Making a Worm Compost Bin

Equipment Needed

Two Rubbermaid ‘Roughneck’ opaque storage bins:  14 gal/53L (24 x 16 x12.5 in)

worm-bin-2Hand drill & two drill bits size 5/64” & 3/16”

½ strips of newspaper (avoid machine shredded paper & glossy coated colored advertisements)

A couple whole newspaper sheets

Small amount of soil

Redworms, Eisenia fetida (not earthworms or night crawlers)

Vegetable scrapes (no meat)

Making the Bins

You will be setting one bin inside of the other. The outside or bottom container has no holes drilled in it. It catches the worm casting liquid that drain from the top inset bin.

You will need to aerate the first container (Bin #1) that sets inside the bin without the holes (Bin #2). Use a drill bit size 5/64 in. (which keeps flies out & worms in) and drill about 300 holes. If you like you can get pretty fancy with a design! Also, drill several holes near the top two inches of the container. Using the same size drill bit drill holes around the edge of the container lid. These holes can be spaced quite a bit further apart. Tip – drill holes close to top edge or holes are covered when you double stack the bins.

worm-bin-5Now for the bottom of Bin #1 – the inside container. You need only a few holes for bottom drainage but they need to be slightly larger than the holes on the side and the lid. Using a 3/16# bit, drill one row of around the outside edge of the bottom (between the side and the center rectangle markings) spacing a row of holes about three inches apart.

Adding the Worms

First, insert the Bin #1 into Bin #2. (You only need one lid – the one with the drilled holes.)

Use only redworms. Earthworms need to tunnel and will die in the confines of the bin.

Place a sheet or two of newspaper on the bottom of Bin #1.

Add a “pile” of worms, which usually are already in a mix of soil & droppings for ease in transporting. If you like you can add a little more soil, but I haven’t found it particularly necessary.

Add raw vegetable scrapes. Limit the quantity some until your worm population multiplies or you run the risk of “overfeeding” and they can’t keep up with the amount of food. However, not enough food will eventually deplete your worm colony. The more they eat the more they multiple. If you neglect them and do not feed them their numbers dramatically decrease. Use your own judgment. You’ll figure out what works best.

Keep the worms covered with strips of newspaper. I suggest you lightly dampen the paper when getting started, e.g. sprinkle a little water over the top of the strips of paper. Once you have quite a community of worms the moisture in the bin seems to handle it nicely without adding any extra moisture to the paper.

Occasionally, I like to sprinkle ground up eggshells to help their gizzards. Coffee grounds work too.

worm-bin-4Feeding the Worms

Raw vegetable scrapes. If you tossed in the eye of potatoes or the end tops of carrots you will likely find growing in your bin! They’re easy to pick out. Avoid too much citrus. Evidently, the acid can aggravate the worms. I’m told the worms love banana peels. I usually chop the peels into one inch or so pieces just to help the process along faster. They do seem to disappear fast! Do not add meat. I don’t add breads either.

Worm castings will deepen in the bin like rich gold. An added bonus will be the liquid collected in the bottom of Bin #2. You can top dress houseplants with the castings and/or dilute the liquid and use as a liquid fertilizer. I dilute the liquid casting to about 1 part casting liquid to 5 parts water. The castings used as a top dressing to indoor plants are effective against white flies.

worm-bin-3Separating the Worms from the Castings

After a couple of months or so (I’ve actually gone 6 or 7 months), depending on how much food and the accumulation of castings, you will need to separate the worms from the castings and start a fresh bin. This is a bit of a messy process but well worth it. You may want to use rubber or those disposable latex gloves. Literally place mounds of castings on a piece of plastic. It helps to set light over the piles because the worms don’t like it and head for the bottom of the mounds. You can then “scrape” off the wormless top and save for future soil amendments. Just keep doing that until you’re left with mostly wiggly worms. Place the worms back in a freshened bin and you’re ready to go again.

Another method (but slower) is to move most of the castings to one side in the bin and place the food to the other side. The worms gradually migrate to that area with food leaving mostly the castings on the other side. I’ve found it to be on the slow side and not all worms migrate…but it’s worth a try if that’s you’re only means or preference for separating the worms from the castings.

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