The plant that could cost you your home

The spread of Japanese knotweed is cause for concern for all homeowners

If, like me, you are not particularly green-fingered, you might think that one plant looks pretty much like another. In which case you are in danger of missing a silent assassin gaining strength within your garden.

Japanese knotweed looks like lots of other weeds to the untrained eye, but it has the power to ruin your home and cost you thousands of pounds.

Pity the couple in Hertfordshire that were told a couple of years ago that their £300,000 four-bed home needed to be demolished in order to treat the scourge of Japanese knotweed that had penetrated their walls.

The plant had spread from waste ground near the newly-built property and quickly advanced the length of the garden to enter their home through walls and skirting boards. Surveyors told them that the value of the property had dropped to just £50,000, and that the only way to effectively remove the scourge was to knock the house down, treat the plant and then rebuild.

And imagine the disappointment of the home seller who saw his deal fall through within weeks of exchange because a tiny 3cm piece of Japanese knotweed had been found in his garden. His buyer’s lender panicked and refused to lend the mortgage.

These are clearly extreme examples but Japanese knotweed is almost always a problem for homeowners (and potentially their neighbours).

What exactly is Japanese knotweed?

Japanese knotweed has been in the UK since the 1800s, having been introduced as an ornamental plant by the Victorians.

It looks pretty innocuous, like many plants or weeds, and is described by the Environment Agency as lush green in colour with shovel shaped leaves and a stem that looks like bamboo. It also produces white flowers in autumn and grows rapidly, up to 10cm a day.

It spreads like wildfire through its stems underground, growing a metre in a month and potentially causing heave below buildings.

Once the concrete or tarmac cracks from the heave, the plant has a way into your home, working its way through the tiny gaps and potentially causing structural damage or blocking drains. It’s the most invasive plant in the UK and very persistent indeed.

What to do about it?

Whatever you do, don’t ignore it. Japanese knotweed grows rapidly and if it infects your neighbours’ gardens and properties you could be liable for damages. So if you see it in your garden, deal it with properly and quickly.

You need to focus on stopping the plant spreading and getting rid of it. Believe it or not the Environment Agency takes this problem so seriously it has produced a knotweed code of practice to guide those involved in the disposal of the plant through the specific measures that should be undertaken.

It’s targeted towards firms that are involved in the disposal of the plant, but if you have Japanese knotweed on your land it is still essential reading, as it will give you an idea of what you should expect any professionals you employ to be doing.

Key things to be aware of are:

• If you are having the weed fully excavated and disposed of, any contractor you employ needs to be registered with the Environment Agency as a waste carrier. The agency’s website also allows you to search for contractors in your area on its Waste Directory.

• You can also treat the knotweed more slowly with a combination of herbicide treatment and careful excavation if you have no urgent need to get rid of it. But this will take at least three years and you will still have to dispose of the soil in line with the code of practice mentioned above. Plus you should still get a qualified person to carry out the treatment and if you live near a river or stream, you need permission from the Environment Agency before using any chemicals.

• You can burn the waste from Japanese knotweed but you should inform your Local Authority and pay heed to best practice guidelines.

• Soil containing burnt remains of Japanese knotweed may also be buried on the site where it was produced, but very specific guidelines need to be adhered to. Plus you need to inform the Environment Agency a week in advance if burying the waste from your knotweed.

As you can see, there are a lot of hoops to jump through to get rid of this plant properly and it’s little wonder many people pay a contractor to ensure the job is done properly.

But what should you do if you notice this plant and you are about to sell your home? Do you need to go through all of these measures first, or can you sell up with the knotweed in your garden?

Or can you take a risk and just cut it down the day before the viewings and the survey and hope for the best? No!

Be upfront

To be blunt, if you are trying to sell your home and you discover Japanese knotweed in your garden, it is likely to cause you problems. Some buyers won’t touch a house if they know this plant is in the garden, or even neighbouring gardens. And even those that are willing to deal with it may find their mortgage lender will not offer them a loan once they learn of it, because of its potential to cause damage.

