The Monster in Your Garden

Most people have seen it. It surrounds brooks, rivers, streams, and houses. It will take over your land, one square inch at a time, preventing organisms from surviving. Once it comes, it almost never leaves. This demon is your worst nightmare. It will prevent you from selling your house, it will destroy your land, it is Japanese Knotweed also known as Fallopia japonica.

Japanese knotweed is native to East Asia in Japan, China, and Korea. This plant grows rapidly and spreads quickly as well with up to 2 meters in one season. Its underground root system can even stretch for 7 meters! 

Japanese knotweed roots

It frequently grows in ecosystems where temperatures are relatively moderate, rather than extremely hot or cold. Commonly found on roadsides, waste places, and near small bodies of water, it forms thick, dense colonies that crowd out any other plant species. Today, it is considered one of the top worst invasive species in the world. Its success is thanks to its tolerance of a very wide range of soil types, pH, and salinity.

Japanese knotweed is listed by the World Conservation Union as one of the world’s most invasive species. It was first introduced to Britain by the Victorians in the 100s as an ornamental garden plant, but now England spends over 2.8 billion dollars a year attempting to fight it annually. It increased the construction of the 2012 Olympic Stadium by over 70 million dollars! Japanese knotweed has invaded countries such as New England, Australia, and Tasmania. So far, the monster has been found in 39 out of 50 states in the US and 6 Canadian provinces. Japanese knotweed was subsequently introduced to the U.S. for use in ornamental hedges and for erosion control. The Japanese knotweed spreads is entirely through the deliberate or accidental movement of rhizome fragments or cut stems. It has an extraordinary ability to spread vegetatively, a process by which new organisms arise without production of seeds or spores, from crown, stem and rhizome (underground root).

Montclair is one of the sad towns that has been attacked by the monster. Japanese knotweed is located in our very own High School Amphitheater!! Montclair's own STEM department and a professor from MSU worked together to measure rates of photosynthesis, transpiration, and how the Japanese knotweed affected fresh water levels.

Toney's Brook in the amphitheater. The knotweed gets cut back every year for graduation but of course it grows back.

How do you know if you have the monster in your garden? Well that’s what we are here for! Japanese knotweed has hollow stems with distinct raised nodes giving the plant the appearance of bamboo, despite the plants not being closely related. The stem reaches a height of 3-4 meters each year, however smaller plants are everywhere too. The leaves are a broad oval shape with a base that is 7-14 cm long and 5-12 cm wide. The flowers are small, cream/white in color and are produced in late summer/early fall.

One of the most common ways to get rid of the monster is to eat it. A favorite recipe is Japanese Knotweed bread. This recipe was brought to us by Herbalpedia. In order to create this fabulous recipe you will need:

Materials

2 cups unbleached flour
½ cup sugar
1 ½ tsp baking powder
1 tsp salt
1 egg
2 Tbsp salad oil
¾ cup orange juice
¾ cup chopped hazelnuts
1 cup sweetened Japanese Knotweed Purée

Process

Preheat oven to 350F. Sift dry ingredients together into a large bowl. Beat the egg white with the oil and orange juice. Add along with hazelnuts and purée to dry ingredients. Do not mix until all ingredients are added, and blend only enough to moisten. Do not over mix. Spoon gently into buttered 91/2-by-5-by-3-inch loaf pan. Bake about 1 hour or until a straw or cake tester inserted in the center comes out dry. Cool by removing from pan and placing it on a rack. For muffins, spoon into buttered muffin tins and bake about 25 minutes.

By Brigie Coughlin and Samantha Chee