What Does Japanese Knotweed Look Like?

Have you ever seen a weed in your yard and wondered what it was? If so, you’re not alone. Many homeowners struggle to identify different types of weeds, and that’s where this blog post comes in handy.

Anyone can tell you that it’s important to be able to identify potential problems with your property. You also know that keeping your lawn and garden looking nice can be a lot of work.

One of the things you need to be on the lookout for is Japanese Knotweed, which is a highly invasive species and can quickly take over an area if not dealt with. So, what does Japanese knotweed look like? Keep reading to find out!

What is Japanese Knotweed?

Japanese Knotweed, or Fallopia Japonica, is a fast-growing perennial plant that is native to East Asia. It was first introduced to North America in the late 1800s as an ornamental plant, and it has since become one of the most aggressive invasive species in the country. Japanese knotweed can grow up to 10 feet tall, and grows up to 4 inches in a single day.

If you discover that this plant has infested your property, remove it carefully or have a professional do it since the rhizomes can produce new shoots many feet away from the primary plant and take over an area in no time.

There are a variety of regulations in place for the development and disposal of Japanese Knotweed. For example, you’re never allowed to dispose of it on the side of the road or throw it in a landfill. This weed is so prolific that it can grow from these locations, and become an even bigger problem for yourself and your neighbors.

You are only allowed to burn the weed or deliver it to a legitimately licensed landfill. If you’re not sure what to do, contact your local authorities about any applicable Japanese Knotweed laws.

Where Does Japanese Knotweed Grow?

´╗┐Japanese knotweed is most commonly found growing along roadsides, in vacant lots, and in other disturbed areas. Japanese Knotweed is difficult to control once it becomes established, and it spreads via seed or root and forms dense thickets that crowd out other plants, lowering biodiversity in a garden or forest area.

The best way to prevent the spread of Japanese knotweed is to remove it from your property as soon as you see it.

How to Identify Japanese Knotweed

If you think you may have Japanese knotweed on your property, it’s important to take action immediately. This plant can cause serious damage to your home, and it’s important to take steps to remove it before it gets out of control.

The first step is to know exactly what Japanese Knotweed looks like and how to identify it, so you can quickly make an informed decision as to how to eliminate it.

Visual Characteristics

The leaves are large and resemble heart-shaped ovals, with serrated, wavy edges that look like the teeth of a saw. The leaves are green and have dark red veins at times.

The stems resemble bamboo and have rings and purple splotches. Leaves sprout in an alternating zig-zagging pattern from the stem nodes. The nodes produce new plants when they reach the surface of the stem, or come in touch with water. On the inside, the stems look like bamboo, and if you break one off, the inside will be hollow.

The plant gets its name from the small white flowers that bloom in clusters, which resemble knots when they are in bud.

Growth Stages

In the fall, Japanese Knotweed blooms with tiny green-white flowers that are carried by the wind. These flowers grow straight up in a pointy cluster 2 to 6 inches long. Before these bloom in the summer, you can find white or pinkish spindle-shaped fruits that are around 1/3-inch in length.

New leaves created by the Japanese Knotweed start off red, but then they turn green with red veins, and eventually just become fully green. If you see red leaves, you’ll know it’s a relatively young plant.

Other Unique Traits

The most remarkable feature of Japanese Knotweed is its huge size and rapid development. It can potentially grow up to 4 inches each day, which is a significant difference from the other common weeds! So, if you see a weed that seems to grow right in front of your eyes, chances are it’s Japanese Knotweed.

Plants That Look Like Japanese Knotweed

It might be difficult at first to spot Japanese knotweed. Due to the resemblance of their foliage and nodule-covered stems, many other plants are labeled as knotweeds. 

The following plants are sometimes thought to be Japanese Knotweed: Dogwood, Lilac, Houttuynia, ornamental bistorts such as Red Bistort, Lesser Knotweed, Himalayan Honeysuckle, and Russian Vine.

However, after a day or two you will know whether your backyard weed is one of these or Japanese Knotweed, because the knotweed will outgrow all of them very rapidly.

How to Get Rid of Japanese Knotweed

While it’s important to be able to identify this invasive plant, it’s also crucial that you know how to get rid of Japanese Knotweed if you do happen to find it on your property. The good news is that there are many methods available to homeowners and professionals alike for eliminating this weed.

The most effective approach to eliminate Knotweed on your property is to utilize chemical herbicides. RoundUp, for example, is an excellent weed killer for Japanese knotweed; really, any glyphosate-containing herbicide will suffice. You’ll need apply the herbicide at least twice, 2 weeks apart each time, before you notice any results. This is especially true for plants taller than 1 foot.

If you don’t want to use pesticides, digging out the Knotweed with a spade or hoe is an option. It may take a long time and hard work, but if you set your mind to it, it’s totally doable! This method is relatively simple, and has the best rate of success, so we suggest trying this first and then using a weed killer.

Final Thoughts

Japanese knotweed is an invasive plant that can cause a lot of damage. If you think you have this weed on your property, it’s important to take action and get rid of it as soon as possible. With a full infestation, it’s best to call in a professional. However, there are some things you can do to help control the spread of this invasive plant.

It is important to be able to identify this plant, as it can be difficult to remove once it becomes established. The visual characteristics and growth stages of Japanese knotweed are described in detail in this article above. We’ve also shared some tips on how to get rid of Japanese knotweed if you find it on your property.

Be sure to keep an eye out for Japanese knotweed and educate your friends and family about how to identify it. With a little bit of effort, we can all work together to keep this weed from taking over our yards and communities. If you’re looking for more information or want help getting started on a treatment plan, please don’t hesitate to reach out. We’d be happy to help! Thanks for reading!