What You Can And Can’T Compost – The Definitive List For Rich, Healthy
Ever stand over your kitchen bin, holding a banana peel or a leftover piece of bread, and wonder, “Can I compost this?” You’re not alone. It’s one of the most common questions we get here at Greeny Gardener, and the uncertainty can feel a little overwhelming.
But I promise you this: mastering your compost pile is one of the most rewarding things you can do for your garden. It’s simpler than you think, and the payoff is immense. We’re talking about creating rich, nutrient-dense “black gold” that will make your plants thrive—all while reducing your household waste.
In this complete what you can and can’t compost guide, we’re going to break it all down. We’ll cover the absolute must-haves for your pile, the definite no-gos, and some surprising items you probably didn’t know you could compost. Let’s turn your compost confusion into confidence!
What's On the Page
- 1 The Magic Behind Composting: Understanding “Greens” and “Browns”
- 2 Your Ultimate “YES” List: What You CAN Compost
- 3 The Definitive “NO” List: What You CAN’T Compost (And Why!)
- 4 Common Problems with What You Can and Can’t Compost (And How to Fix Them)
- 5 What You Can and Can’t Compost Best Practices for Success
- 6 Frequently Asked Questions About What You Can and Can’t Compost
- 7 Your Journey to “Black Gold” Starts Now
The Magic Behind Composting: Understanding “Greens” and “Browns”
Before we dive into the lists, let’s talk about the simple science that makes composting work. A healthy, happy compost pile needs a balanced diet of two things: nitrogen-rich “Greens” and carbon-rich “Browns.”
Think of it like building a lasagna. You layer these materials to create the perfect environment for beneficial microorganisms to break everything down into beautiful, crumbly soil conditioner. This is the foundation of eco-friendly what you can and can’t compost practices.
The “Greens” (Nitrogen-Rich Ingredients)
These are the “wet” materials that provide nitrogen, a crucial protein-builder for the tiny organisms doing all the hard work in your pile. They tend to heat up the pile and speed up decomposition.
- Fruit and Vegetable Scraps: Apple cores, banana peels, carrot tops, lettuce—you name it.
- Coffee Grounds and Tea Bags: Yes, even the paper filter and tea bag! Just remove any staples.
- Fresh Grass Clippings: A fantastic source of nitrogen, but add them in thin layers to avoid a slimy mess.
- Plant Trimmings: Freshly cut flowers and green leaves from your garden.
- Eggshells: A great source of calcium. It helps to crush them first to speed up breakdown.
The “Browns” (Carbon-Rich Ingredients)
These are the “dry” materials that provide carbon, which is the energy source for the microbes. They also provide bulk and allow air to circulate, preventing your pile from becoming a stinky, sludgy mess.
- Dried Leaves: The absolute king of browns. Stockpile them in the fall!
- Twigs and Small Branches: Break them into smaller pieces to help them decompose faster.
- Shredded Cardboard and Newspaper: Uncoated, non-glossy paper products are perfect. Avoid colored inks if you can, though most modern soy-based inks are fine.
- Sawdust and Wood Chips: Only from untreated wood.
- Pine Needles: They are acidic, so use them in moderation.
- Dryer Lint: From natural fibers like cotton or wool.
The Ideal Ratio for a Happy Pile
The golden rule for a fast, odor-free compost pile is to aim for a ratio of roughly 2 to 3 parts “Browns” to 1 part “Greens” by volume. Don’t stress about getting this perfect! It’s more of a guideline. If your pile gets smelly, add more browns. If it’s too dry and inactive, add more greens and a splash of water.
Your Ultimate “YES” List: What You CAN Compost
Ready to get started? Here is your go-to checklist for compost-friendly materials. This is the core of how to what you can and can’t compost correctly.
From the Kitchen
- All fruit and vegetable scraps (peels, cores, skins)
- Eggshells (crushed)
- Coffee grounds and paper filters
- Tea leaves and paper tea bags (staple-free)
- Stale bread, crackers, and cereal (in moderation)
- Cooked pasta and rice (in moderation, buried deep in the pile)
- Corn cobs and husks
- Nutshells (except for walnut shells, which can inhibit plant growth)
From the Garden & Yard
- Grass clippings (in thin layers)
- Leaves
- Weeds (that haven’t gone to seed)
- Dead plants and flowers (as long as they aren’t diseased)
- Small twigs and wood chips
- Straw and hay
- Old potting soil
Around the House (The Surprising Stuff!)
- Shredded newspaper (not the glossy ads)
- Shredded cardboard (toilet paper rolls, paper towel tubes, egg cartons)
- Dryer lint from natural fibers (cotton, linen, wool)
- Hair and pet fur
- 100% cotton balls and swabs with cardboard sticks
- Old wine and beer (it can help activate the pile!)
The Definitive “NO” List: What You CAN’T Compost (And Why!)
Just as important as knowing what to add is knowing what to leave out. Avoiding these items is key to preventing pests, bad smells, and other common problems with what you can and can’t compost.
Meat, Fish, Bones, and Dairy Products
Why: These are an open invitation for pests like raccoons, rats, and flies. As they rot, they also produce a truly foul odor that will make you (and your neighbors) very unhappy.
