What Not to Put in Compost – Common Mistakes to Avoid

Compost is great for turning waste into soil, but not everything belongs in the bin. Adding the wrong stuff can slow down the process, create odors, or even attract pests. Below you’ll find the top things to keep out of your compost and simple ways to fix common problems.

Items That Harm Your Compost

Meat, fish, and bones – These break down slowly and smell bad. They also draw rats and flies. If you want to recycle protein, stick to plant‑based scraps or use a separate worm bin.

Dairy products – Milk, cheese, yogurt and butter create a greasy environment that stops good microbes from working. They also cause foul smells.

Oily foods – Cooking oil, buttered toast, and greasy leftovers coat the compost material, making it water‑repellent. This slows decomposition and can create a slick surface.

Pet waste – Dog or cat poop can contain parasites and harmful bacteria. It’s safer to dispose of pet waste in the trash or use a dedicated pet compost system.

Diseased plants and weeds with seed – If the plant is sick, the disease can survive the composting process and spread to your garden. Weeds that have gone to seed will re‑sprout when you use the compost.

Glossy or dyed paper – Magazines, receipts, and shiny packaging often have inks or coatings that don’t break down well. Stick to cardboard, newspaper, and plain paper.

Charcoal and ash – Small amounts of wood ash can be okay, but charcoal seeds the pile with chemicals that affect pH and microbes.

Large branches and woody material – These take ages to decompose. Cut them into small pieces or add them to a separate pile for slow breakdown.

How to Keep Your Compost Healthy

Balance is key. Mix green (nitrogen‑rich) items like kitchen veg scraps with brown (carbon‑rich) stuff such as dry leaves, straw, or shredded paper. Aim for roughly a 1:3 green‑to‑brown ratio.

Turn the pile every week or two. This adds oxygen, speeds up microbes, and prevents a smelly, soggy mess.

Keep the pile moist, like a damp sponge. If it’s too dry, add water; if it’s too wet, add more brown material.

Cover the top with a layer of leaves, straw, or a tarp. This stops rain from making it soggy and keeps flies away.

Watch the temperature. A hot pile (130‑150°F) kills most weed seeds and disease. If it’s not heating up, add more greens or turn it.

Finally, remember that patience pays off. Good compost can take a few months to a year, depending on what you put in. By staying clear of the no‑go items listed above, you’ll get dark, crumbly soil that boosts plant growth.

Got more questions about composting? Feel free to explore our other guides on sustainable gardening, drip irrigation, and indoor plant care. Happy composting!