What Not to Compost: 8 Essential Rules for Healthy Backyard Compost

Knowing what not to compost is key for healthy backyard compost. Avoid adding meat, fish, bones, or dairy because they attract pests and create bad smells. Instead, stick to plant-based scraps and yard waste that break down safely and quickly.

Keep citrus, eggshells, and bread out of your pile or add them sparingly. These can slow decomposition or cause imbalances in your compost. Also, skip pet and human waste to avoid risks of harmful bacteria.

Stay away from plastic, glossy paper, and synthetic materials since they won’t break down. Use natural, biodegradable items in your compost pile.

Keep the pile’s temperature above 130°F. This heat kills weed seeds and harmful pathogens. This helps ensure your compost is safe and ready for your garden in a few months.

1. Which Materials Should You Never Compost?

Some materials should never go in your compost bin because they cause problems. Meat, dairy, fats, and oils break down slowly and often produce strong, unpleasant smells.

These smells draw pests like rats, flies, and raccoons. They can bring a bigger mess to your yard.

Plastic, coated papers, and glossy materials don’t decompose well at home. They often have plastic or wax layers that resist breaking down. Over time, these materials just add trash to your compost instead of healthy soil nutrients.

Adding these items can disrupt your compost’s balance and slow the entire process. Meat and dairy often contain bacteria that can survive in slow home compost piles. This risk invites pests and can create unsafe compost for your garden.

Plastic-coated papers, like produce stickers or shiny flyers, don’t rot. They usually end up as small plastic bits in your compost pile, causing contamination. Choose uncoated cardboard or newspaper scraps instead, which break down quickly and add carbon.

2. Why Avoid Meat, Fish, Bones, and Dairy in Compost?

Meat, fish, bones, and dairy break down very slowly in home compost. These animal products contain fats and oils that produce strong, bad smells as they rot. The smell can linger and ruin the pleasant earthy scent good compost has.

These odors attract pests like rats, raccoons, and flies. Pests dig into compost bins, sometimes damaging or knocking them over. Even a locked bin may not stop hungry scavengers.

They are drawn by the smell of meat or dairy. Scavengers can be very determined to get in.

Cooked animal products cause more trouble than raw ones. They often have added fats, spices, or sauces. These additions can attract pests and slow composting.

These ingredients ferment and create an even stronger stench. Cooked foods also break down unevenly, inviting bad bacteria that slow composting.

Using these items in your compost risks unwanted guests and spreads harmful bacteria. This can contaminate your garden soil or plants. It’s better to keep meat, fish, bones, and dairy out of your compost altogether.

The safest way to compost is using plant scraps only. This includes vegetable peels, coffee grounds, and eggshells. Avoid animal products to keep pests away.

Your pile should be dry and hot enough to break down organic waste quickly. You can use sturdy bins with secure lids to keep out wildlife.

Do not feed your compost animal products. Pests will attack your bin and spread germs.

3. How Do Citrus, Eggshells, and Bread Affect Compost?

Citrus peels, eggshells, and bread can be composted but need special care. Citrus peels slow decomposition if used too much.

Eggshells add calcium but break down slowly. Bread attracts pests and clumps if not managed well.

Composting Citrus Peels Safely

Citrus peels contain natural acids and oils that slow compost breakdown. Adding too many peels can lower the pile’s pH, harming microbes.

Avoid citrus if you use worms. It can kill them.

Chop peels into small pieces to help speed up decay. Add them in small amounts mixed evenly with other materials. A good rule is less than 10% of your total compost volume.

• Cut peels into 1-inch pieces or smaller
• Mix well with leaves or kitchen scraps
• Use no more than 10% of total compost volume
• Skip citrus if composting with worms
• Turn pile regularly to spread acids evenly

These steps prevent acidity buildup and allow your compost to stay balanced and healthy.

Handling Eggshells for Better Decomposition

Eggshells add calcium and other minerals to compost but break down very slowly when whole. Crushing them into small pieces increases their surface area, speeding decomposition. Rinse and dry shells first to avoid bad smells and flies.

Use clean eggshells in moderate amounts mixed into your compost. Large piles of shells will take months to break down fully.

