separately.

As for other food waste, the worms don’t mind eggshells, but they don’t break down rapidly. It might be best to crush the shells before you put them in the worm bin, or a compost pile for that matter. All the worm bin information I’ve read says not to put meat, fat, or dairy waste in the worm bin. In my experience, the occasional bit of salad waste with an oily dressing, or the occasional bit of a cheese or meat sandwich that didn’t get eaten, doesn’t seem to bother our worms, but they might not appreciate a steady diet of these. For all I know, the live worms might be eating the dead ones. Something must be, since the bin doesn’t fill up with dead worms.

Our worms seem to do fine on the water which comes in with the various sorts of wastes that they get fed. If the bedding ever seems too dry, you can sprinkle some water on it - but be careful if you do. Worms like some moisture but not so much that they can’t breathe.

Look back at the photo of our bin, and you’ll notice that the bin appears to be sitting inside a larger tray. It’s actually propped above the tray by two bricks. I drilled holes into the bottom of the bin so that excess liquid, known as worm tea, can drain out of the bin and into the tray. We were fortunate that Mike had scavenged the large tray before we started the bin. You’ll have to drill holes in the bottom of whatever you use for a bin, too. If you don’t have a large enough tray-like object that the whole bin can sit above it, find whatever container you plan to use to collect the tea, and drill holes in the bin in such a way that the pattern of holes are all above the container you are using to collect the tea. The articles I have suggest drilling at least twenty 1/4 inch holes in the bottom of the bin to allow for sufficient drainage.

Bricks can easily hold the bin above whatever container you use for collecting worm tea; if you don’t have bricks, stacked pieces or blocks of wood or any other dense, thick material should work. Whenever you see liquid in the container, pour it off and use it (I dilute it with water to the color of weak tea before using it). You can water container plants or garden plants with the diluted worm tea to give them an extra boost of nutrition.

To get your worm bin started, fill it with shreds and/or strips of paper or a mix of such paper and leaves to a couple of inches below the top of the bin. Mix in a few cups of garden soil; it contains grit and minerals that the worms need for good digestion and health. Put in the worms and some food waste so they can start eating. Then cover the food waste with more paper (the worms feed under the surface of the soil, so anytime you add food, always cover it with paper). Put whatever lid you’re using on the bin to ensure none of the more adventurous worms crawl out of the bin. Your worms will start eating and pooping. Every few days, open the lid and use an appropriate tool to pull aside some of the paper over the food waste (I use a short-handled garden cultivator). If your worms have eaten much or all of the waste, add some more, cover it, and put the lid on. The articles I have suggests that a pound of worms needs about a cubic foot of bin space to live in and can process about a half pound of food waste per day, presumably at room temperature. The worms eat more slowly at the cooler end of their tolerance range, more rapidly at the warmer end. As you get familiar with your worm friends, you’ll get a sense of how much they can eat and how often to feed them.

Worm poop is for some reason called worm castings. You’ll want to collect it on occasion, both because the castings are a powerful and valuable organic fertilizer and because too high a concentration of castings hurts your worm friends. The easiest way I’ve found to do this is to add food to only one side of the worm bin for about three months, then switch to the other side for three months and harvest all the bedding, now converted to castings, out of the first side at the end of the second three month period. Allow me to illustrate below.

Here’s what the inside of our bin looks like. You’ll notice the paper on the right side looks whiter than that on the left. That’s because I’ve been adding food on the right side, leaving the remaining food and bedding on the left side to be digested for the past couple of months. When the time comes, I’ll harvest all the material, now worm castings, out of the left side.

I’ve just added some food wastes to the right side of the bin.

I’ve covered the food wastes I added to the right side.

Then I put the lid back on. I’ll add more food wastes and bedding to the right side for a few more weeks. At the end of March, I’ll remove all the castings from the left side and put them into another container; most of the worms will have relocated to the right side, where I’ve been adding food and bedding. After I remove the castings from the left side, I’ll add fresh bedding, a cup or two of soil, and some food wastes to the left side, covering the food wastes as usual. Now I’ll add more food wastes to the left side of the bin for another three months. At the end of the three months, I’ll harvest the castings from the right side, add bedding, soil, and food wastes, and continue as above.

Once you have some worm castings, you can add them to the potting soil or seed starter mix that you buy to add fertility and organic matter, or use them as part of a homemade potting soil or seed starter mix. If you’re adding castings to a commercial product, use about 1 part by volume of worm castings to 8 to 10 parts of the commercial product. (You can use a flowerpot, yogurt container, old plastic cup, or suchlike as the “part” in these formulas.) I make my own mixes out of garden soil, compost, and worm castings. I use about 1 part of worm castings, 6 parts of compost, and 4 parts of garden soil to make a mix that I use for container plants and seed starting. I like to have more compost than garden soil in the mix in order to lighten the mix a bit; if I’m running low on compost, I’ll drop to about 4 parts of compost. If you have clayey soil, you’ll probably need less soil and more compost than I’m using. Mix the soil, compost, and castings together in a large bucket; I use a garden cultivator to mix them. The mix seems to be fertile enough to keep my container plants in good shape. It grows really healthy seedlings for the veggie garden!