Includes: Cheese, milk, yogurt, butter, meat scraps, bones, fish skins.
Oily, Greasy, or Fatty Foods
Why: Oils and fats throw off the moisture balance of your pile and can coat other materials, slowing down decomposition to a crawl. They are also another major attractant for pests.
Includes: Cooking oil, salad dressings, mayonnaise, fatty leftovers.
Diseased or Pest-Infested Plants
Why: Most backyard compost piles don’t get hot enough to kill off pathogens like fungal spores or insect eggs. Adding diseased plants is a surefire way to reintroduce those same problems back into your garden next season.
Pro Tip: When in doubt, throw it out (in the trash, not the compost!).
Pet Waste (and a Note on Manure)
Why: Waste from dogs and cats can contain harmful parasites and pathogens (like E. coli or roundworms) that are dangerous to human health. Never add it to a compost pile you intend to use on edible plants.
The Exception: Manure from herbivores like chickens, rabbits, cows, and horses is a fantastic compost activator, but it should be well-composted before being applied to the garden.
Treated Wood, Coal Ash, and Chemicals
Why: This one is all about safety. Treated or painted wood contains chemicals like arsenic that can leach into your finished compost. Coal and charcoal ash contain sulfur and iron in amounts that can damage plants.
Includes: Pressure-treated lumber, sawdust from treated wood, charcoal briquette ash, glossy magazines with heavy chemical inks.
Common Problems with What You Can and Can’t Compost (And How to Fix Them)
Don’t worry if your compost pile isn’t perfect right away! Every gardener runs into a few hiccups. Here are some quick fixes based on decades of experience.
“My Compost Pile Smells Awful!”
A foul, ammonia-like smell usually means you have too many “greens” (nitrogen) and not enough air. It’s become waterlogged and anaerobic.
The Fix: Turn the pile thoroughly with a garden fork to aerate it. As you turn, mix in a generous amount of “browns” like shredded leaves or cardboard to soak up excess moisture and balance the carbon-to-nitrogen ratio.
“My Compost Isn’t Breaking Down.”
If your pile looks the same week after week, it’s likely too dry or has too many “browns.” The microbes have run out of food or water.
The Fix: Use a hose to lightly moisten the pile until it feels like a wrung-out sponge. Mix in some fresh “greens” like kitchen scraps or grass clippings to give the microbes a nitrogen boost. Then, give it a good turn!
“I Have Pests and Critters!”
Finding unwanted visitors in your pile is often a sign you’ve added something from the “NO” list, or that food scraps are too exposed.
The Fix: First, stop adding meat, dairy, or oily foods. Second, always bury your kitchen scraps in the center of the pile and cover them with a layer of browns. If pests persist, consider a fully enclosed compost tumbler or bin.
What You Can and Can’t Compost Best Practices for Success
Ready to create the best compost on the block? Follow these simple tips from our what you can and can’t compost care guide to elevate your game.
Size Matters: Chop It Up!
The smaller the pieces you add, the more surface area the microbes have to work on. This dramatically speeds up decomposition. Chop up large vegetable scraps, shred cardboard, and run over leaves with a lawnmower before adding them to the pile.
The Importance of Moisture
Your compost pile should be consistently moist, but not soaking wet. The ideal texture is that of a damp sponge. If it gets too dry, especially in hot weather, give it a light watering. If it’s too wet from rain, mix in more dry browns.
Turning and Aeration
Oxygen is vital for the aerobic microbes that do the best composting work. Turning your pile with a garden fork or pitchfork every week or two mixes everything together, prevents compaction, and introduces fresh air. This is the single best thing you can do to speed up the process.
Frequently Asked Questions About What You Can and Can’t Compost
Can I compost citrus peels and onions?
Yes, absolutely! There’s a common myth that they will harm worms or make the compost too acidic. In a balanced, active pile, they break down just fine. The natural chemicals they contain are not potent enough to cause any issues in a typical backyard compost system.
What about bread, pasta, and cooked grains?
You can, but with caution. These items are fine in small amounts, but they can become a dense, gluey mass that impedes airflow. They are also a favorite food for rodents. If you add them, break them into small pieces and bury them deep within the center of a hot pile.
How do I know when my compost is ready to use?
Finished compost is a beautiful thing! It will be dark, rich, and crumbly, with a pleasant, earthy smell like a forest floor. You should no longer be able to identify the original materials you put in. This can take anywhere from a few months to a year, depending on your methods.
Your Journey to “Black Gold” Starts Now
See? The world of sustainable what you can and can’t compost isn’t so complicated after all. It’s a simple dance of balancing your greens and browns, knowing what to leave out, and giving your pile a little attention now and then.
By turning your scraps into soil, you’re not just feeding your garden—you’re participating in a beautiful, natural cycle. You’re reducing landfill waste, improving your soil structure, and growing healthier, more vibrant plants.
So grab that bucket of kitchen scraps, head out to your pile with confidence, and start creating that amazing “black gold.” Your garden will thank you for it. Happy composting!