• Rinse eggshells to remove egg residue
• Dry them before crushing
• Crush into pieces smaller than ½ inch
• Mix evenly with other compost scraps
• Use shells in moderate amounts, not in huge piles

Following these tips keeps your compost good-smelling and nutrient-rich without attracting pests.

When to Avoid Adding Bread and Baked Goods

Stale, plain bread breaks down well. It can clump. This clumping attracts rodents, flies, and pests.

Avoid adding bread if your compost pile doesn’t get hot or is exposed outdoors without protection. Small amounts mixed into the middle of the pile reduce pests.

Avoid moldy or sweetened breads. Never add baked goods with butter, cheese, or other dairy ingredients. Large amounts of bread create soggy clumps that slow decomposition.

• Use only stale, plain bread
• Mix bread deep inside the compost pile
• Limit bread to small amounts to reduce pests
• Avoid bread with butter, cheese, or sweet toppings
• Skip bread if compost stays cool or is uncovered outdoors

These steps help your compost cycle faster and keep unwanted animals away.

4. Which Yard and Garden Waste Should Be Excluded?

Yard waste treated with herbicides or pesticides should never go into your compost. Chemicals in these treatments can survive and kill helpful microbes or your garden plants. Grass clippings with weed killer often have leftover chemicals.

Those chemicals can enter your compost mix. This can affect your garden soil.

Not all weeds belong in a compost pile. Some invasive weeds can survive if your compost is too cool. Weeds that already made seeds may also live.

Warmer compost kills them better. Home compost piles usually don’t get hot enough. They often stay below 130 to 160°F. That heat is needed to kill weed seeds.

Diseased plants also need to stay out. Many garden fungi and bacteria can live through composting and reinfect your plants later. Composting diseased plant parts risks spreading infections instead of cleaning them up.

• Grass or plants treated with herbicides or pesticides
• Invasive weeds that have gone to seed
• Diseased plant material showing fungus or bacterial signs
• Treated wood pieces or chemically coated plant debris
• Any yard waste from infected garden plants
• Seed heads from aggressive weed species

To compost safely, only add untreated and healthy yard scraps. Collect weeds separately using something like a collapsible 30-gallon garden waste bucket. Dispose of diseased plants with regular trash to avoid risks.

Keep your pile hot, turning it often to reach 130, 160°F for several days. This heat helps kill stubborn seeds and pathogens.

Avoid adding troublesome weeds if your compost stays cool. Also don’t add plants with diseases. It can spread problems to your garden.

Otherwise, you’ll find unwanted weeds sprouting in your garden and infections returning. Some municipal compost services handle these materials safely because they control temperature better. But home composters usually can’t.

5. Why Should Pet and Human Waste Be Excluded from Home Compost?

Pet and human waste contain harmful bacteria and parasites. Dog and cat feces, especially from meat-eaters, can carry roundworms and other pathogens. These germs survive in compost if it doesn’t get hot enough, putting your health at risk.

Backyard compost piles usually do not reach the 130°F (55°C) needed to kill these organisms safely. This means pet waste could contaminate soil or vegetables if added to home compost. Human waste is also risky because it may contain viruses and bacteria harmful to people.

Safe disposal is better for pet and human waste than home composting. You can use designated pet waste stations or flush human waste through proper sewage systems.

Some communities offer special composting services for human waste. But these need professional handling and higher temperatures.

Hot composting can destroy pathogens but requires careful management of temperature and time. It needs at least 140°F (60°C) sustained for several days, which many home systems cannot guarantee. Mistakes here can cause dangerous contamination.

Do not add pet or human waste to your compost pile. Only use waste if you have a certified hot compost system. This prevents harmful germs from spreading in your garden.

6. Which Non-Biodegradable and Synthetic Items Must Be Avoided?

Plastic, coated paper, and synthetic materials do not break down well in compost. They slowly contaminate your compost with harmful bits that do not feed soil.

For example, plastic bags can take over 1,000 years to degrade. Because of this, avoid adding plastics or coated papers to your home compost.

