Japanese knotweed is an invasive plant that can be very difficult to get rid of. This bamboo-like plant spreads aggressively and its roots can grow up to 10 feet deep. Even the smallest fragment left behind can sprout new growth. So after removing Japanese knotweed from your yard, proper disposal is essential to prevent further spread.
In this guide, I’ll cover everything you need to know about disposing of Japanese knotweed in a safe and responsible manner.
Why Is Proper Disposal So Important?
Japanese knotweed is classified as an invasive plant in North America and Europe. It spreads quickly and crowds out native plants, causing damage to local ecosystems. Even worse, its deep root system can cause damage to pavement buildings and pipes.
That’s why you can’t just throw Japanese knotweed clippings in the compost or trash. Any tiny piece left behind can regrow. So it’s crucial to contain and dispose of all parts of the plant carefully.
Improper disposal spreads Japanese knotweed to new areas, worsening the problem. By understanding the plant’s life cycle and following recommended disposal methods, you can help stop its spread.
Know Your Local Regulations
Many places regulate Japanese knotweed disposal due to its invasive nature. For example:
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In the UK, it’s classified as “controlled waste” and must be disposed of at licensed landfills.
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Some U.S. states prohibit transporting it long distances or require permits.
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Many municipalities ban putting it in yard waste collected for composting.
Before disposing of Japanese knotweed, research the rules for your region. Failing to follow regulations could result in significant fines.
Recommended Disposal Methods
There are several effective ways to dispose of Japanese knotweed without spreading it further:
Air Drying
After removing the plant, let it dry out completely before disposal. This kills the plant so it won’t regrow.
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Cut the stems close to the ground and gather them for drying.
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Cover the pile with a tarp or black plastic to accelerate drying.
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Allow at least 3 weeks for thorough drying before disposal.
Onsite Brush Pile
For smaller infestations, create a brush pile of the dead stems and leaves onsite. Choose an out-of-the-way spot on your property away from any water sources. Over time, the pile will decompose.
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Avoid making brush piles during or after flowering as seeds may spread.
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Monitor the pile and treat any regrowth quickly with herbicide.
Bag for Landfill
For larger volumes or when local regulations require, bag up plant parts and dispose of at a landfill.
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Use thick, durable plastic bags that won’t break open.
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Transport bags securely contained, like in a truck bed with cap.
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Call ahead to ensure your local landfill accepts Japanese knotweed.
Controlled Burning
In some areas, you can burn dried knotweed as an alternative disposal method.
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Allow cut stems to dry completely before burning.
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Follow all local open burn regulations.
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Never leave a fire unattended and have water on hand.
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Allow ashes to fully cool before disposal.
What Not to Do
Avoid these disposal methods that spread Japanese knotweed:
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Composting – Stems, roots, and seeds survive the composting process.
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Regular trash – Landfills don’t reach high enough temperatures to kill Japanese knotweed.
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Dumping in vacant lots, woodlands, or waterways – Spreads infestation to new areas.
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Using contaminated soil or mulch – Transports roots and seeds on shared equipment.
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Long-distance untreated firewood – Regulations often prohibit moving untreated firewood.
Follow Prevention Measures
Stopping Japanese knotweed before it spreads is ideal. Here are some prevention tips:
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Learn to identify Japanese knotweed and avoid purchasing or transplanting it.
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Clean tools, boots, and tires after working in infested areas to avoid transporting soil with roots or seeds.
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Monitor your property frequently and remove any Japanese knotweed sprouts quickly before they spread.
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Tell neighbors about Japanese knotweed’s impacts and disposal requirements so they don’t unknowingly spread it.
When to Hire a Professional
For severe infestations, you may need to hire a professional Japanese knotweed removal and disposal service. Companies may have stronger herbicides, tools to remove extensive roots, and ability to haul large volumes to a licensed landfill.
Though hiring a pro costs money, it guarantees proper disposal. Reputable companies also offer multi-year guarantees if the Japanese knotweed regrows.
Disposal Tips for Aquatic Varieties
Japanese knotweed also has several aquatic varieties that can be quite invasive in wetlands and waterways. Here are some key tips for disposing of these safely:
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Remove from water and allow to fully dry on land before disposal.
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Clean any watercraft, trailers, and equipment after use in infested waters.
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Bag and dispose of aquatic knotweed at a landfill, not in compost.
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Never dump aquarium plants into or near any waterway – dispose in the trash.
Be Diligent and Patient
Getting rid of Japanese knotweed takes persistence. You’ll need to monitor areas carefully for years after removal and be ready to promptly treat any regrowth.
But by understanding its lifecycle, using recommended disposal methods, and not moving soil or plant materials from infested sites, you can help eliminate Japanese knotweed. With diligence and patience, you can reclaim your property from this damaging invasive plant.
How can I safely dispose of soil that contains Japanese Knotwood rhizomes?
I live in Saco and am in the process of a multi-year (lifelong?) effort to control the spread of Japanese Knotweed on my property, using a combination of methods. My property abuts a community garden/park, which is infested, so I have no illusions of ever eradicating it but am trying to control its spread into my yard. Chemicals are not an option, as I’m against them and there’s a creek/storm drain between my property and the park.
I’m planning to dig a trench to prevent the knotweed from spreading into my lawn area. Whatever knotweed spreads underground past the trench will get mowed. My question: where and how do I safely dispose of the dug-up soil with rhizomes in it? I want to communicate to the landfill folks that this can’t go on compost and shouldn’t be used for fill dirt but considered as trash. I can try removing the visible rhizomes and double bag them separately, but there will still be remnants left.
The strip I plan on digging up has been mowed regularly for 5 years, so the rhizomes are relatively weak, and I plan to dig from mid to late April before shoots come up. Any guidelines on how deep to dig, and where to dispose?
Tori Lee Jackson, Extension Professor of Agriculture and Natural Resources
Digging out the rhizomes is not recommended because Japanese Knotweed can create a new plant from very tiny pieces of plant left in the soil. Repeated mowing/cutting (up to once/week ), raking up those plant parts and placing them in black garbage bags, and then leaving those tied bags in the sun for a few weeks should be sufficient to kill the stems and leaves. Even then, it should not go into a compost or burn pile. Not all landfills accept invasive species, so calling your local transfer station ahead of time is recommended.
How to get rid of Japanese knotweed | Knotweed removal UK
FAQ
Where to throw away Japanese knotweed?
For Japanese knotweed to be disposed of off-site, it must be sent to a permitted landfill site or incineration facility that can safely handle Japanese knotweed and other invasive plants. As it is considered a hazardous material, Japanese knotweed can only be handled by licenced and registered carriers.
What to do with dead Japanese knotweed?
Dispose of the stalks and don’t let them fall on the ground. They can take root. I would let them dry out on asphalt and then break them up and put them in the rubbish bin.
Can you put Japanese knotweed in the bin?
put the knotweed in garden sacks in the place you cut it down. not put it in any bin or move it across the garden. make sure the bag does not have soil in it.
How do you destroy Japanese knotweed?
Glyphosate is the herbicide of choice for controlling knotweed. It is effective, has no soil activity, it is readily available, and somewhat inexpensive.