Gardening expert says adding summer 'leftover' to compost may 'harm plants'

For gardening enthusiasts, transforming kitchen and garden waste into nutrient-rich compost is a rewarding endeavour. It's an excellent method of recycling, reducing landfill waste and creating a valuable soil enhancer for your plants.

However, not all materials are suitable for composting. The composting process depends on the decomposition of organic matter, but certain items can disrupt this process, attract pests, or even contaminate the entire heap.

To maintain a healthy and productive compost pile, it's essential to know what to exclude. Fiona Jenkins, a UK-based gardening expert with more than 25 years of experience in the industry from , advises against adding certain items to your compost heap.

What not to put on compost

Meat and milk products

While meat and milk products are biodegradable, they should be kept out of your garden compost pile. These items can draw in a range of unwanted pests that could damage your garden and become a significant nuisance.

Moreover, these pests may leave behind undesirable extras, such as faeces.

Treated wood or sawdust

Treated wood products such as sawdust or scraps should be kept away from your compost heap. The chemicals used in their treatment can damage the quality of your compost and may render it unusable in the future.

However, untreated woods are perfectly safe for composting.

Baked goods

Avoid adding items like cookies, cakes and other baked treats to your compost heap. These can draw unwanted pests to your garden, much like meat and dairy products.

Sweet baked goods can also lure a variety of undesirable insects, including ants and wasps.

Acidic foods

Foods with high acidity levels, such as pickled foods, tomatoes, and citrus fruits, should not be added to your compost heap. High acid content can destroy the beneficial bacteria that aid in breaking down the materials in your compost pile, thus reducing its effectiveness.

Greasy or oily foods

Your compost heap requires certain moisture levels to ensure proper decomposition. Grease and oils can disrupt this moisture balance.

Therefore, it's crucial to refrain from adding greasy or oily items to the compost heap. Additionally, the smell of grease can attract insects and other pests.

Human or pet waste

While organic waste from humans and pets can technically be composted, it's crucial to consider the end use of your compost. Do you really want to spread such waste across your garden?

Moreover, these types of waste often emit unpleasant odours, which could make your garden less enjoyable.

Certain types of waste can also pose health risks, so it's best to steer clear of them in your compost pile.

Weeds

Garden waste typically forms a significant portion of any compost heap. It's beneficial to add plant matter, twigs, leaves, and other greenery to your compost.

However, it's advisable to refrain from adding weeds. Weeds have the potential to take root within the compost heap and proliferate through the organic waste, compromising the quality of your compost.

Insect-infested or diseased plants

A compost pile needs to reach high temperatures to effectively kill off insects and diseases. Unfortunately, it's unlikely that your compost bin will achieve the necessary heat levels to eradicate these pests and diseases.

This means they could survive within the compost heap, rendering it unfit for use.

Charcoal ash

While it might seem like a good idea to dispose of your barbecue leftovers on the compost heap, it's best to refrain from doing so. The ash from charcoal is rich in sulphur, which can render your compost pile excessively acidic for most plants.

Moreover, charcoal is frequently laced with various chemicals that could potentially harm your plants.

Cigarette ends

Many cigarette ends are made from plastic and generally take an extended period to decompose. Furthermore, cigarettes are laden with chemicals that could inflict damage on your plants when the compost is applied.

Leather goods

It's advisable to keep leather items off your compost heap due to the oil finishes and numerous other chemical components they contain. Elements such as dyes, additives, and chemical tanning agents can be detrimental to the compost heap and may pose a risk to plants

The additives in leather goods also mean that they will take a considerable time to break down. Therefore, it's best to steer clear of adding leather products to the compost heap altogether.

Coloured paper

Paper heavily printed with coloured ink or marked with marker pen should not be added to the compost bin. Any material with a high ink content could harbour metals and other toxins that could contaminate the compost.

Creating successful compost

Fiona explained: "Creating a successful composting heap is all about balance and understanding the needs of the decomposition process. By being mindful of what you add to the pile and knowing what to avoid, you can ensure a steady supply of beneficial compost for your garden.

"Steering clear of meat and dairy, treated wood, baked goods, high-acid foods, greasy items, waste, weeds, diseased plants, charcoal ash, cigarette butts, leather and heavily inked paper will prevent a host of problems such as unwelcome pests, unpleasant odours, and the potential contamination of your soil. With this knowledge under your belt, you can complete the process safely and you will be well on your way to nurturing a thriving and healthy garden with your own homemade compost."