I call this page "practical" worm composting (or vermicomposting) because it details my actual experiences/experiments, in addition to giving general information. The purpose was to get rid of yet another source of odor in the home, my kitchen garbage. My garbage can now contains only non-recyclable, non-food material and equates to one small grocery bag every three to four weeks. As a side benefit I have wonderful worm castings for feeding the plants. A special challenge is that I wanted this to be an outdoor worm composter. In a climate (Ottawa, Ontario, Canada) which ranges from -15C (5F) to 30C (90F), that can be difficult. The page on temperature control details much of my efforts towards this.
My numerous worm bin experiments
The rule of thumb for bin size is to have 1 square foot of bin surface area for each pound of waste/food per week. Using my digital scale and samples of food I estimated I produce 3lbs (3 pounds, lb is shorthand for pound) of waste per week (it later turned out to be about 5lbs.) So I would need 3 square feet of bin surface area. The height of the bin should be 8" to 12", regardless of the surface area so that didn't play into these calculations.
The rule of thumb for quantity of worms needed is to use 2lbs of worms for every 1lb of waste per day. So 3lbs of waste per week divided by 7 days gives 0.43lbs of waste per day. To get the number of worms, just multiply waste pounds per day times 2 (since it's 2lbs worms for every 1lb waste.) So I needed 0.86lbs of worms or roughly 1lb.
But given my local source, red wiggler worms cost $30 CDN ($27 US) for a 1/2lb and I wanted to keep costs down so I ordered 1/2lb of worms and would let them procreate to get what I ultimately needed. On May 23, 2006 I orderd them without being given a specific arrival date.
I was in the middle of building a wooden bin but unfortunately it wasn't ready by the time the worms arrived on May 27, 2006 so I had to scramble and whip up a temporary bin (black plastic bin.) Its surface area measured 1.5 square feet, suitable for 1.5lbs or waste per week so I'd have to give it only every 2nd day's waste.
My goal was to do the composting outdoors. Worms survive best in the temperature range 4C-27C (40F-80F). I could insulate the bin for winter, where it can get as cold as -15C (5F). But I would have trouble with the summer where it can get as hot as 32C (90F). So I would start with a wooden bin which at least had better insulation value over plastic.
The bin was completed on June 12, 2006 and I moved the contents from the black bin to this new wooden bin. By June 24, 2006 there were plenty of worms in all areas. By July 2, 2006, after making some modifications, I was ready to put the bin outdoors.
Of course, once it was outdoors, I started having to worry about the temperature inside the bin where the worms live. In summer it is hot (30C (90F)) and in winter it is cold (-15C (5F)) so I took seasonally appropriate steps such as burying the worm composting bin, adding tubing to get geothermal cooling/heating, adding insulation and others.
Things found in my bin