Worm Compost Bin (small)

This ‘fun’ craft was also a useful one: a small bin for worms to compost kitchen scraps. Different from a regular compost bin in that the end product will be ‘worm casings’ (worm poop): a dark, heavy, nutrient-rich compost (4:1 soil/casings) versus ‘regular’ lightweight compost (2:1 soil/compost), which is a product of natural products breaking down (grass, leaves, food scraps etc). Both are good additions to the soil of my plants.

All the DIY worm bins on the internet were large, and quite frankly, I don’t want 50lbs of worms, casings, bedding, food scraps stored under my kitchen sink!
The first one I made from quart yogurt containers but decided that was too small. It needs to produce enough worm castings for my herbs and potted veggies but not so much I’m overwhelmed or lugging huge tote bins around. Enter plastic coffee cans… perfect size for my needs!

Worm bins work best when there are two connected, no matter the size, at least for me and those who want the system to be more hands off. Here’s why:

One bin – every month or whenever the bin fills with castings, you spread out plastic, dump the bin on it and pick out the worms to put back in the bin with new bedding (shredded damp cardboard and paper, a little compost or soil, kitchen scraps – no meats/fats/dairy, just fruits and veggies, though very limited amounts of grains and breads are ok).
You can also make mounds of the castings on the plastic and scoop off the top of the mounds as the worms work their way down to the bottom of the mounds (they don’t like light). Lots of mess and time.

Two bins connected – feed the worms in one bin, when it’s ready to harvest, begin feeding the worms in the other bin (create new ‘bed’ in 2nd bin with damp cardboard/paper, soil/compost, food). The worms naturally move over to the 2nd bin with no hands on from you. Harvest the 1st bin after the worms have moved, approx. a week after you began feeding in the 2nd bin.

If you need help making your own bins and have questions about this specific setup I would be glad to help. My design is extremely simple but not sure if the pics are easy to understand.

I took 2 Folgers coffee cans and attached them together at the grip type handles. I plan to make another set from Maxwell House cans, those will be attached side wall to side wall since the handles are real handles.

Measure from the bottom up approx. 2.5″ and mark the exact center on each plastic can. Since you’re dealing with connecting side to side and measuring from bottom up, 2 cans of different sizes can be used, though I wouldn’t suggest too much difference since each side needs to hold approx. the same amount of worms comfortably but a small difference is fine.

My cans are different by “35 cups” of brewed coffee but the actual size difference is very minimal (a couple cups of grounds?). You’ll see in the photo above the 1st can is slightly more tall than the 2nd can.

These are photos of the connector used to connect the cans. It’s a hose repair connector: if you have a hose that gets cut in the middle you can put the hose back together. I had this on hand, didn’t want to buy anything additional, but you can use whatever works best for you (I won’t be able to help you with something different as I have no experience with other options).

This connector is put through a hole in the side of each of the cans, then put a small piece of hose (approx. 1″) over each side of the connector inside the cans so the clamp has something to hold on to tightly. Put the clamps over the hose piece on each side, inside the cans.

The hole in each can, just a little over 1/2″, were drilled with a Dremel but a drill bit could be used to hollow it out too. Just err on the side of too small rather than too big; you can always force the connector through the hole if it’s too tight but if the hole is too large then you would have to seal it somehow.

In the lid of one of the cans I drilled 17 – 1/4″ holes (place them randomly, you may end up with more/less holes). The holes allow air flow, so excess moisture can evaporate. There must be dampness in the bins, but not wet. You want a little condensation on the inside of the lid but not dripping.
You can poke small holes in the bottom of one or both of the cans; I chose to do only one can so I could see just how much water added was too much. It came out the holes in the bottom much more quickly than I thought so add very little water!
Make the holes in the bottom very small, not large enough for the worms to escape but enough to allow moisture to drain. Use an icepick or a phillips screwdriver with a hammer to poke very small holes from the inside to the outside then cut the sharp points with a utility knife.

When a can/bin is ready to harvest, put new bedding and food in the 2nd bin; begin feeding only in that bin. After the worms have moved to the second bin, rotate the cans (see photo), holding upright the can with the worms while rotating the 2nd bin upside down to dump it out.

As you can see from the photo, I have a tray under the bin with holes in bottom to catch the run off. I used a plastic tray already here from a package of 6 sandwich pockets because one side is rounded and fits the coffee can perfectly, the other side is square. There’s a small sliver of space between the 2 bins because of the hose connector; the tray slides perfectly up into this tiny gap.

Leave your bin set up for at least a few days, up to a week or two, before adding your composting worms. This gives the food scraps a chance to begin breaking down so the worms will have bacteria to eat when they’re added.
Scientific name for composting worms: Eisenia fetida, although it’s larger cousin, Eisenia hortensis a.k.a. the ‘European Nightcrawler’ is used as well (fishing worms as well as composters).

As far as feeding your worms, even though we think of the cardboard and paper as bedding, the worms use it as bedding and food. Make sure to add plenty of ‘brown’ additions when you add food scraps. Pretty much all fruits and veggies can be fed to your worms. Don’t give them citrus, or limit it to very small amounts; they don’t really care for citrus, or onions. Grains and bread should be limited also.

In ideal conditions your worms will breed and double in quantity every 2-3 months. Ideal conditions are damp, cool, dark and quiet environment: ideal temp is 55F-77F but they tolerate a wider range of temps, they’ll just go dormat; pH of around 7, avoid citrus which can make the environment too acidic; feed plenty of ‘greens’ and ‘browns’, they can eat their own weight in just a couple days. Allowing the food scraps to break down before adding them to the bin helps the worms process it faster. The scraps can be left in a container to break down or frozen, thawed and the mushy scraps fed to your worms once a week.

I hope the info here gives you enough to get started but if you want to go more in depth there are plenty of websites with valuable information regarding care and feeding of composting worms: redwormcomposting.com is my favorite. Do a search and learn all you can before setting up bins or buying worms.
Good luck on your venture!


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