What To Look For In Worm Compost Bins
When starting your worm composting, or building your own worm compost bins, you need to decide what kind of bin to use to house your worms. Many factors come into play when determining what type of bin is best suited to your needs.
Let’s start by eliminating materials that should NOT be used as compost bins:
Do NOT use Styrofoam. Styrofoam contains toxins that will seep into the compost and turn the contents into a toxic environment. The compost will be destroyed before it’s even started. Using Styrofoam would be self-defeating as it isn’t eco-friendly, going against everything we’re trying to accomplish by worm composting.
Do NOT use metal. Metal is a heat conductor which will complicate controlling the environment’s temperature. The bin’s temperature is critical to the worm’s existence. Their living conditions require a temperature ranging between 40° and 80° for the worm’s survival, however, keeping the temperature between 50° and 70° will increase production since the worms work best in that range.
Metal is prone to rusting and we definitely don’t want any rust in our compost. Also, metal is highly likely to release heavy metals into our compost…not what we want in our final product. Do NOT use cardboard. Using cardboard isn’t hazardous like metal and Styrofoam, but it just isn’t practical. Cardboard isn’t sturdy enough for the task at hand, especially since the worm bin needs to contain adequate moisture for the worms. Wet cardboard is useless unless you’re using it as the worm’s bedding, in which case you’d have to use very small pieces.
Do NOT use glass. There are many reasons not to use glass, but there are two key reasons. Your compost bin is going to need ventilation and drainage, which means the bottom and the sides of your container are going to need holes in them. And, worms are photophobic. They don’t like sunlight, or any light for that matter. It’s suggested to use a bin that is dark in color, definitely not one that’s transparent.
IS YOUR BIN GOING TO BE INDOORS OR OUTDOORS?
The location of your bin is going to determine its size and what it’s made of. You also want to consider if it’s going to mobile or stationary. If your bin is going to be kept inside then it will most likely need to be moved when it’s time to harvest your compost.
Outside bins can be stationary or mobile. If the bin is stationary, then a bin can be built right into the ground using bricks. You want to be sure, though, that the ground has adequate drainage and if you aren’t sure, you should line the bottom of your enclosure with rocks, just as you would when potting a plant with no drain holes.
All other containers will be the same as those you can use indoors. The only thing that may vary is the size. Obviously, it’s more practical to keep a large bin outside and to consider how far you’re going to have to move it when you do. Most likely, the bigger the bin is, the heavier it will be.
For inside bins, it’s best to limit your size to fit the space where you’re going to keep it, so you’ll probably want a compact bin. The most highly recommended bins are made of wood or plastic...
Either way, there are ‘must haves’ such as holes for drainage and holes for ventilation. They also need to have a lid that is either a material that is breathable or a lid with holes in it. A good place to keep your inside bin is in the basement where it’s already dark and damp.
Plastic bins are very practical. They’re readily purchased at any dept. store, hardware store and even the grocery store or dollar store. It most likely comes with a lid when you buy it. You’ll have to drill holes in the bottom so excess water can drain out of it and you’ll want holes on the sides and in the lid for ventilation.
You can recycle plastic containers that you already have such as dishpans, tubs, etc. An old recycling bin is actually a perfect size container. Plastic bins need more drainage than wood bins.
Wood bins are even more practical, although you may have to be more creative when coming up with a lid for it. Wood is natural, and it’s nice to keep the whole environment for the worms and your compost natural.
There are also a lot of options for recycling wood that’s already in your home like old drawers, wine boxes, etc. Feel free to get creative. Wood has better insulation and is absorbent. This helps eliminate many potential problems such as rotting food and dying worms. You’ll also have to drill holes in the bottom and sides.
To determine the surface area of the bin, you’ll need to collect your food waste for a week and then weigh it. Your ideal surface area will be one sq. foot per lb. of food waste.
For outside bins a solid lid is recommended. A solid lid will keep out most of the rain (you may want to put it under some sort of sheltered area because the vent holes you make in the lid aren’t magic ‘let the air in and keep the rain out’ holes). The lid will also help keep the critters and pests out of your bin. Since you’re working with food scraps, it’s very likely that you’ll attract some uninvited guests.
A good material to use as a lid on an inside bin is burlap, but other materials will work too. The lid will minimize any problems with fruit flies and help keep the moisture from evaporating as quickly. It also prevents any odor from escaping (which there should be little to none if you’re doing everything properly). For both inside and outside bins, the lid is going to block any light from entering.
You may want to have a barrier in the middle of your bin depending on the method you want to use for harvesting. By adding a barrier, which will divide your bin in half, harvesting will be much simpler. See the harvesting section for details.
You’ll need a pan to keep underneath your bin to collect any drainage you may have.
TIP: Once you’ve collected the drainage, it can (and should) be used as a liquid fertilizer for your houseplants.