Plant Care Japanese knotweed

Japanese knotweed

About Japanese knotweed

Japanese knotweed is a super rare houseplant 🌿 that is a fun challenge to grow and needs regular watering to thrive. They do best in long-lasting, direct light ☀️ and should be less than 1 foot from a window.

Japanese knotweed likes soil that is well draining. You may want to supplement with a gentle, organic fertilizer throughout the peak growing season.

Japanese knotweed belongs to the reynoutria genus, and is native to Eastern Asia.


Reynoutria japonica

Also known as

Asian knotweed

How to care for Japanese knotweed


How often to water your Japanese knotweed

Water needs for Japanese knotweed
0.5 cups
every 9

Japanese knotweed needs 0.5 cups of water every 9 when it doesn’t get direct sunlight and is potted in a 5" pot.

Use our water calculator to personalize watering recommendations to your environment or download Greg for more advanced recommendations for all of your plants.

Calculate water needs of Japanese knotweed

Water 0.5 cups every

Does your plant get direct sunlight?

Select the pot size


Check the growing potential in your area

A plant's growing potential is determined from its location, the time of year, and current local weather.

Select a city to check sunlight intensity

Finding light for Japanese knotweed in your home

Light needs and placement for plant Japanese knotweed: 1ft from a window
1ft or less from
a window

Japanese knotweed love being close to bright, sunny windows 😎.

Place it less than 1ft from a south-facing window to maximize the potential for growth.

Japanese knotweed does not tolerate low-light 🚫.

Select your region to see how the current weather in your area affects the placement of Japanese knotweed in your home 🏡.


How to fertilize Japanese knotweed

Nutrient, fertilizer, and repotting needs for Japanese knotweed: repot after 2X growth

Most potting soils come with ample nutrients which plants use to produce new growth.

By the time your plant has depleted the nutrients in its soil it’s likely grown enough to need a larger pot anyway.

To replenish this plant's nutrients, repot your Japanese knotweed after it doubles in size or once a year—whichever comes first.

Difficulty Level

Japanese knotweed can be challenging to care for, according to some plant parents. Check out the reviews down below to learn from their experiences!

Water Needs
Sunlight Needs

Care Summary for Japanese knotweed

Japanese knotweed

Japanese knotweed

Greg recommends:


0.5 cups every 9 days


< 1ft from a window


Repot after 2x growth

Based on the 4” pot your plant is in, and that it doesn’t get direct sunlight.

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