Learn How to Make Compost from Kitchen Scraps and Yard Waste!
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Don’t throw out your garden debris or kitchen vegetable scraps! Turn them into rich, crumbly, organic material to help plants thrive We’ll show you two different composting methods—”cold” and “hot.” Cold is easier, but hot transforms scraps into compost more quickly.
What Is Compost?
Compost is a nutrient-rich, soil-like material made up of decomposing organic matter—most often fallen leaves, grass clippings, plant debris, vegetable scraps, and yard waste. The key idea behind composting is that the materials and waste that you might normally throw away can be recycled to help plants grow, delivering better harvests and flower blooms.
Also, compost fixes soil problems. If the key to a successful garden is good soil (and it is), compost is the gardener’s secret weapon. It has been lovingly called the “gardener’s great equalizer” because of its ability to amend soil. Is your soil too sandy? Compost will hold sand particles together so they can absorb water like a sponge. Troubled by hard clay soil? Compost attaches to particles of clay, creating spaces for water and nutrients to flow to plant roots. Even in perfectly loamy soil, compost brings something: a ton of nutrients.
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Where to Compost
In community gardens, you may see a series of several bins filled with organic matter in different states of decomposition, but don’t let a professional system like that intimidate you! It’s a common misconception that you need to have a large outdoor space in order to practice composting. You can make your own compost in a space as small as a patio or balcony.
Are Compost Bins Necessary?
At its most basic, a composting system doesn’t need to consist of anything more than a pile in the corner of your yard. As long as the pile ends up being about 4 feet high, 4 feet wide, and 4 feet deep, it should successfully decompose everything you throw at it.
Most compost piles, however, have a dedicated structure that keeps it all contained—something like a cube made of wood pallets or even a purpose-built plastic compost bin. Here’s how to make your own compost bin! Fancy bins with multiple layers and sifters are nice but not necessary.
It’s also possible to compost right in your garden bed. Learn more about composting “in situ.”
What Can Be Composted?
Most organic materials can be composted. As mentioned above, this includes things like fallen leaves, grass clippings, shredded newspaper, wood chips, vegetable scraps, and so on.
In addition to the ingredients mentioned above, any of these items may be added to a compost pile:
- Coffee grounds and loose tea or compostable tea bags (note that most tea bags are not fully compostable, so tear or shred them before adding to compost)
- Dry goods (crackers, flour, spices)
- Eggshells
- Hair
- Nutshells
- Pasta (cooked or uncooked)
- Seaweed
- Shredded paper/newspaper
- Cardboard (non-glossy)
- Bedding from chicken coops or from small mammal pets (guinea pigs, rabbits, hamsters, etc.)
What CAN’T Be Composted?
Materials that you should NOT put in your compost pile include inorganic materials (rock, glass, metal, plastic, etc.) and animal products, like bones, seafood, meat scraps, dairy products, and grease. (Eggshells are an exception since they break down easily and are a good source of calcium!) Additionally, don’t add dog or cat waste (nor kitty litter) to your compost pile, as these may contain parasites or other nasty things that may not get completely decomposed.
Also, if you’re collecting grass clippings from the neighbors, make sure they don’t use weed killers on their lawns. Those chemicals take forever to break down and will negatively impact any plants on which you use your finished compost.
4 Essential Ingredients of a Healthy Compost Pile
A productive compost pile needs four things:
- Brown matter (“browns”): This is carbon-rich material such as straw, wood chips, shredded brown cardboard, or fallen leaves.
- Green matter (“greens”): These are nitrogen-rich materials like grass clippings, weeds, manure, or kitchen scraps. Greens should have a carbon-to-nitrogen ratio of about 30:1.
- Water: The pile should be kept consistently moist, which is especially important if you add lots of dry leaves or hay. Usually, rainfall is enough to keep it damp, but in a dry summer, you might have to spray it with water.
- Air: Oxygen is necessary for aerobic microorganisms to survive. They are the ones doing all the work of turning your garden waste into black gold.
Keep in mind that color isn’t always a reliable indicator of what is green or brown. For example, fresh grass clippings—even when spread out and left to dry—are still considered a “green” ingredient even though they’ve turned a brownish color (because really all they’ve lost is water). On the other hand, straw is always considered “brown” because, before the main stems died, much of the plant’s nitrogen had gone into the seeds as protein before the plant was harvested.
Compost decomposes much faster if you chop up the ingredients, so shredding woody materials and tearing up cardboard speeds up the process because there is more surface area exposed to the microbes that decompose the organic matter.
Air is vital to the composting process, so it’s important to mix the ingredients together and never squash them down. Many people turn their compost piles several times over the summer. Turning your compost helps speed up the process of decomposition, but it is not necessary as long as the pile isn’t completely compacted. It will all rot eventually!
