Plant Care American Knotweed

American Knotweed

Also known as

Narrow-leaf knotweed, Northern knotweed, Birdweed, Common knotgrass, Pigweed, Prostrate knotweed and Lowgrass


Polygonum aviculare

How to care for American Knotweed


How often to water your American Knotweed

Water needs for American Knotweed
0.5 cups
every 9

American 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 American 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 American Knotweed in your home

Light needs and placement for plant American Knotweed: 1ft from a window
1ft or less from
a window

American Knotweed love being close to bright, sunny windows 😎.

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

American Knotweed does not tolerate low-light 🚫.

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


How to fertilize American Knotweed

Nutrient, fertilizer, and repotting needs for American 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 American Knotweed after it doubles in size or once a year—whichever comes first.

Water Needs
Sunlight Needs
Growth Pattern
Growing Outdoors

Care Summary for American Knotweed

American Knotweed

American 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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