But it’s not all bad news. According to the Council of Mortgage Lenders many lenders will now consider lending on a property with Japanese knotweed (and they expect their surveyor to spot it during the valuation). They usually consider applications on a case-by-case basis and look for evidence of an initial treatment, with a commitment to an ongoing treatment programme.

Another reason not to contemplate hiding the presence of Japanese knotweed in your garden is that the Property Information Form used during the property sale transaction has recently been updated to specifically ask a question about it.

However, if you lie on this form you are leaving yourself open to a misrepresentation claim from your buyer, since the documents form part of the pre-contract enquiries and are legally binding.

Japanese knotweed can be a major problem for homeowners but it can also be dealt with if caught early and treated effectively by an experienced contractor. If you have the weed in your garden, tackle it head on because, one thing is certain, it won’t go away without a fight!

Japanese Knotweed Recipes
last modified September 05, 2008

After harvesting this thug, try some of these delicious recipes.

Recipes Utilizing Japanese Knotweed (Polygonum cuspidatum)

Applesauce-Knotweed Cake

For this recipe, you’ll need to harvest Japanese Knotweed stalks at the “wild rhubarb” stage, which typically shows up around the end of April in the Boston area.

Look for stalks about 18-24 inches long, select the fattest stalks you can (at least 3/4 inch in diameter – they’re easier to peel that way), cut at ground level, lop off the top cluster of leaves and bring the stalks home.

Once you’ve got them home, peel the very outer layer (which is stringy) off of each stalk;

Japanese Knotweed stalks are hollow, though, so don’t peel too deeply or all you’ll have left is the hole.

You can eat the peeled stalks raw if you want (their tart, juicy, crunchy texture and flavor is somewhat like that of a Granny Smith apple), or just chop them up for use in the recipe below or just about any other recipe calling for rhubarb.

Ingredients

• 3 eggs
• 1 1/4 cups granulated sugar
• 1/4 teaspoon salt
• 2 cups all-purpose flour
• 1 teaspoon baking soda
• 2 teaspoons cinnamon
• 1/4 teaspoon allspice
• 1/4 teaspoon nutmeg
• 1 cup plain applesauce
• 4 firmly-packed cups peeled Japanese Knotweed stalk pieces

(chop or knead the peeled stalks into small pieces <1” long).

1/2 cup chopped walnuts

• powdered sugar Preheat oven to 350ºF. Grease a 13” by 9” baking pan.

Beat eggs, sugar, salt and vanilla in a large mixing bowl until blended.

In the meantime, mix the flour, baking soda and spices together in a separate bowl.

Add the flour mixture to the mixing bowl, then add the applesauce, knotweed pieces and walnuts and mix until blended.

Pour the batter into the greased baking pan and spread evenly.

Bake at 350ºF for one hour, then remove from the oven and cool on a wire drying rack.

Dust the top with powdered sugar.

Serve warm or cold.

Makes 15 good-sized servings.

Any leftovers can be stored in the refrigerator for use in the next few days or frozen for longer storage.

Go Anywhere Knotweed Squares

You’ll need to harvest Japanese Knotweed stalks at the “wild rhubarb” stage for this recipe, which typically shows up around the first week of May in the Boston area.

Look for stalks about 18-24 inches long, select the fattest stalks you can (at least ¾ inch in diameter – they’re easier to peel that way), cut at ground level, lop off the top cluster of leaves and bring the stalks home.

Once you’ve got them home, peel the very outer layer (which is stringy) off of each stalk; Japanese Knotweed stalks are hollow, though, so don’t peel too deeply or all you’ll have left is the hole.

You can eat the peeled stalks raw if you want (their tart, juicy, crunchy texture and flavor is somewhat like that of a Granny Smith apple), or just chop them up for use in the recipe below or just about any other recipe calling for rhubarb.

