Native range: Japan, China, and Korea
Invasive range: Throughout North America and Europe
Habitat: Riverbanks to roadsides, often in dense clumps where little other vegetation can survive.
Description: Fast-growing and aggressive perennial that can reach 6 or 7 feet in height. Mostly spreading through rhizomes, or roots, shoots can sprout through heavy mulch and even asphalt. Leaves are alternate, egg shaped; stems are hollow. Small white flowers bloom in late summer. The fruit, a single seed within a three-winged calyx, remains on the stem for a short time after senescence. The young shoots are edible.
It’s the 1880s. Frederick Law Olmstead, who, in his thirties, co-designed a little patch of ground in New York called Central Park, in his forties sells Boston on the Emerald Necklace, a whole new park system––and, in the process, he plants miles of parkway with a brand new import he thinks pretty and perfect for hedges, windbreaks, and erosion control. Olmstead was an abolitionist journalist. He invented landscape architecture. He made the case for preserving Yosemite Valley as a public park. He chose Japanese knotweed to line his highways. He made a big mistake. He’s not the only one.
It’s 2002. The forager Steve Brill calls knotweed “one of the premier wild foods of early spring. It is so abundant and invasive that gardeners and landscapers detest it.” Others are not so kind: this “fearsome colonizer of the peaceful lands” as the Brits call it (they should know) easily makes the Global Invasive Species List of the 100 worst invasives.
Knotweed grows fast; this clip shows one meter of growth in only three weeks. So within days it will go from tender to tough; catch it while it resembles what Brill calls a “fat, reddish asparagus stalk.” Last year’s dead stalks likely mark dense stands of new shoots. This is the best time to harvest it, though you can eat shots up to 1′-2′ tall, provided you remove the leaves and peel the bark. Related to rhubarb, it’s very sour and may act as a laxative the way rhubarb does, so use it sparingly at first.
Most importantly, be sure that any harvesting of Japanese knotweed does not result in its spread. Pieces of rhizome can stay dormant for years before sprouting. Never add knotweed to your compost or send it to a municipal compost center.
Dandy Knotweed Muffins
From Blanche Cybele Derby
author of My Favorite Plants
The best time to gather young knotweed shoots, up to about 8 inches, is in early spring. (The larger ones are tough and stringy.) Here in Massachusetts, that’s usually the end of April, though this year they were a few weeks early. Collect young Japanese knotweed stalks, up to about 8 inches. They grow like crazy, so you have to be johnny-on-the-spot to get them before they’re too high. Some people peel the outer skin off the shoots, but that can be tedious, and if you’re not careful, you may peel too much off, so I usually don’t bother.
Makes 16 large muffins
Japanese knotweed stalks to measure 2 cups, minced
1.5 cups flour
0.5 cup dandelion flower petals, stripped from their base (do not include any green parts)
1 teaspoon baking powder
1 teaspoon baking soda
0.5 cup softened butter
1 cup light brown sugar
1 teaspoon vanilla
1 cup sour cream or yogurt
Snip off the pointy tops of the knotweed stalks and mince.
Combine flour, dandelions, baking powder, and baking soda in a small bowl.
Cream 0.5 cup butter with 1 cup brown sugar until fluffy. Beat in eggs one at a time and then add the vanilla. To this mix, alternately fold in the sour cream and dry ingredients until blended. Fold in the knotweed pieces. Divide the batter into greased muffin forms.
Bake at 350˚F for 15 to 20 minutes, until the muffins test done in the center.
This recipe can be adapted to use 1/2 rhubarb & 1/2 knotweed and if dandelion petals aren’t available, pull apart red clover flowerheads and use those individual pieces. Feel free to experiment!
4 lbs (2 kg) knotweed stems, cut into chunks and leaves removed
3 lbs (1.5 kg) sugar
1 t yeast nutrient
juice of 1 orange
wine yeast (all-purpose yeast will do, but champagne yeast preferred)
enough water to make up to 1 gal (4.5 liters)
Put knotweed into a straining bag, and put bag into a sterilized bucket.
