Composting is a popular way to improve soil health and boost plant growth, but it’s not always a guaranteed success for your garden. If compost isn’t managed correctly, it can lead to problems that affect your plants’ ability to thrive.
Understanding how compost can negatively impact your harvest is key to avoiding common mistakes that gardeners often make. By learning what to watch out for, you can make smarter choices and create a healthier environment for your plants.
Too much oily kitchen waste contaminates compost

You should avoid adding large amounts of oily kitchen waste to your compost. Excess oil can create a greasy layer that reduces airflow.
When your compost becomes too oily, it can slow down the breakdown process. It may also cause bad odors and attract unwanted pests.
A small amount of oil is usually okay in an established pile. Just be sure to mix and aerate your compost regularly to keep it healthy.
Adding meat or dairy attracts pests and rodents

If you add meat or dairy to your compost, you might notice unwanted visitors. These scraps can attract pests like rats, raccoons, and flies.
Pests can spread diseases and disrupt your composting process. They also make your garden less enjoyable.
To keep pests away, avoid putting meat and dairy in your compost. Stick to plant-based scraps for a safer, cleaner harvest.
Including diseased plants spreads pathogens

If you add diseased plants to your compost, you risk spreading harmful pathogens. These pathogens can survive and infect your garden later.
Even though composting involves microbes that fight disease, some pathogens may persist when conditions aren’t ideal.
To protect your harvest, avoid composting plants that show signs of disease. This helps keep your soil and plants healthier.
Using weeds that have gone to seed spreads unwanted plants

If you add weeds that have already produced seeds to your compost, those seeds can survive the process. This means you might end up spreading them back into your garden.
To avoid this, try cutting the weeds before they go to seed. You can also let your compost get hot enough to kill seeds, but not all home setups reach those temperatures.
Being careful with seed-bearing weeds helps keep your garden free of unwanted plants.
Adding human or pet feces risks harmful bacteria

You should avoid adding human or pet feces to your compost. They can contain harmful bacteria and parasites that are unsafe for your plants and health.
Even when composted, these wastes can harbor pathogens that may not fully break down. This can lead to contamination of your soil and crops.
Keeping your compost free of animal and human waste helps ensure safer, cleaner harvests for your garden.
Overwatering the compost pile causes bad odors

If your compost is too wet, it can create an anaerobic environment. Without enough oxygen, bad smells start to develop.
You might notice a sour or rotten odor. This happens because excess moisture slows down the breakdown process.
To fix this, add dry, carbon-rich materials like newspaper or leaves. Also, turn your pile regularly to improve airflow and keep odors at bay.
Imbalance of greens and browns stalls decomposition

If your compost pile has too many greens, it can become soggy and smelly. Greens provide nitrogen, but without enough browns, decomposition slows down.
On the other hand, too many browns, like dry leaves or straw, make your pile dry and slow to break down.
To keep things moving, aim for a balanced mix of roughly two parts browns to one part greens. This balance helps maintain airflow and moisture, speeding up composting.
Not chopping scraps into small pieces slows breakdown

When you don’t chop your kitchen scraps, decomposition takes longer. Larger pieces are harder for microbes to break down quickly.
By cutting scraps into smaller bits, you give decomposers more surface area to work on. This speeds up the composting process and helps you get usable compost sooner.
Slower breakdown can lead to unwanted smells and attract pests. Keeping scraps small helps keep your compost healthy and efficient.
Composting citrus fruits can harm soil microbes

If you add too much citrus to your compost, the acidity can increase. This change in pH may make it harder for beneficial soil microbes to thrive.
Some microbes are sensitive to acidic conditions, so your compost’s balance could be disrupted. That might slow down decomposition or affect nutrient availability.
Using small amounts of citrus is usually fine, but avoid large piles. This helps protect the microbial life that supports your plants.
Failing to turn the pile reduces oxygen and slows decay

If you don’t turn your compost pile regularly, oxygen can’t reach all the materials. This lack of air slows down the microbes that break down the organic matter.
Turning your pile every few days helps keep oxygen flowing and speeds up decomposition.
Without enough oxygen, your compost may take much longer to become rich soil, which can hurt your harvest.
Including glossy or heavily printed paper adds toxins

If you add glossy or brightly colored paper to your compost, it can introduce toxins. These papers often contain inks and coatings with heavy metals or chemicals that don’t break down well.
Avoid using magazines, flyers, or glossy advertisements in your compost pile. Stick to plain paper like newspaper or office sheets to keep your compost safe for your plants.
Adding synthetic chemicals or pesticides harms compost quality

When you add synthetic chemicals or pesticides to your compost, you disrupt the natural biology that breaks down organic matter. These chemicals can kill beneficial microbes essential for healthy compost.
This damage reduces the nutrient value of your compost and can harm your plants when applied to soil. To keep your compost thriving, avoid using synthetic fertilizers or pesticides in the mix. Your garden will thank you for it.
Putting bones in compost attracts animals and decomposes slowly

If you put bones in your compost, you might notice unwanted visitors like raccoons or rodents. These animals are drawn by the smell and can disturb your compost pile.
Bones also break down very slowly, sometimes taking years. This can slow the overall composting process and leave hard bits in your soil.
To avoid this, try not to add bones directly. Crushing small bones can help, but it’s usually better to skip them altogether.
Including cooked foods creates unpleasant smells

When you add cooked foods like pasta, bread, or greasy leftovers to your compost, it can cause bad odors. These smells happen because cooked foods attract pests and bacteria that break down fats and proteins.
This not only makes your compost unpleasant but can also slow down the composting process. To keep your compost healthy and odor-free, stick to raw plant-based scraps instead.
Adding pet fur in large amounts disrupts microbial balance

If you add too much pet fur to your compost, it can upset the natural microbial balance. Pet hair breaks down slowly, so large amounts may slow decomposition.
This can reduce the effectiveness of beneficial microbes that help turn compost into nutrient-rich soil.
Using small amounts of pet fur occasionally is fine, but avoid adding heavy layers to keep your compost healthy and active.
Not monitoring temperature fails to kill pathogens

If you don’t track the temperature of your compost, harmful pathogens may survive. To kill weed seeds, larvae, and bacteria, your compost needs to reach at least 131°F (55°C) for several days.
Without this heat, harmful organisms can thrive and later affect your plants. Keeping an eye on temperature helps ensure a safer and more effective compost pile.
Leaving large pieces causes uneven composting

If you leave large pieces in your compost, they will break down much slower than smaller ones. This can cause some parts of your compost to be ready while others are still raw.
Uneven compost means your soil might get inconsistent nutrients. It can also make your compost less pleasant to work with in your garden.
Chopping or shredding materials helps speed up decomposition and creates a more uniform compost for your plants.
Adding too much fresh grass clippings creates slime

When you add a large amount of fresh grass clippings to your compost, it can quickly turn slimy. This happens because the clippings are high in moisture and break down fast, causing the pile to become wet and compacted.
If your compost turns slimy, it may start to smell unpleasant and stop decomposing properly. To prevent this, mix grass clippings well with dry materials like leaves, and avoid adding too many at once.