Composting Methods: Hot vs. Cold Composting
1. Hot (or “Active”) Composting
The most effective way to produce rich garden compost is to create a hot, or active, compost pile. It’s called “hot” because it can reach an internal temperature of up to 160°F (71°C) and “active” because it destroys—essentially by cooking—weed seeds and disease-causing organisms. A temperature of about 140°F (60°C) is what you should aim for in a hot, active compost pile. (The size of the pile, the ingredients, and their arrangements in layers are key to reaching that desired outcome.)
Use the Right Ratio
When making a hot compost pile, you want to have 2 to 3 times more brown materials than greens, at least initially, although some more greens can be added as the compost cooks.
For most gardeners, the biggest challenge is, therefore, collecting enough brown materials and not just piling in loads of greens, which will result in a soggy, smelly mess. For example, never add lots of grass clippings in one go, as they will just form a slimy, matted layer.
On the other hand, avoid adding too much brown matter at once, too. Dumping your fall leaves into the compost heap all at once can really slow things down! Add them in modest qualities along with fresh green ingredients. Or, compost them separately over one or two years as leaf mold. See how to make leaf mold here.
Alternate layers of brown and green matter when building your hot compost pile, and add a few shovels full of garden soil to contribute to those essential soil microbes. The more green matter, the hotter the pile will get, and the faster it will decompose. Heat also helps to kill off disease spores and weed seeds.
How Big Should the Compost Pile Be?
A hot compost pile should be at least 3 feet in diameter, though slightly larger (4 feet) is ideal. The pile will shrink as the ingredients decompose. Consider keeping the contents in place with chicken netting; wooden sides would be even better to keep the pile contained.
Making a Hot Compost Pile
Cutting up or shredding materials helps speed up the process.
- Pile the ingredients like a layer cake, with carbon-rich materials (browns) on the bottom. Placing twigs and woody stems here will help air circulate into the pile.
- Next, cover the layer with soil.
- Add nitrogen-rich materials (greens), followed by soil. Repeat the alternating layers of greens and browns until the pile reaches 2 to 3 feet high.
- Soak the pile at its start and water periodically; its consistency should be that of a damp (not wet) sponge.
Punch holes in the sides of the pile or push 1—to 2-foot lengths of hollow pipe into them to add air to the interior.
Your compost pile should start cooking within a week or so. Check the temperature of the pile with a compost thermometer or an old kitchen thermometer. A temperature of 110°F to 140°F (43°C to 60°C) is desirable. If you have no heat or insufficient heat, add nitrogen in the form of soft green ingredients or organic fertilizer.
Once a week, or as soon as the center starts to cool down, turn the pile. Move materials from the center of the pile to the outside. (For usable compost in 1 to 3 months, turn it every other week; for finished compost within a month, turn it every couple of days.)
See our new video on making super-fast compost!
2. Cold (or “Passive”) Composting
Cold, or passive, composting requires less effort than hot composting. You essentially let a pile of organic matter build and decompose, using the same types of ingredients as you would in a hot compost pile. The difference is that you don’t spend time turning the pile or carefully managing the ratio of greens to browns.
Cold composting requires less effort from the gardener, but the decomposition takes substantially longer—a year or more!
Making a Cold Compost Pile
To cold compost, simply create a pile of organic materials that you add to as you find or accumulate them. If possible, alternate layers of browns and greens, mixing in a few shovelfuls of garden soil, too. Since they’ll take longer to break down, bury kitchen scraps in the pile’s center to deter curious insect and animal pests.
NOTE: Avoid adding weeds or diseased plant materials to a cold compost pile, as the pile will not reach the high temperatures capable of killing weed seeds and diseases. (In fact, weeds may germinate in a cold pile.)
3. Vermicomposting (Composting with Worms)
Yet another composting method is something called “vermicomposting,” which employs worms to do the hard work of breaking down your organic waste and scraps. Vermicomposting is probably the most space-saving composting method since it can be done in something as small as a 10-gallon plastic tub. Getting a vermicomposting system started is the hardest part since you’ll need to buy materials and get yourself a sufficient number of worms to begin with (and not all worms are suitable!), but after that, all it takes to maintain a vermicomposting system is feeding it regularly with kitchen scraps.
If you don’t have a lot of space and mainly want to compost kitchen scraps, vermicomposting could be the composting method for you. Learn more about vermicomposting here!
Composting Problems and Solutions
Composting doesn’t have to be messy, stinky, or complicated, but sometimes problems do arise. Usually, it’s easy to get your compost pile back on track.
What Should I Do If My Compost Is Too Wet?
Too much green matter can result in slimy, wet compost piles. Avoid soggy piles by alternating wetter ingredients (such as fresh grass clippings) with drier and more fibrous ingredients (such as dry leaves, cardboard, and woodier crop residue). The resulting mix should be damp but not sodden. You can also sprinkle wood ash onto your heap but, importantly, it must be wood ash and not coal ash.