Dryer lint mostly breaks down nicely, but it often contains tiny plastic fibers. These fibers stay in the compost long after organic matter decomposes. To add dryer lint, use only lint from natural fibers.

These include organic cotton, hemp, rayon, silk, or wool. Avoid synthetic lint to keep compost healthy.

Avoid lint made of polyester, nylon, or other plastics. Using safe lint keeps your compost clean and helps reduce landfill waste.

Some coated cardboard, like laminated or waxed paper cups, breaks down very slowly. You can compost them if shredded small and mixed well, but expect a delay. Always shred paper and cardboard before adding them to your pile.

Check with your local recycling program if they accept bioplastic bags. Also ask if coated compost bags are allowed in the program. Not all places take these materials.

Make sure your compost pile balances green and brown materials well. Mixing materials that break down at similar rates helps microbes work better.

Try to bury synthetic-contaminated materials deep or keep them out. Keeping your compost healthy means avoiding plastics and synthetic fibers whenever possible.

Avoid adding bioplastics or coated bags if local programs reject them. Look for other ways to reduce waste that fit your area’s rules. They add little to your soil and slow the composting process.

You can use paper bags or fabric produce bags instead. These alternatives break down well and are safe for compost. They support healthy plant growth in your garden.

7. How to Recognize and Prevent Pest Attraction in Compost?

Pests come to compost when it contains food scraps or smelly items. They dig to reach leftovers and can spread contamination. Keeping your compost free of such attractants is key to avoiding this problem.

Common Signs of Pest Infestation

Pests in your compost may leave fresh holes or disturbed piles. Look for scraps of food that pests drag away or leave behind. A bad smell, like rotten or sour odors, shows decomposition is off and pests are nearby.

Other signs include droppings or tracks from rodents or insects. Flies flying around or bugs crawling in your compost means pests found food. Too much fruit or meat waste fuels this problem, so watch inputs closely.

How to Properly Store and Cover Compost

Keep compost covered with a tight lid or layer of newspaper to block pests. A sturdy bin with ventilation reduces smells while stopping scavengers like raccoons or rats. Cover fresh scraps immediately with a brown layer such as dried leaves or shredded paper.

Proper layering helps balance moisture and smell, limiting pest access. Store your compost in a shaded area. This slows fly breeding.

It also stops the pile from becoming too wet. Moisture around 40-60% keeps microbes active but keeps pests discouraged.

• Secure bin lids or use wire mesh screens
• Add carbon-rich materials daily to cover food scraps
• Turn compost regularly to aerate and speed decomposition
• Keep compost out of reach of pets and wildlife
• Check for unwanted items before adding material to the pile
• Place bins away from house walls and trash bins
• Maintain pile temperature between 130, 160°F to discourage pests

Following these simple steps lowers pest risks by cutting off easy food access. It also helps ensure your compost smells earthy, not foul, and breaks down cleanly.

Steps to Take After Pest Intrusion

Remove any spoiled or smelly compost parts pest have disturbed. Rake and cover the pile with dry browns to mask odors and discourage return visits. Make sure not to add food scraps without covering them immediately after.

Consider adding pest deterrents like predator urine or planting strong-scented herbs nearby. Repair holes around the bin or use hardware cloth to block entry points. Regular inspections can stop a small pest problem from turning into a bigger one.

8. Can Some Restricted Items Be Used with Care in Compost?

Some items are okay in small amounts but can cause trouble if added in large quantities. Coffee grounds, eggshells, and citrus peels fall into this group. Wood ash is another item with specific limits for safe composting.

Using Coffee Grounds and Tea Leaves

Coffee grounds and tea leaves make good compost ingredients. They have nitrogen, which feeds microbes that break down waste.

Remove coffee grounds and tea leaves from paper filters or tea bags first. Only add paper if it’s unbleached and has no staples.

Add coffee grounds and tea leaves in small amounts to your compost. This helps balance green and brown materials.

Too much coffee grounds can make the pile too acidic, slowing decomposition. Spread them thinly and mix well with dry leaves or shredded paper.

