How to compost in an apartment: Everything you need to know

Compost is a nutrient-rich mixture of decayed organic matter (typically a combination of food scraps and plant material) that farmers and gardeners use as a natural fertilizer. Composting is the process of creating an environment with the right temperature, materials, and moisture levels for specific bacteria, insects, and/or fungi to thrive, so that they can quickly break down organic materials into finished compost.

Compost is essentially free fertilizer for plants. It helps maintain soil health, returning nutrients to the ground after your growing plants have depleted them. 

Some cities—like San Francisco—have municipal compost programs, where they collect compostable materials from residents and then process them in large facilities; the compost is then sold to farmers or donated to community gardens. 

If you don’t live somewhere with a city-wide composting program, you can make your own compost and use it in your garden or potted plants: succulents, herbs, or even vegetables in pots. If you’re a gardener, your compost system also gives you a place to put all the plant matter you’ll accumulate in your garden from pruning and weeding.

If you’re not a gardener, you may not reap the immediate benefits of composting, but you’ll know that you’re contributing to a healthier environment by reducing food waste and improving soil health. You’ll also have the knowledge that somewhere, a farmer is using your food scraps to grow food that you might eat someday.

According to the Food and Agriculture Organization of the United Nations, one-third of the world’s food is lost or wasted. Some of this happens at the supply-chain and retail levels, but home food waste is still a big problem. 

In 2013, the U.S. The Environmental Protection Agency reported that the largest component of residential landfill-bound garbage (a whopping 28 percent) consisted of food scraps and yard trimmings. This organic matter, which can break down in a matter of weeks under ideal conditions, can take decades to decompose in a closed-off landfill, all the while releasing methane, a greenhouse gas.

Luckily, there’s a simple solution to shrink landfills, reduce greenhouse gas emissions, and support healthy soil: compost.

If you have an outdoor space, such as a backyard or patio, you can start your own closed-loop compost system, meaning that any food or yard waste you generate will be recycled back into your own garden. There are two main ways to do this: open-bin and closed-bin. 

Open-bin systems, also known as compost piles, are exposed to the air. Open-bin systems usually consist of three bins: An active pile to which you regularly add fresh organic matter; a decomposing pile; and a pile of finished compost. Turn your decomposing pile every one to two weeks, using a compost cork, pitchfork, or similar tool to fluff up the compost and move it around.

Closed-bin systems have a lid, which prevents pests from entering your compost bin. Closed-bin systems need to be aerated frequently, so they’re often designed in the shape of  wheels or tumblers that need to be turned daily. 

Depending on your compost system, your compost will be ready in as little as three months and up to one year.  (Compost systems with more “greens,” vermicomposting, and tumbler systems tend to be faster than traditional compost pits. To speed up your compost, chop your materials into tiny pieces.) 

To test if your compost is ready, put it in a sealed plastic bag for a few days. If the bag smells rotten when you open it, put it back in the bin and let the compost continue to work.

If you don’t have a garden, or if you garden in a very small space, you can still compost. The easiest way to do this is to save your compost at home and bring it to another facility. Some cities offer compost pickup along with regular trash and recycling pickup. If your city doesn’t offer composting, there may be a farmer’s market, community garden, or other facility in your neighborhood that would love to take your food scraps. 

If you prefer to compost at home but have limited space, a worm bin is a great option. Here’s how it works: You give the worms food and plant scraps, which they turn into worm castings (yes, poop). Worms don’t require a lot of room, and their castings provide an easy-to-work-with, potent natural fertilizer.

Vermicomposting, or composting with the help of earthworms, is a great option for indoor composting since a worm bin doesn’t take up too much space and worms prefer a temperature of 55–80°F. (You can also use a worm bin outside, in a shaded area. Just make sure to insulate the worm bin in the winter if you live in a cold climate.) 

You can make your own worm bin with a 14-gallon plastic lidded bin and a drill. Here’s how:

1. Drill holes. 

Drill holes near the top of the bin and in the lid to allow oxygen to enter, and in the base for drainage. (You can use a second lid as a drainage tray to collect runoff.) To prevent pests, you can secure small mesh screens in front of the holes with duct tape. 