If you want worms for fishing or food for another critter, take off the lid and poke through the side of the bin that you are putting food in. You should see worms. See if you can remove some worms and associated bedding using a trowel or a small container. So far I haven’t had much occasion to remove worms, so you’ll have to look up more information and experiment if you want to harvest worms from your bin.

Most of the time, you won’t have any trouble with your worm farm, as long as you keep the worms fed, not too wet, and remove castings at the right time. Sometimes you may find other insects or arthropods in the bin, but they aren’t cause for concern, as they are part of the bin ecosystem. The only trouble I’ve had is when the bedding gets so moist that the worms can’t stand it anymore. They go on a worm stampede, crawling en masse out of the top of the bin and onto the basement floor in search of more congenial quarters. They die before they find a better home. Trust me, you don’t want a mass of red worms dying on your basement floor. The surest way I’ve found to avoid this is to remove the castings every three months or whenever I notice an accumulation of worm tea in the tray, whichever comes first.

If you don’t want to keep the worms in a plastic bin, you could make a bin out of wood. An article in the May 1995 issue of Missouri Conservationist by Doug Newman describes his worm bin, a 1 x 2 x 3 foot box built from exterior grade plywood and finished with polyurethane varnish to help keep the wood from rotting. If you don’t want anything quite that fancy, use what wood you have, but I’d avoid treated wood (it might be toxic to the worms) and the stuff that’s made from pressed wood fibers (too weak and too susceptible to rotting). If you don’t varnish the wood, you’ll have to build a new bin every few years as the wood rots from the moist bedding. Even with varnish, the wood may rot eventually and the bin need rebuilding.

A friend of mine made a worm bin out of a plastic bin she’d been issued by her trash hauler for recyclables. After St. Louis County issued larger rolling bins for recyclables, the older bin was no longer being used, so it became her worm bin. I have a similar bin, shown below.

This bin is deeper than 1 foot, which allows for the possibility of adding a hose bib to the bottom of the bin and constructing a false bottom to make for easier worm tea collection and removal. Plug the drainage holes in the bottom of the bin, add a hose bib so you can easily draw off worm tea when it accumulates, and put in a false bottom (with drainage holes to allow the worm tea to drain through) high enough up to allow for a one foot deep space for the bedding and worms, and you’d have a fine bin, I think. You can cover it with a piece of wood and put the bin up on a table or blocks so you can put a collection container under the hose bib. If I didn’t already have a working bin, I’d do this. You might come up with a better bin if you look at the various bins offered for sale and consider how you can make something similar.


  1. Thanks for the great information! I've been thinking for a long time about trying worm composting, but in the end I can never really think of an advantage over regular composting. Is there one? I guess you end up with a more concentrated nutrient, and it is a bit faster, but is it really worth the trouble?

    Related to this: our urban compost bucket filled up with maggots late last year. It seemed pretty revolting at first, but it actually smelled less and they were eating things down quickly. It turned out they were black soldier fly larvae, which are used commercially to compost pig manure, for example. The adults are very unlike regular house flies and are not pests at all. We learned to love them mostly because they kept the odor down, reduced the volume of compost quite quickly, and turned the pile from a static heap into an undulating mass! You can compost oily things or dairy, etc. with no problem when maggots are on your side!

    1. The main advantage I find to worm composting is the worm castings. I raise a lot of seedlings, including tomato and pepper seedlings that need extra fertility in order to grow well. When I used only garden compost in the seedling mix, these plants grew only very slowly. The tomatoes had the purplish cast that signifies too little phosphorus in the mix. When I added some worm castings to the mix, the tomatoes grew faster and had their usual color. Adding the worm castings also improved the mix for my container plants. If I weren't making my own mix for seedlings and container plants, I wouldn't bother with keeping worms; I'd just compost all our food scraps instead of allowing the worms to eat some of the food scraps.

  2. Hi Claire...

    New to your blog--came by way of Sharon's. You caught my eye because we live in the same general area--I'm across the river from you, and out in the farm country.

    We have lots of free range worms, lol..and I've been thinking about doing some bins...this was very helpful--thanks!

    I'll be back!!

  3. Hi I was wondering if I can gather worms from outside to add to my worm bin... I was just curious because it would be a great activity for my children.

    1. Hi Tabitha, you might be able to gather worms from outside to add to your bin, if they are the small red earthworms that live within a foot of the soil surface. If you try it, let us know if you are successful with them!

  4. & also is it okay to use night crawlers from the bait store and if not could you explain why

    1. As I understand it, night crawlers are distinct from the red worms that the bait store also sells. Night crawlers are much longer and live deeper in the soil, where the temperature is stable or nearly so year round. They are adapted to temperatures of 50-60F, most likely cooler than you can maintain year round in your house or even your basement. The red worms, on the other hand, can take warmer temperatures and are ideal for worm bins kept in the house or basement.

  5. It's only gardening and not some million dollar project that could empty your pockets. Not all of us are blessed with a green thumb, so there are bound to be hits and misses. 4 waste garden bags