• Remove coffee grounds from filters before adding
• Rip or crush tea bags to speed breakdown
• Mix grounds evenly with dry brown materials
• Avoid piles with only coffee grounds, they smell and compact
• Use up to one cup of grounds per square foot of compost surface

Keep coffee and tea balanced with carbon materials to avoid sour smell.

Adding Wood Ash Safely

Only hardwood ash can be added to compost, and only in small amounts. Avoid coal or charcoal ash because they can contain harmful chemicals. Wood ash raises the pH of your compost pile.

It adds potassium and calcium. This helps if your pile is too acidic.

Sprinkle no more than one cup of wood ash per 10 square feet of compost surface. This helps keep the pH balanced without turning the pile too alkaline.

Don’t add ash if your compost already has neutral or high pH. Avoid ash if you plan to use the compost for acid-loving plants.

Mix ash thoroughly into the pile instead of dumping it on top. This avoids creating dry, grey patches that slow decomposition.

Managing Small Amounts of Citrus and Eggshells

Small amounts of citrus peels are okay but avoid adding large quantities. High acidity and natural oils in citrus can slow compost breakdown and repel beneficial microbes. Always chop peels into small pieces to speed decay.

Eggshells add calcium, which helps stabilize the compost. They take longer to break down, so crush them well before adding.

Avoid adding whole shells to your compost pile. They slow down the process and attract pests if left large.

• Chop or shred citrus peels before composting
• Add no more than 10% citrus by volume
• Crush eggshells finely for faster breakdown
• Mix citrus and eggshells well with other compost materials
• Cover fresh layers of citrus and eggshells with dry leaves or straw

Avoid large piles of citrus or eggshells. Chop and mix them well into your compost.

Step-by-Step Action Plan for Safe Home Composting

Follow these steps to avoid common mistakes and keep your compost healthy. Check each step’s result to see if your pile stays balanced and pest-free.

1. Before you start: Remove all meat, fish, dairy, and bones from your waste. This prevents bad smells and pests right away.
2. Day 1: Sort out citrus, eggshells, and bread before adding scraps. Use these only sparingly to avoid slowing decomposition.
3. Week 1: Keep yard waste free of treated wood, diseased plants, and large branches. Chop plant material smaller to speed breakdown.
4. Week 2: Never add pet or human waste to your compost pile. This stops harmful germs and protects your family’s health.
5. Month 1: Check the pile for any plastics, metals, or synthetic materials. Remove anything that won’t break down naturally.
6. Month 2: Turn your compost regularly to keep it aerated and monitoring for pests. Bugs show up, adjust your materials or cover the pile right away.
7. Month 3 and beyond: Add coffee grounds or citrus in small amounts. Only use them if your pile stays hot and balanced. Watch for changes in smell or texture.

Frequently Asked Questions

Which Vegetables Should Not Be Composted?

Avoid composting diseased or pest-infested vegetables to prevent spreading problems. Avoid using lots of onion and garlic in your compost. They can slow down breaking down.

They also keep helpful worms away. Use kitchen scraps carefully to keep compost healthy.

How Often Should You Pee on Your Compost?

It’s best not to pee directly on your compost pile. Human urine contains high nitrogen, but it can cause bad smells and imbalance. Instead, use a balanced mix of greens and browns to keep your compost working well.

What Are 5 Items That Should Not Be Composted?

Meat, dairy, bones, pet waste, and synthetic materials shouldn’t go into compost. These items attract pests, cause odors, or don’t break down properly. Stick to plant scraps and yard waste for best results.

Can You Put Coffee Grounds in Compost?

Yes, coffee grounds are great for compost and add valuable nutrients. Remove paper filters or pods before adding them. They break down well and help feed your garden.

Can You Compost Citrus Peels Safely?

You can compost citrus peels, but use them sparingly. Their acidity can slow down composting and affect microbes. Chop them up and add with other materials to keep a good balance.

Are Cooked Food Scraps Okay for Compost?

Avoid adding cooked food scraps to compost bins. They often attract pests and can create bad smells. Stick to raw vegetable and fruit scraps for safer, cleaner composting.

Final Thoughts

You can keep your home compost pile healthy by avoiding harmful materials. Start with clean, safe scraps and watch your compost improve. Now, check your bin for any banned items and remove them today.