How to Compost
There are several designs of compost bins commercially available or that could be built, all of which, when properly maintained, would compost kitchen and yard scraps without pest or odor issues. However, it is possible to DIY a compost bin from easily available materials. The method below is that which is used by gardeners at the Boca Raton Community Garden.
Compost Bin Options
DIY simple two-bin system
There are many ways to compost. The Boca Raton Community Garden has a simple method for gardeners to make compost for their vegetable plot. These instructions adopt that method for home use. Although the method is simple and economical, it requires attention and effort.
- Two 20-gallon plastic garbage cans. (larger bins are difficult to turn contents)
- One short shovel (27 inches)
From here on out the garbage cans will be referred to as compost bins.
- Drill holes in each bin (5/16 inch holes are good).
- Bottom: Drill one hole in the center and six others spaced around the bottom of the bin.
- Sides: Drill one row of holes around the bin at the height of eight inches from the bottom with each hole eight inches apart. Drill a second row of holes around the bin at the height of sixteen inches from the bottom with each hole eight inches apart.
- DO NOT drill holes in the lid
- Collect your browns and greens for your initial layers. (More information on browns and greens below)
- Start with one layer (6 to 8 inches) of browns) in the bottom of one bin. Then make a layer of the same depth of greens.
- As you add material, keep alternating layers until the bin is three quarters full. End with a layer of browns to control odor.
- Let the bin sit for a few days. The microbes will start working to break the contents down.
- After a few days, start mixing the contents with your shovel or turning the entire contents over into your second bin. Mixing and turning aerates the contents and creates a feeding frenzy with the microbes that speeds your compost along.
- Most of the inhabitants of your compost are microscopic but some you will be able to see. Bugs are an important part of a compost system! They are helping to break your material down.*
- If the pile becomes too wet and/or smells, add more browns.
- If the pile becomes too dry, add more greens.
- The pile will start to break down and you can add more materials to it, but at some point you will want to stop adding more material and simply mix and turn. You can turn over the compost between the two bins. At this point, start collecting material to start a new bin.
- When the compost looks and feels like dark, crumbly soil (after about 8 weeks) and none of the waste is recognizable – it is done!
To use compost:
Dig the compost in around your plants or put it in new planting holes. Compost can be used for indoor potted plants.
Worm composting (vermiculture) is a composting process using various species of worms.
The process produces worm castings which are the material left behind after the worms eat and digest kitchen scraps and other organic matter. The worm castings are then harvested and can be applied to the garden. The most significant benefit is that the nutrients in worm castings are easily absorbed by the roots of the plants. Castings contain bacteria and microbes that help plants become more resistant to disease.
The Boca Raton Community Garden has a vermiculture project consisting of five large bins on pallets. Bins were prepared with shredded newspaper, compost and soil, fruit and veggie waste, coffee grounds, rabbit bedding and filtered water. Approximately one thousand worms or different species were purchased and added to one end of each 48-inch long bin. One bin contains Alabama Jumpers, one has European Night Crawlers and three bins have Red Wigglers, the most common worm composting species.
After approximately two months, food is moved towards the center of the bin. The worms gradually migrate to the new food position. Any remaining worms can be screened out and repositioned to where the food is placed. The program continues in the same manner throughout the length of each bin providing a simple method for obtaining worm castings.
Compost Cheat Sheet
What to add to your compost bin
Examples of GREENS (Nitrogen)
Vegetable scraps, fruit scraps, garden trimmings, grass clippings (NO pesticides*), seaweed (wash off salt), coffee grounds.
Examples of BROWNS (Carbon)
Paper towels, shredded newspaper, shredded plain cardboard, sawdust, straw, hay.
You can also add:
Eggshells (microwave one minute before adding) and bread.
DO NOT ADD
Dog and cat droppings, meat, fish, bones, oils, dairy, diseased plant material, woody plant material, inorganic materials (e.g. plastics, metals, etc.), fallen dried leaves/pine needles (they will not break down fast enough).
How to trouble shoot a smelly compost bin?
A compost bin may start to smell or attract pests for a variety of reasons. The three most common are also very easy to fix.
- The bin is too wet. A wet compost bin makes it difficult for microbes to break down the food and vegetative scraps, leading to odors. To fix this you can add more browns which are typically drier than the greens. Turning the pile helps to aerate it and dry it out. Finally, make sure you bin is not leaking or letting in too much rain water.
- There are too many greens. A bin with too many greens is also often a bin that is too wet. Fix this issue by adding in more browns and mixing it well.
- Adding meats, fats, or dairy. While the listed items are organic and technically can be composted, to do so in a residential area is asking for smell and interested animals. Make sure that you are carefully selecting what goes into the bin and excluding meats, fats, and dairy.
REMEMBER: Follow the basic guidelines, use your best judgment, be observant of the results and adjust as necessary. Don’t worry too much about doing it perfectly!
*Do not put any material in your bin that contain pesticides. The creatures living in your bins are what break the materials down in to soil, pesticides can harm them negatively impacting the composting process.