Composting is a brilliant way to recycle garden waste and feed your soil—but what about composting diseased plants? It’s a common question, and the answer isn’t always black and white. Understanding how to compost diseased plants is essential for maintaining a healthy garden.
Here’s what you need to know about composting diseased plant material without risking the health of your garden.
Can Diseased Plants Go in the Compost Bin?
In short: sometimes, but it depends on the disease and your composting setup. According to gardenorganic.org.uk, some diseased plants can be added to your compost, while others should be handled with caution, especially when considering how to compost diseased plants effectively.
Certain pathogens can survive the composting process—especially in home compost bins that don’t always reach the high temperatures needed to kill them off. Adding infected material could risk spreading disease around your garden when you use the compost later on. Let’s delve into the details of composting diseased plants to ensure your composting process is both effective and safe when dealing with diseased plants.
What to Compost and What to Avoid
When it comes to composting diseased plants, it’s essential to differentiate between what can be safely added to your compost heap and what should be avoided:
- Plant materials suffering from soil-borne diseases like clubroot and white rot should not be added to a compost heap.
- Diseases that don’t need living matter to survive, such as grey mould, mildews, and wilts, may survive in a cold heap.
- Heat is a crucial factor in killing diseases, as the intense microbial activity in a compost heap helps dispose of them.
- Some diseases, like tomato and potato blight, need living plant tissue to survive and will not last long without it.
When Not to Compost Diseased Plants
Avoid composting if your plants have:
- Fungal infections like rust, mildew or blight
- Viral diseases, which can survive in living tissue
- Persistent bacterial infections
- Clubroot, honey fungus or other long-living soil-borne diseases
If you’re unsure, it’s better to be cautious. Bag up the affected material and dispose of it with your household waste instead.
When It’s Usually Safe
You can sometimes compost plants with mild or early-stage issues, as long as:
- You keep your compost hot (aim for 60–70°C if possible)
- You monitor the pile regularly and turn it often to distribute heat
- You allow compost to fully mature before using it
Best Practices for Composting Diseased Plants
Here are some guidelines to follow when composting diseased plants in your organic garden:
- Add foliage suffering from diseases like tomato and potato blight to your hot or cold compost heap.
- If in doubt about a particular plant material, it’s better to leave it out of the compost pile.
- Problematic materials can be disposed of at your local council green waste recycling facility, where composting methods are designed to eliminate harmful organisms.
Tips for Safer Composting
- Don’t compost roots of infected plants—especially if they’ve had soil-borne diseases
- Shred or cut up material before adding to help it break down quicker
- Mix in plenty of dry, brown material (like cardboard, dead leaves or straw) to balance the moisture and aid decomposition
- Keep diseased material to a minimum to reduce risk
Well-maintained compost heaps can break down many pathogens, especially fungal spores, over time. The key is heat and time.
The Bottom Line
If in doubt, leave it out. It’s not worth the risk of reintroducing plant diseases into your garden. Your compost is meant to be a health booster for your soil—not a hidden threat.
Conclusion
Composting diseased plants in your garden requires careful consideration to ensure the health of your compost pile and future plants. By following the guidelines mentioned above, you can effectively manage diseased plant materials while maintaining a thriving composting process.
If you’re unsure what’s safe to compost, or if a particular plant disease is causing you trouble, we’re happy to help. At Cowen Landscapes, we offer friendly advice and professional garden care to help keep your green spaces in great shape.
Have a gardening question? Contact us for expert advice and tips on organic gardening practices.