Ingredients For bottom crust:

• 1 cup flour

• 1/3 cup confectioners sugar

• 1/3 cup butter (cold) For filling:

• 2 eggs, lightly beaten

• 1 cup sugar

• 1/4 cup flour

• 1 teaspoon vanilla extract

• 1 teaspoon ground cinnamon

• 1/2 teaspoon allspice

• 1/2 teaspoon grated nutmeg

• 3 firmly-packed cups peeled Japanese Knotweed stalk pieces (chop or knead the peeled stalks into small pieces <1” long) Preheat oven to 350ºF.

Grease an 11” by 7” by 2” baking pan.

Put crust ingredients into a food processor and pulverize until mixture resembles coarse crumbs.

Press into the bottom of the baking pan and bake at 350ºF for 12 minutes.

To make the filling,

place all the ingredients except the Knotweed into a bowl and mix together; then stir in the Knotweed pieces.

Pour filling mixture over the warm crust and spread evenly.

Bake at 350ºF for 35-40 minutes or until a toothpick stuck into it comes out clean.

Cool on a wire rack.

Cut into brownie-sized pieces and serve warm.

Any leftovers can be stored in the refrigerator for use in the next few days or frozen for longer storage.

Russ Cohen’s Sour Cream Knotweed Crumb Cake

You’ll need to harvest Japanese Knotweed stalks at the “wild rhubarb” stage for this recipe, which typically shows up around the first week of May in the Boston area.

Look for stalks about 18-24 inches long, select the fattest stalks you can (at least ¾ inch in diameter – they’re easier to peel that way), cut at ground level, lop off the top cluster of leaves and bring the stalks home.

Once you’ve got them home, peel the very outer layer (which is stringy) off of each stalk; Japanese Knotweed stalks are hollow, though, so don’t peel too deeply or all you’ll have left is the hole.

You can eat the peeled stalks raw if you want (their tart, juicy, crunchy texture and flavor is somewhat like that of a Granny Smith apple), or just chop them up for use in the recipe below or just about any other recipe calling for rhubarb.

Ingredients For cake:

• 1 1/2 cups granulated sugar

• 3/4 cup butter, softened

• 3 eggs

• 1 1/2 teaspoons vanilla extract

• 2 1/2 cups all-purpose flour

• 2 teaspoons baking powder

• 1 teaspoon baking soda

• 3/4 teaspoon salt

• 1 cup dairy sour cream

• 5 firmly-packed cups peeled Japanese Knotweed stalk pieces (chop or knead the peeled stalks into small pieces <1” long), tossed with 1/2 cup flour,

1 teaspoon cinnamon,

1/4 teaspoon nutmeg and

1/4 teaspoon allspice in a bowl

For topping:

• 1/2 firmly-packed cup brown sugar

• 1/4 cup all-purpose flour

• 1 teaspoon cinnamon

• 1/4 teaspoon nutmeg

• 1/4 teaspoon allspice

• 1/4 cup cold butter, cut up into small pieces Preheat oven to 350ºF.

Grease a 13” by 9” baking pan.

Cake:

Beat sugar and butter in a in a large bowl on medium speed until blended.

Add eggs and vanilla and beat until creamy.

Mix flour, baking powder, baking soda and salt in a bowl,

then add to the creamed mixture alternatively with the sour cream, mixing well.

Stir in the floured/spiced Knotweed pieces and mix well, then pour the cake batter into the baking pan and spread evenly.

Topping:

Place brown sugar, flour and spices into a food processor and pulse until well-blended;

then add the cold butter pieces and pulse until the entire topping mixture is uniformly crumbly.

Sprinkle the topping evenly over the batter.

Bake at 350ºF for 50-60 minutes or until a wooden toothpick inserted into the center of the cake comes out clean.

Cool on a wire rack; serve warm.

