Composting 101: What You Can and Can't Compost

 Composting 101: What You Can and Can't Compost

If you ever wondered how to convert your kitchen scraps and yard trimmings into fertile soil, you should compost. Composting is a very sustainable practice for processing organic waste and lowering your carbon profile. Not only does it minimize landfill waste, but it also makes garden soil better, limits your use of chemical fertilizers, and makes for a more circular lifestyle.

However, composting is not as easy as putting everything organic in a heap. There is an art and science to what can and cannot be composted. In this easy-to-follow guide for beginners, we will demystify the composting fundamentals and teach you the do's and don'ts of home composting.

What Is Composting?

Composting is nature's way of recycling organic waste—such as leaves, vegetable peels, and coffee grounds—into a nutrient-dense soil amendment known as compost. Microbes, fungi, worms, and insects accomplish this task by decomposing the items over time. The end result is "Black gold" that improves soil structure, stimulates plant growth, and holds water.

The Essentials of a Healthy Compost Pile

Any successful compost pile needs four essential ingredients:

Greens – These are nitrogen-rich waste materials such as fruit and veggie peels, coffee grounds, and fresh grass clippings.

Browns – These contribute carbon and contain things such as dried leaves, straw, cardboard, and paper.

Water – Water assists in breaking down the material.

Air – Oxygen is essential for aerobic microbes that break down the waste.

A well-balanced compost pile would have a good mix of greens and browns (a ratio of 1 part green to 3 parts brown). Excessive greens make the pile stinky, while excessive browns retard decomposition.

What You Can Compost

We begin with what you can compost safely in your compost pile or bin. These are typically organic, biodegradable, and home-safe for composting.

Kitchen Scraps (Greens):

Fruit and vegetable peels, cores, and scraps

Coffee grounds and filters

Tea bags (ensure they're plastic-free)

Eggshells (crushed for faster breakdown)

Cooked rice or pasta (in small amounts)

Expired plant-based food (non-oily or seasoned)

Yard Waste (Browns and Greens):

Grass clippings (in thin layers to prevent matting)

Leaves (shredded if possible)

Plant trimmings

Sawdust and wood shavings (from untreated wood)

Twigs and small branches (chopped up)

Paper and Cardboard (Browns):

Newspaper (black-and-white print only)

Cardboard (shredded and non-glossy)

Paper towels and napkins (if not greasy or soiled with chemicals)

Paper egg cartons

Toilet paper tubes

Other Compostables:

Pet hair and human hair

Feathers

Natural fibers such as cotton or wool shreds

Fireplace ash (in small quantities and only from untreated wood)

What You Can't Compost

Not all organic material is compost-ready. Some materials can attract pests, cause odor issues, or contaminate your compost pile with toxins.

Animal Products:

Meat, poultry, and fish trimmings

Bones

Dairy products (cheese, milk, yogurt)

Grease, fat, and oils

These can produce unpleasant odors and bring in pests such as raccoons, rodents, and flies. Industrial composting is perhaps capable of dealing with these, but they are not acceptable in home composting.

Human and Pet Waste:

Dog feces or cat litter

Diapers or sanitary items

Human feces

These can harbor pathogens that are hazardous in a home compost system.

Treated or Toxic Materials:

Shiny or coated paper (magazines, printed cardboard)

Chemically treated or painted wood

Chemically dyed clothing

Charcoal or coal ash

These materials can leach toxic chemicals into your compost, which can damage soil organisms and plants.

Invasive Weeds and Plants:

Weeds with seed

Invasive plants (such as morning glory or bindweed)

These will pass through the composting process and come back into your garden when you plant with the compost.

Other No-No's:

Plastic, metal, or glass

Synthetic clothing

Contents of vacuum cleaner (can have synthetic trash)

Sticky labels on fruits and vegetables

Cigarette filters

Tips for Successful Composting

Even when composting proper materials, a neglected pile can still fail. Here are some tips to ensure your compost pile remains healthy:

1. Chop Large Items

Shred big chunks or woody pieces. Smaller ones break down quickly and create more balanced compost.

2. Turn Regularly

Aerate the compost by turning it every 1–2 weeks. This provides oxygen, accelerates decomposition, and suppresses odor buildup.

3. Monitor Moisture

Your compost should be as wet as a wrung-out sponge. If it's too dry, add water or wet green scraps. If it's too wet, add dry browns such as shredded paper or leaves.

4. Balance Greens and Browns

Too many greens result in a stinky, slimy mess. Too many browns slow down decomposition. Fix the balance if things don't seem right.

5. Be Patient

Composting is a slow process—anywhere from 2 to 6 months for mature compost, depending on your system and materials.

Popular Composting Techniques

Based on your lifestyle and space, you may experiment with various composting techniques:

Backyard Bin or Pile: Best for homeowners with space outdoors. Utilize a separate compost bin or pile in a shaded location.

Tumbler Composter: Enclosed composter system that simplifies turning. Excellent for faster breakdown.

Vermicomposting: Utilizes worms (red wigglers) to compost food waste in homes or small environments.

Bokashi: A Japanese technique utilizing fermentation to pre-treat food waste, such as meat and dairy. Needs a closed container and special bran.

Final Thoughts

Composting is about as easy as it gets and one of the most effective things you can do for the planet. Knowing what you can compost and what you can't will save you from costly mistakes and keep your compost healthy and useful. Whether you're gardening vegetables, flowers, or just want to eliminate household waste, composting takes commonplace scraps and makes them something worth its weight in gold—rich, living earth that pays dividends to the planet.

So the next time you're getting ready to throw away those coffee grounds or carrot peels, think of giving them a second chance in the compost bin. Your garden—and the earth—will thank you.