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aquatic

Water Smartweed

Polygonum amphibium

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Water Smartweed (Polygonum amphibium) at Vandermeer Nursery

Water Smartweed foliage

Water Smartweed foliage

(Photo courtesy of NetPS Plant Finder)

Plant Height:  12 inches

Flower Height:  18 inches

Spread:  12 inches

Sunlight:  full sun  partial shade 

Hardiness Zone:  5b

Other Names:  syn. Persicaria amphibia, Water Knotweed

Description:

Narrow spikes of pink flowers rise above clumps of green arrowhead shaped foliage in mid to late summer; prefers constantly moist soil and will grow in water

Ornamental Features

Water Smartweed has masses of beautiful spikes of pink flowers rising above the foliage from mid to late summer, which are most effective when planted in groupings. The flowers are excellent for cutting. Its attractive pointy leaves remain green in colour throughout the season. The fruit is not ornamentally significant.

Landscape Attributes

Water Smartweed is an herbaceous perennial with a low habit of growth, spreading atop the surface of the water. Its medium texture blends into the garden, but can always be balanced by a couple of finer or coarser plants for an effective composition.

This plant will require occasional maintenance and upkeep, and is best cleaned up in early spring before it resumes active growth for the season. It has no significant negative characteristics.

Water Smartweed is ideally suited for growing in a pond, water garden or patio water container, and is recommended for the following landscape applications;

  • General Garden Use
  • Water Gardens
  • Naturalizing And Woodland Gardens
  • Container Planting
  • Bog Gardens

Planting & Growing

Water Smartweed will grow to be about 12 inches tall at maturity extending to 18 inches tall with the flowers, with a spread of 12 inches. Its foliage tends to remain dense right to the water, not requiring facer plants in front. It grows at a medium rate, and under ideal conditions can be expected to live for approximately 10 years.

This plant does best in full sun to partial shade. As an aquatic plant, it requires a suitable water garden environment and will benefit from special planting and ongoing care practices; consult one of our in-store experts for further details and instructions. It is not particular as to soil type or pH. It is highly tolerant of urban pollution and will even thrive in inner city environments. This species is native to parts of North America. It can be propagated by division.

Water Smartweed is a fine choice for the water garden, but it is also a good selection for planting in outdoor pots and containers. Because of its spreading habit of growth, it is ideally suited for use as a 'spiller' in the 'spiller-thriller-filler' container combination; plant it near the edges where it can spill gracefully over the pot. Note that when grown in outdoor pots and containers, aquatic plants like this one will require a special growing environment that meets their requirement for consistent moisture.

 
 
Hardiness Zone Plant Height Minimum Sunlight
Characteristics
Garden  Naturalizing  Container  Bog  Water 
Applications
Flowers  Foliage Color 
Ornamental Features
Vandermeer Nursery is open year-round and we are constantly updating our inventory. Please note that not all plants may be in stock at all times. Please call our store for current availability and pricing for any plant listed.