Makes 15 good-sized servings.

Any leftovers can be stored in the refrigerator for use in the next few days or frozen for longer storage.

More info about Russ Cohen’s schedule of public foraging programs: http://users.rcn.com/eatwild/sched.htm More info about Russ’ foraging book, Wild Plants I Have Known…and Eaten: http://users.rcn.com/eatwild/press_release.htm More info about Russ Cohen: http://users.rcn.com/eatwild/bio.htm

Japanese Knotweed Recipe - Knotweed Summer Rolls

Since Japanese knotweed (Polygonum cuspidatum) is so common and highly invasive here in southern New England, it is easy to find in quantity in the early spring.

It is best picked as a tart, toothsome shoot before it gets much bigger than 8" tall.

As it grows, it get tough and stringy and more difficult to incorporate into a recipe.

We have made quite a few sweet recipes with knotweed, like dessert bars, jelly and tapioca.

Here is a savory idea made with raw, sliced knotweed shoots to eat as part of an early spring, edible weed dinner.

We added some other spring edibles as well, all of which are optional or have similar common substitutes.

Any Thai style sweet-sour-spicy dipping sauce is great on the side, and most of the more exotic ingredients are available at an Asian grocery store.

To dip and soften the rice paper wrappers, I use a large pie plate filled with warm water.

It is a good idea to have extra wrappers, since they may rip. Depending on how full you make the wrappers, there will be 6-8 rolls.

Japanese Knotweed Summer Rolls makes 6-8 rolls

6-10 8" Vietnamese rice paper wrappers
3 oz. bean thread noodle cakes
1 c. thinly sliced Japanese knotweed shoot stems
1/2 c. chickweed greens, or parsley and cilantro leaves
3 Tbsp dandelion flower petals
2 Tbsp chopped ramps leaves, or chopped scallions
4 Tbsp shredded carrots

Thai dipping sauce

1. Soak the bean thread noodles in hot water for 10 minutes, until they soften. Rinse and drain well.
2. In a bowl, add the chopped knotweed, chickweed greens, dandelion petals, ramps, and carrots to the bean thread noodles. Toss well.
3. Soften the rice paper wrappers in warm water for about 15 seconds until they are pliable. Place on a smooth surface.
4. Take about 1/2 cup of the noodle filling and place it in the center of the top third of the wrapper. Fold over the top of the wrapper to cover the filling, then fold in the two sided toward the center. Now roll the filled wrapper towards the bottom, enclosing the filling completely. This may take some practice!
5. Chill the summer rolls for 15 minutes, and serve with a spicy-sweet Thai dipping sauce.

Japanese Knotweed Recipe - Knotweed Dessert Bars

We put his recipe up last year, but it really is good and the knotweed is at the optimum height right now. This should be made ideally with the thickest, but shortest stalks you can find so they will be fleshy without any woodiness.

Japanese Knotweed Dessert Bars makes a 11" x 7" pan

Crust:

1 c. flour
1 c. confectioners sugar
6 T cold butter

Filling:
2 large eggs, beaten
2/3 c. white sugar
1/4 c. flour
1 tsp. vanilla
1 tsp. ground cinnamon
1/2 tsp. grated fresh nutmeg
3 c. chopped knotweed stalks, leaves removed

1. Heat the oven to 350°F. Grease the 11" x 7" baking pan.

2. In a food processor, pulse the crust ingredients together to resemble coarse crumbs. Press the crumbs into the bottom of the pan evenly. Bake the crust for 12 minutes.

3. For the filling, combine the eggs, sugar, flour, vanilla, and spices with a whisk. Stir in the chopped knotweed pieces and coat them evenly. Pour the filling mixture over the warm crust and spread it evenly.
4. Bake 30-40 minutes, until the egg mixture is set and a toothpick inserted in the middle comes out clean. Cool. Cut into 1" squares and serve.

Unbaked Knotweed Bars