Plastic Storage Bins

Plastic storage bins are easily converted to worm bins.  I recommend the Rubbermaid 50 gallon bin, which sells for under $20.  Many worm composting instructions show the use of a smaller bin, but unless it’s for

indoors & space is a consideration, larger size is preferable for two reasons:  1)  higher capacity (it can process more of your kitchen scraps), and 2) the larger bin provides more thermal mass, & if kept outdoors, is better able to survive winter temperatures. The dimensions of this bin are 42.7″ L x 21.4″ W x 18″ H.

Drainage

To keep the bin at the optimum moisture level, you’ll need to sprinkle water on it occasionally.   The excess needs to flow out the bottom.  You could just drill holes in the bottom, but there’s an easy way to collect the overflow:

Buy  2)  1/2″ PVC pipes the length of the bin, plus 3″.

Drill 3/16″ holes all along one side of the pipes.  If you drill along the writing on the pipe, it will keep your holes on one side, over the entire length.

Drill 2 holes in the bottom of the side of the bin, at one end, so that they can lay on the very bottom of the bin, and stick out the end.

Insert the pipes in these holes, & position them so the holes in the pipe face up.

Seal the holes in the bin (where the pipe goes thru) with silicon seal.  Glue them into a “T” so that it will keep the holes facing up, which is critical; it won’t drain otherwise.  The idea is that water will collect at the bottom & rise to the level of the holes, then flow into the pipe & out the end.

Aeration

Another important consideration in any bin is adequate air circulation.  Usually, the instructions are to just drill holes in the sides of the bin.  I recommend covering the bottom of your bin, as a first layer,  with 2″ - 3″ of gravel (approx 1/2″ rocks).  This will allow you to drill larger holes (1/2″) all around the bottom of the sides of the bin, and allow air flow throughout the entire bottom of the bin.

To the right is the completed bin, with temperature graph, spike thermometer, & plexiglass window, for an elementary school garden.

Wood Bin

Another good option is the bin made from plywood & 2×4’s, measuring roughly 2′ x 4′.  Its capacity is approx. 65 gal, about a third more volume than the plastic bin described above.  It’s very durable, and easy to attach foam board insulation for winterizing.  If you’re up for this wood project, here are the two best plans I’ve found:

http://www.seattletilth.org/learn/resources-1/compost/WormBinPlans.pdf/view

And more detailed plans with a very informative sheet:
http://www.co.whatcom.wa.us/publicworks/pdf/solidwaste/worm.pdf

Other Creative Solutions

There are other options for making  a worm bin.  You can use any sturdy container that has a favorable surface area to depth ratio, i.e. it is longer & wider than it is deep.  A 5-gallon bucket would not be a good choice for this reason.

Here’s a picture of an old kitchen sink I found.  I put approx. 1 quart of gravel over the bottom drain so it wouldn’t clog, and to deter who knows what from burrowing up into the bin.  There are no air holes in the side, but since it’s my second bin (for extra scraps); it’s an experiment to see how well it would work.