What to Compost - Creating the Best Compost Ratio
Tips For What to Put in a Compost and What to Leave Out
If you’ve ever wondered what to put in a compost bin or pile, look no further. Here’s ecolife’s definitive guide to what things you can put in your compost to achieve a healthy, well-balanced system that produces low-hassle, beautifully mature compost.
What can I compost?
Every compost is made up of the same two key ingredients:
- Greens are those materials that are high in nitrogen. These act as a source of protein for microbes that do much of the work in your compost pile or bin.
- Browns provide the carbon to the pile, which is the energy source needed by microbes.
Want to know what goes into each category? Let’s break it down for you:
Greens (high-nitrogen, fresh)
Browns (high-carbon, dried)
Coffee grounds (including paper filters)
Cotton or wool clothing (torn into strips)
Egg shells (washed and crushed)
Dried grass, twigs, and leaves
Green leaves and twigs (nothing too big)
Hair (human or pet)
Non-chemically treated paper
Leaves and stalks from garden plants
Raw fruits and vegetable scraps
Seaweed and kelp
Pine needles (dry)
Tea bags and loose tea leaves
Salt marsh hay
Weeds (only those that have not gone to seed)
Wood ash (see cautions below)
Make it easy on yourself by thinking of greens as “fresh” and browns as “dried.” Keeping this distinction clear in your mind will help you as you evaluate what to add to your compost and what to leave out.
The ideal compost ratio
Adding materials to your compost is like whipping up a batch of cookies. You’ll want to ensure that you have the right compost ratios so that you avoid problems like odors, pests, and the like. The simplest method for determining the correct compost ratio is to maintain a 2:1 ratio of browns to greens. That means if you’re working with grasses and leaves, add about 66% leaves and 33% fresh grass clippings. You’ll need to add these materials to your compost in layers, alternating between fresh/wet ingredients and dead/dry ingredients. For a more in-depth discussion of how to achieve an ideal compost ratio, check out the Master Compsoter guide to preparing compost materials.
What should I leave out of my compost?
Of course, we’ve hinted that there are many types of materials that you should not generally put into your compost. Although some of these are controversial, you’ll find that keeping these out of your compost pile or bin will help to maintain a safe, pest-free, low-maintenance compost system. Here goes:
- Wood ash: This material can increase alkalinity of your compost so should be added in small quantities at a time. Keep the quantity of wood ash added no more than 2 gallons for every 3’x3’x3’ of compost volume.
- Coal ash: These contain sulfur and iron in quantities that could be damaging to plants once the compost is added to your garden or landscape so should be avoided.
- Paper with colored printing: Many inks (including those used by some newspaper companies) contain heavy metals that will not be healthy for your plants or you should you choose to put your compost on a veggie garden. Ask your local newspaper what kinds of inks they use before adding it to your bin.
- Diseased plants: Most plant diseases are difficult to kill unless you can achieve an extremely high-temperature compost pile. Living diseases that are transferred to a garden through compost will go on to infect other plants, so keep clippings and prunings from sick plants out of your bin or pile.
- Weeds gone to seed: Seeds from weeds that have already gone to seed can survive even the hottest compost piles, spreading their pesky plants throughout your landscape with the compost. So add weeds only if they haven’t gone to seed.
- Meat, fish, bones, dairy, and fats: Not only will these materials attract pests and rodents and contribute to odor problems, they can also overheat your compost pile and should be avoided.
- Animal and human feces: Manure from any animal can contain pathogens that are difficult if not impossible to kill in a compost pile. While composting feces is a great way to reduce your carbon footprint, if you plan to use your compost to grow food crops, it is recommended that you compost these materials in a separate compost system.
- Chemically-treated material: In particular, things like conventionally-grown peaches and bananas as well as orange rinds will be high in pesticide residues which can get into your own organic garden when the compost is applied. Caution is recommended for these things as a result. Likewise with lawn and garden trimmings if you use herbicides and pesticides on them.
Can I put that in my compost?
If you’ve got a burning question about what you can add to your compost pile, you may be able to find the answer you’re looking for with these in-depth resources on composting:
- Can I Compost This? - New Brunswick’s Depart of Environment
- Compost Ingredients - Master Composter
- Composting 101 - What not to use
- Composting and Mulching: A Guide to Managing Organic Yard Wastes - University of Minnesota
- Composting Tutorial - Florida’s Online Composting Center