2. Make the bedding. 

Bedding absorbs moisture in a worm bin and prevents odors. Make the bedding by tearing black-and-white newspaper into 1-inch strips. Fill your bin up two-thirds of the way with newspaper strips. Use your hands to fluff up the strips and lightly moisten with a spray bottle as you go.

3. Add worms. 

The specific type of earthworms used in vermicomposting are called red wigglers (Eisenia fetida), a species that can eat half their body weight in food scraps in one day. You can find red wigglers at a garden shop or online. Add at least one pound of red wigglers to your worm bin.

4. Feed the worms. 

Feed your worms small food scraps (no meat, dairy, alcohol, or spicy or salty foods) daily or weekly. (One pound of worms can eat about 3.5 pounds of food scraps in a week.) Each time you feed your worms, gently push the bedding to one side and place the food in a new spot. This will allow you to see how quickly the worms eat, and how much you can add at a time. Cover food scraps with more newspaper to prevent odors and pests.

5. Harvest finished compost. 

In three to six months, you’ll have finished compost, which should look like dark soil. When this happens, push all of the compost to one side of the bin. Add new bedding to the other half of the bin. Wait one month for all the worms to move to fresh bedding, adding food to the fresh side. Remove the (mostly worm-free) compost, sift, and return any worms or anything else that didn’t break down back to the worm bin.

The organic matter used in a compost pile is typically labeled into one of two somewhat misleading categories: browns and greens. To check whether your compost has the right balance of browns and greens, smell it. Compost with too many greens can have a sour smell, and compost with too many browns won’t smell like anything. A balanced compost pile will have a sweet, funky smell.

Nitrogen-rich “greens” are typically moist and should be covered with a layer of “browns” to prevent pests from entering your pile. (Many home composters like to keep a large bag of dried leaves or other browns handy to add to their pile every time they add food scraps.) Greens include:

• Fruit and vegetable scraps (note large amounts of citrus fruit is not good for a worm bin)

• Human hair and pet fur

• Coffee grounds and tea bags (with staples removed)

• Fresh grass clippings and garden trimmings

Carbon-rich “browns” should be chopped into small pieces, and require the moisture of “greens” to break down. Browns include:

• Dry plant material such as dried leaves and flowers

• Sawdust, straw, and woodchips

• Newspaper and food-soiled napkins and paper towels

• Egg shells (To add eggshells to a home compost system, rinse the egg shells to remove any egg white lingering around the shell.)

If you’re bringing your compost to another facility, such as a community garden, check to see which products they accept; each facility is different. In general, only industrial systems can handle:

• Meat and dairy products, bread, and food cooked in oil, which can attract pests to your home compost. 

• Plant-based plastics and plastics labeled “compostable” or “biodegradable.”

• Weeds or diseased plants. Adding weeds or diseased plants to your compost bin can cause those same weeds and diseases to show up in your garden next season.

Unless you cook in an outdoor kitchen, you probably need a place to store your food scraps until it’s time to bring them to the compost pile. You can store food scraps in an airtight container at room temperature and there are many compost pails designed for this purpose, some with odor-preventing features. 

The best way to prevent smells and bugs, however, is to keep your food scraps in the freezer. Choose a large plastic bag, jar, or other freezer-safe container and add your scraps to it throughout the week. When the container is full, add the frozen scraps to your compost pile. 

If you’re saving food scraps for a worm bin, you’ll have to defrost them before feeding the worms. In this case it makes more sense to keep the scraps on the countertop.

Transporting compost in a sturdy reusable container is the best way to make sure the compost won’t leak on your way to the compost pile. 

Compost is a natural fertilizer that will help improve the nutrient content of your soil. When preparing beds for planting, add 1–2 inches of compost to the top of your soil and work it into the top 3–5 inches of the bed. Throughout the growing season, apply half an inch of compost monthly around the base of heavy-feeding plants like tomatoes and squash. 

For potted plants, which require more drainage than plants in the ground, add an inch of compost twice a year.

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