Building and maintaining outdoor compost bins is not difficult. Whether you build your own or purchase an easy assembly system, you already have most of the essential ingredients for success: food scraps, a little dirt, some leaves or grass clippings, water and air. It’s easy to learn and apply the essential steps to successful composting.
Just as with all of our garden planning advice, start by asking yourself three questions:
What do I want to get out of this? (recycle waste, create potting soil, etc.)
What are my physical constraints? (space available, raw materials, climate)
How much time and money can I expend, and when do I need the compost?
The following compost bins are organized from simplest and cheapest to more time consuming (to build) and most expensive.
Compost Heap
If you have space available away from your home, such as behind a tree stand or at a woods line, this is your completely free method. To get some good internal composting temperatures going, build your food and yard waste pile to about 5 ft/1.5 m wide by 3 ft/1 m tall.
You can turn it occasionally with a shovel or pitchfork to introduce air. This will speed the process, as the microorganisms that do the composting thrive with more air. If you decide not to turn it, you should either omit fruit scraps from the heap or add some dirt on them when you do add them, as fruit may attract animals.
Wire Mesh Bins
To make a 3 ft/1 m diameter compost bin, use 10 ft/3 m of 3 ft/1 m tall galvanized chicken wire. Set the roll upright and join the ends to form a circle using some coated electrical wire or the ends of the chicken wire roll. Adding four wooden or metal posts inside the circle enhances strength. Place a plywood board or snow saucer on top so you control the compost bin’s moisture level. To remove composted material, bend open the bottom of the cage.
Fence Composting Bins
The easiest way to build this is with snow fence, a roll of which you may purchase. Support posts on the inside are helpful, as this type of fence will not stand well on its own until about half full. You will need 13 ft/4 m of fencing to make a 3 ft/1 m per side recangular enclosure. If you build a rectangle, it is best to join the ends—where you will open it to remove humus later—in the middle of one side rather than on a corner.
You can make a sturdier and better looking version with picket fence sections. For this you will have to include a door on one side to remove the composted humus from the bottom of the bin.
Pre-Made Compost Bins
These easy and efficient systems are round or rectangular enclosures made of rigid green (for warmer climates) or black (for cooler climates) recycled plastic. The color enhances solar heat production. They snap together and are more attractive than a heap, chicken wire or fence-made version. They are available for under $150.
Key features are plentiful air holes, at least two sliding trap doors at the bottom for humus removal, and a clip or other system to keep the lid shut. If the unit has these ingredients, feel free to buy based on styling, color preference, warranty and price.
A less expensive alternative are the circular flexible nylon compost bin systems with ventilation holes. These “ready to unroll and stand up” bins are essentially a substitute for chicken wire, but without chicken wire’s weight, durability, rigidity and low cost. The lightweight plastic stakes for holding the bin in place can make for too floppy a structure, particularly in windy conditions.
Compost Tumbler
The tumblers are the most expensive compost bin systems. They are constructed of heavy duty plastic or steel, and have either a hand crank mechanism for turning the composting material, or the drum itself will flip on a pivot hinge.
This is an advantage over turning your pile with a pitchfork or pile turning tool. Another plus is that compost tumblers have receptacles to catch “compost tea,” the nutrient-rich liquid that runs off during compost formation, and which makes great indoor or landscape plant food. The oft-stated claim of making compost in a month or so may be accurate in perfect environmental conditions, but results vary.
The disadvantage of a tumbler other than price is that unless you spend $500 or more to get a two chambered system, you can only work on one batch at a time. This means you have to store food and yard waste somewhere until the tumbler is available to refill. The capacity of most tumblers is also less than stationary compost bins, unless you are willing to spend the money for a larger system.
Handy Accessories
You can do without these items. However, the kitchen counter food scrap containers have scent limiting filters, their lids fit tightly to discourage fruit flies in Summer, and they look good--possibly avoiding some disputes over "garbage" on the counter.
The aerators are important for turning the heap in non-tumbler systems. They are much easier to use than a shovel, hoe or pitchfork, as they insert straight down. You should strongly consider buying one if you have any concerns for your back.
