Japanese knotweed is an invasive plant species that quickly takes over large areas of land, damaging buildings in the region . Its growth may also negatively affect the visual appeal of outdoor spaces, as each knotweed plant can grow up to 15 feet, developing bamboo-like stems. That’s why knowing how to get rid of Japanese knotweed is important. Not all knotweed treatments can eliminate the plants permanently, but they can prevent their regrowth for a while.

1. Use corn gluten meal
A by-product of the corn milling industry, corn gluten meal is predominantly used as a fertiliser. This is also a safe remedy. It acts as a herbicide, controlling the growth of Japanese knotweed by preventing the plant from germinating and spreading. To use this remedy, one can spread corn gluten evenly over the area where knotweed growth is most dominant and water it.

2. Apply vinegar
This common household ingredient can be a natural herbicide for Japanese knotweed. Vinegar contains acetic acid, which can kill knotweed quickly. To use the remedy, one must combine one part vinegar with two parts water and then apply the solution directly to the plant’s leaves. While this will eliminate the invasive plants, the remedy is safe for the environment and will work as knotweed treatment for smaller regions.

3. Pour boiling water
An easy method to deal with Japanese knotweed is to pour boiling water on it . The water can scald the roots and leaves, preventing them from regrowing. All one has to do is heat a large pot of water until it boils and then pour it over the knotweed. It’s that simple. But one must practice caution and wear protective gear, like gloves, when handling boiling water to avoid burns.

4. Use salt
This kitchen ingredient can also help curb the spread of Japanese knotweed. When the plant comes in contact with salt, it can start withering. Here, sprinkling salt over the knotweed should do the trick.

5. Apply lemon juice
In addition to being a common cleaning and cooking ingredient, lemons can help control Japanese knotweed growth. Lemon juice has citric acid, which can help damage and kill the plant. To use it as a remedy, one can combine lemon juice with water and apply the concoction directly to the plant’s leaves.

6. Try herbicides
When looking for herbicides, one should pick those containing glyphosate for better results. Also, late summer is the ideal time to try this method. During application, one must wear rubber gloves and protective clothing to avoid contact with the powerful herbicide. Then, one should cut the plant roughly 3 to 4 inches above the ground, as this will stimulate new growth that can readily absorb the herbicide. After that, once the new growth sprouts from the sliced stems, one should carefully lace the growths with herbicide. Eventually, the growth will turn yellow and wither. This herbicide treatment must be repeated every few months if necessary.

7. Cover growth with tarps
Covering invasive plant species with tarps could help curb their growth. But, tarps may take several years to eliminate Japanese knotweed. If one can wait that long, spring is the best time to begin with this method, as it is the start of knotweed growing season. 

First, one must prepare the area by trimming mature weed canes to the ground, removing debris, and bagging them to prevent them from taking root. Then, the region should be covered with soft materials like leaves, mulch, or grass clippings. After that, one must cover the area completely with thick black sheets of plastic or heavy non-canvas tarps. If one overlaps two tarps, one must place them over each other for 2 feet. The plastic must extend 5 to 10 feet outside the boundary of the knotweed growth. One should also use rocks or other heavy materials to weigh down the tarps and stop them from blowing away. Then, one should remove and trample any new shoots as these might push against the tarps. After about five years, the smothered knotweed and roots should have withered. Then, one can remove the tarp and replant the area with whichever shrubs, plants, and grass one likes.

8. Trim the plants
This method works best when combined with other Japanese knotweed treatments. To try it, one must trim the plant to the ground throughout the growing season so it is unable to photosynthesise. Then, one should gather all the cut plants in a bag and get rid of them. Leaving them as is could propagate new growth. One must also monitor and repeat this process every week and clip off any new shoots that might appear.

9. Dig up roots
Another way to prevent Japanese knotweed from invading a space is to dig up the roots where the shoots vigorously grow. One must find the plant’s underground stems and dig them up. Some might be as deep as a foot or more. Following this, proper disposal of the uprooted plants is also essential to prevent their reoccurrence.

10. Hire an expert
DIY Japanese knotweed removal can help one save some money, but some knotweed plants can be lodged deep into the ground, making them impossible to remove with at-home equipment. In such cases, one should hire a professional for the job. They will have the right tools and products to kill Japanese knotweed and prevent regrowth for a long time. If one doesn’t know a professional, they can log onto a search engine, look up knotweed treatment services in their area, and get quotes. Some service providers may also offer a money-back guarantee if the knotweed regrows.