Why Does My Compost Smell Bad?
If a foul odor emanates from your compost bin or pile, flip the compost to introduce more air. Mixing the compost not only gives it plenty of air but results in a finer end product that is easier to spread. A good compost heap has a slightly sweet compost-y smell. If it smells sour or rotten, it either has too many greens or is too wet.
How Do I Keep Pests Away From My Compost Pile?
Avoid cooked food waste and animal products like meat and dairy, which attract rats and other pests. Try burying veggie scraps or other food waste in the center of your pile so that it’s not as accessible to pests. If rodents are a problem, ease off adding potato peelings, which are a favorite snack.
Can I Compost Weeds?
Composting weeds is fine as long as the weeds haven’t yet set seed. A hot compost pile should be able to cook the seeds to make them inert, but it’s still a risk. In any case, avoid invasive perennial weeds such as bindweed and black swallow-wort—these are better off disposed of in the trash!
See the video on how to fix composting problems.
Take the plunge and get composting! You’ll feel great doing it. Or, if you’re already composting, share your tips for supercharging your compost!
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Catherine Boeckmann
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I've never had a compost pile in my small yard, but last year discovered blender composting for kitchen scraps. It's so easy - put the scraps (egg shells, tea bags, veggies and fruits) in a blender with water, blend, and pour around the plants. Eventually they will break down and in the meantime no critters can eat them.
I had pretty good success with a large plastic tumbler for two years; I learned to cover it when it rained substantially, or the mix would get too wet and rot. I keep shredded plain brown wrapping paper in a container to add if the mix becomes too wet (neither my prodigious magnolia or umbrella tree leaves break down enough to use in the compost).
However, for the last two summers I wind up with an invasion of light brownish maggots about a half-inch long that completely take over, and render the compost very odorous, disgusting and wet, as well as reducing the whole thing in volume into a small wet mess. I just let it dry out, and put it out for the birds to peck at when it's manageable.
Any hints at preventing these maggots? No idea where they come from. I used to use dried fig leaves, but stopped in case that was the problem.
Thanks for any ideas.
Hi, Tony,
Maggots can sometimes appear in compost piles and actually can be beneficial in certain cases (and certain species are sometimes added to piles), as they break down organic material quickly. However, when they become numerous, it can be alarming. Often large populations can indicate that the pile is too wet or has too much kitchen waste.
There are several species of flies whose larvae may live in compost. A few of the more common is the black soldier fly (whose gray-white to dark brown, segmented larvae are about an inch long) and the common housefly (whose creamy white larvae are about 1/2 inch long). Houseflies are attracted to meat and dairy, and manure. Avoid adding fats or too much manure or grass clippings to the pile. Turn the pile frequently. When you add any food scraps to the pile, be sure to turn the pile immediately, as those materials should be buried in the pile, not on the surface. It sounds like you have been doing the right thing in mixing in more browns (shredded brown paper) to the pile when it becomes too wet, but perhaps try adding a little more to see if that might help. If there are air holes in the tumbler, cover the openings with fine mesh, so that the adult flies can not lay their eggs inside. Flies are attracted to warmer temperatures—is your compost tumbler in full sun? If you have a compost bucket for food scraps before they are added to the pile, keep it in a cool, dry place and add some browns to make the environment less inviting for flies.
Hope this helps!
I have recently read that you should not put acidic matter such as tomato or citrus products into your compost.
Is this correct?
Where do you suggest to get worms from for vermicomposting?
I am what is called a lazy composter. We have 2 plastic compost bins from a local county class we took. I just pile it in, more or less in the correct ratio, and let it go. Once in a while I'll add water, turn it or if it smells ( my wife doesn't cut food waste into small pieces ) I will turn it and cover it with shredded paper or soil. It still comes out OK and I can harvest a small batch every couple of months.
We also have a compost tumbler, not happy with it, never have been able to get the mixture quite right. But I use it sometimes for prepping materials for the bins, especially when harvesting is over and we have all the plant materials.
Can one add compost on top of the soil (once the vegetable plants have been removed) in a 5-gallon container and close the container for the winter?
Hi Thomas, You can certainly add finished compost to the top of the soil in your 5-gallon container. We would not recommend adding composting material to your bucket, e.g. food scraps, because it would not have time to break down over the winter. The material you want to add is the end result of the composting process. Depending on your location, cracking of your container could be a concern in low temperatures, so don’t leave it exposed to the elements. Whatever you plan to plant in your container next spring will benefit from the addition of compost to the soil this fall.
Thank you. Here in Québec City, I am leaving the containers without water for a couple of months to prevent splitting. The compost I will be adding is from a tumbler that I started composting last fall, so it should be finished composting.
HELP! How can I use all the cardboard from boxes from Amazon and others?