Bring the water, sugar, orange juice, and yeast nutrient to boil and pour onto bag in bucket.
Let stand, covered, till cool.
Activate the yeast and add it to the bucket.
Keep the bucket covered for about a week, till the fermentation dies down a little.
Decant into a demi-john.
Treat as for other wines from here––though if your wine retains a vibrant pink at this point, stabilizing it with sulfite when bottling it will make the hue vanish.
Steve Brill’s Japanese Knotweed Sherbet
Japanese knotweed shoots, peeled if longer than 8″ and coarsely sliced
1 1/3 c orange juice (freshly squeezed is best)
1 1/2 c apple juice or other unsweetened fruit juice
1/2 c lemon juice
1/4 c canola oil
1/4 c vegetable glycerin, honey, barley malt, or rice syrup
1 T freshly grated orange rind
2 t vanilla extract
1 t lemon extract
1 t liquid stevia (optional)
1/2 t salt
1. In a medium saucepan, simmer knotweed shoots in orange, apple, and lemon juice over medium heat, covered, until shoots are tender, about 10 min.
2. Transfer knotweed and juices to blender, and remaining ingredients, and process until smooth.
3. Chill mixture until cold (1 hr in freezer or 4 hrs in fridge).
4. Pour mixture into ice cream machine and freeze according to manufacturer’s instructions.
Makes 5 cups; serves 5.
Strawberry knotweed pie
Adapted from Wild Plants I Have Known and Eaten by Russ Cohen.
Young, spring Japanese knotweed tastes similar to rhubarb, and makes a perfect partner with seasonal fresh strawberries in this beautiful pie. Knotweed first appears in April, and by May the young stalks of 1 to 2 feet high are ready to harvest by cutting just about the woody base and removing the leaves. This is a recipe for a two-crusted pie, but we’ve also made it using only a top crust and that works nicely as well.
Makes a 9-inch pie
3-plus cups sliced strawberries
3-plus cups peeled, sliced Japanese knotweed stalks (cut stalks in half lengthwise to reduce any trapped air space inside, and then in 3/4- to 1-inch pieces, as you would cut rhubarb)
1 cup sugar
1/2 teaspoon ground nutmeg
1 teaspoon cinnamon
1/2 teaspoon ground allspice
Flour, as needed for filling and rolling
Dough for crust (below)
1. Preheat oven to 425 degrees. Mix the filling ingredients together in a bowl; if runny juice accumulates in the bowl, stir a tablespoon or so of flour into the filling to help absorb it.
2. Spread out one ball of dough with the base of your hand, then use a rolling pin to roll it out to approximately 1/8-inch thick, adding flour to the pin, counter, and/or dough if they get sticky – or roll the dough between 2 sheets of wax or parchment paper dusted with flour. Place in the pie plate. Pour filling into the pie plate. Repeat the process with the second ball of dough and cover filling (or cut into 1/2-inch strips and place over filling in a lattice pattern).
3. Place on a cookie sheet and bake for 20 minutes at 425 degrees, then 25 minutes more at 400 degrees. The pie is done when the filling bubbles over and the crust is golden. If the pie crust is getting too brown in one or two places before the rest is done, place a small piece of aluminum foil over that spot to slow the browning.
Dough for crust
1 2/3 cups all-purpose flour
Pinch of salt
5 tablespoons cold butter
5 tablespoons vegetable shortening or lard (or all butter, if preferred)
7 tablespoons cold apple or orange juice
1. Pour flour and salt into a food processor. Dice butter into small pieces and cut shortening into big pieces and add to processor, and pulse until coarsely chopped (small lumps are okay). Add cold juice and pulse until it begins to ball up.
2. Shape into two balls, wrap in wax paper or plastic wrap, and refrigerate for 30 to 60 minutes.