A Beginner's Guide to Composting, According to Experts

Composting is a secret weapon for gardeners—it gives food scraps and other natural waste a second life while serving as fuel for healthy plants. Plus, creating it is actually quite simple. To make compost, all you need to do is compile organic matter—think food scraps, leaves, grass clippings, and coffee grounds—and let it decompose with the help of water, oxygen, and organisms like worms and fungi. The process breaks down the biodegradable materials to make a soil treatment packed with moisture and nutrients, which you can then administer to your plants.

This system is a free and easy way to turn organic waste into something useful, thus decreasing trash pickups and landfill usage. And getting started doesn't necessarily require any special equipment. By following a few simple guidelines and building or buying a compost bin, you can begin your composting journey.

What Is Compost?

Composting is a controlled, aerobic process that converts organic materials into a nutrient-rich soil amendment through natural decomposition. Microorganisms feed on the materials added to the compost pile, using carbon and nitrogen to grow and reproduce, water to digest materials, and oxygen to breathe.

Benefits of Composting

Composting has a myriad of benefits for your plants and soil.

Improves Soil Health

The organic matter that compost is made out of acts as food for fungi, bacteria, and invertebrates. As the material is broken down by those decomposers, it releases nutrients that are beneficial to your plants and soil. "Compost helps introduce a thriving ecosystem into your soil that continues to interact with the organic material around it, as well as other soil-based organisms and plant root systems," says Java Bradley of Java's Compost.

Reduces Soil Erosion

Additionally, the organic matter helps with water retention, meaning it protects against the effects of drought. At the same time, compost acts as a sponge, enabling it to absorb almost five times its weight in water. "This helps lessen the impact of storm water, like soil erosion," says Bradley. What's more, compost can function as a filter by immobilizing and degrading pollutants, which improves water quality in local watersheds.

Helps Prevent Plant Disease

By improving soil quality, compost also yields healthier plants that have more resistance to certain diseases. "This also reduces the need for chemicals in our farms, gardens, landscaping, and lawns," says Bradley.

Lessens Waste

Food scraps and materials that would have otherwise gone into your garbage are now used to make compost, thus cutting your trash volume. "This means fewer plastic bags wasted and fewer trips to the dump," says Bradley. Not to mention easing up on landfill space.

Ingredients for Composting

Successful composting depends on the right combination of green (nitrogen-rich) material and brown (carbon-rich) material. The most common ratio is 4 parts browns to 1 part greens.

• Browns: This is carbon-rich material, like leaf litter, shredded paper or cardboard, sawdust, or yard debris.
• Greens: This is nitrogen-rich material, like food scraps, fresh coffee grounds, or fresh cut grass.
• Air: Aerobic microorganisms need oxygen to survive. The microorganisms are essential, as they are what turns food and garden waste into compost.
• Moisture: The compost pile should be consistently moist. While rainfall and moisture from food scraps are generally sufficient, supplemental water from a garden hose can help during dry, hot conditions.
  

What to Compost

Most of the things commonly added to compost piles can be found inside and outside your home.

• Fruit and vegetable scraps
• Dry leaves
• Grass clippings
• Plant stalks and twigs
• Coffee grounds and paper filters
• Shredded brown bags
• Shredded cardboard
• Eggshells
• Untreated wood chips

What Not to Compost

Even if they can decompose, there are some things you shouldn't add to your compost pile.

• Meat, fish, and bones
• Cheese and dairy products
• Fats, oils, and grease
• Herbicide-treated plants
• Aggressive weeds
• Diseased plants
• Treated or painted wood

Types of Composting

There are a few different ways you can make compost.

Hot Composting

Hot composting, the most common method, needs the correct ratio between the nitrogen-rich and carbon-rich material in order to heat up and decompose. This process is quicker, but requires close attention as too much carbon-rich material can cause the temperature of the compost pile to dip too low.

Cold Composting

Unlike hot compost, little or no heat reaction occurs as the material decomposes when making cold compost. To do this, the materials are added to the pile, mixed occasionally, and kept moist. While this method is low-maintenance because you don't need to worry about the ratio of greens to browns, the compost isn't ready until the following year.

Vermicomposting

Vermicomposting relies on earthworms to help stabilize active organic materials and convert them into compost. Earthworms will consume most organic materials, including food waste, scrap paper, and yard trimmings.

Types of Compost Bins

There are many compost bins to choose from, but some are more common than others. Alternatively, you can DIY your own compost bin in a few easy steps.

Open Bottom Bin

Some compost bins sit directly on the ground and have an opening at the bottom. "This allows for the microbiology already present in the soil to find its way into the compost pile and accelerate the process," says Bradley. These bins are great because they never seem to get full as the microorganisms break down the compost. One downside is that they're not as effective at keeping pests from feeding or nesting in your pile.

Tumblers

Tumblers are closed cylinders that are usually raised off the ground. "Closed systems are easy to manage. You just add your browns and greens and turn your compost," says Bradley. Although tumblers are more expensive than some other systems, they're very good at keeping most animals out—some models are made out of galvanized steel and are lockable.

DIY Compost Bin

There are a few ways to make a DIY compost bin, but the easiest technique is to attach five wooden pallets together to make a cube with the top open. "You can throw in food waste and yard waste, and let the pile decompose until it is ready to apply to the garden," says Dan Kemper, expert trainer at the Rodale Institute.

How to Make Compost

When making hot compost, find a location that offers part sun or part shade. Full sun may require more frequent watering, while full shade slows decomposition.

1. Collect your green and brown materials and deposit them into your bin.
2. Water as needed—the pile should be moist but not dripping.
3. Monitor the pile for temperature ranges. You compost pile should reach 140 degrees Fahrenheit to ensure the microbes are breaking down the materials appropriately.
4. Periodically stir your compost with a pitch fork or a shovel to ensure even composting and provide oxygen for the microorganisms.

You may need to adjust your ratio of greens and browns as your pile breaks down into compost. "If the temperature begins to fall below thresholds, add more fresh greens and turn the compost to add oxygen back to the pile," says Erik Stefferud, soils and compost manager at Longwood Gardens. On the other hand, if you start to notice the pile is too wet or smells bad, you should increase your browns.  

Signs Your Compost Is Ready

From start to finish, it usually takes a few months to make a batch of compost. "Once there are no visible food scraps or green garden waste and your compost pile is no longer heating up after mixing, it’s time for it to cure for at least four weeks," says Stefferud. "After curing, expect your pile to shrink to about one-third of its original size." You should be left with finished compost that looks dark, feels loose, and smells like fresh soil. Most, if not all, of the organic matter should be decomposed.