Persicaria Species, Big Seeded Smartweed, Pennsylvania Smartweed, Pink Knotweed, Pinkweed

Persicariapensylvanica

Genus
Persicaria (per-sih-KAR-ee-uh)
Species
pensylvanica (pen-sill-VAN-ee-ka)
Synonym
Persicaria pensylvanica var. laevigata
Polygonum pensylvanicum
Sun Exposure
Full Sun
Sun to Partial Shade
Light Shade
Foliage
Smooth
Textured
Height
36-48 in. (90-120 cm)
Spacing
18-24 in. (45-60 cm)
Hardiness
Not Applicable
Danger
Handling plant may cause skin irritation or allergic reaction
Bloom Color
Pale Pink
Pink
Rose/Mauve
Bloom Time
Late Spring/Early Summer
Mid Summer
Late Summer/Early Fall
Other Details
Category
Annuals
Herbs
Water Requirements
Foliage Color
Where to Grow
Bloom Characteristics
This plant is attractive to bees, butterflies and/or birds
Bloom Size
Other details
May be a noxious weed or invasive
Soil pH requirements
4.5 or below (very acidic)
4.6 to 5.0 (highly acidic)
5.1 to 5.5 (strongly acidic)
5.6 to 6.0 (acidic)
6.1 to 6.5 (mildly acidic)
6.6 to 7.5 (neutral)
7.6 to 7.8 (mildly alkaline)
7.9 to 8.5 (alkaline)
Patent Information
Non-patented
Propagation Methods
From seed; direct sow outdoors in fall
From seed; winter sow in vented containers, coldframe or unheated greenhouse
From seed; stratify if sowing indoors
Self-sows freely; deadhead if you do not want volunteer seedlings next season
Seed Collecting
Bag seedheads to capture ripening seed
Allow seedheads to dry on plants; remove and collect seeds
Properly cleaned, seed can be successfully stored
Regional

This plant is said to grow outdoors in the following regions:

Prescott Valley, Arizona

Deer, Arkansas

New Milford, Connecticut

Demorest, Georgia

Leavenworth, Kansas

Benton, Kentucky

Melbourne, Kentucky

Brookeville, Maryland

Cumberland, Maryland

Vicksburg, Mississippi

Ogdensburg, New York

Orient, Ohio

San Antonio, Texas

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Gardener's Notes:

1
positive
2
neutrals
3
negatives
Sort By:
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P
Valparaiso, IN | July 2013 | positive

Polygonum pensylvanicum is native to the U.S. and I can't get enough of the beautiful flowers, so it's a positive in my book.
...Read More

K
Highland Heights, KY (Zone 6a) | July 2011 | negative

I thought these were pretty when they showed up in one area, so I let them stay. Big mistake--now I am pulling them up everywhere! If you...Read More

N
Vicksburg, MS (Zone 8a) | February 2009 | neutral

I like to find this weed when it's flowering in local fields. When the flowers are at the pink stage I clip a big bunch to use in dried f...Read More

C
Brookeville, MD (Zone 7a) | May 2005 | negative

Me no likey.

This plant is a pest in recently disturbed earth, which means any new gardens or freshly dug up gardens.
...Read More

J
J
Palmyra, IL (Zone 5b) | January 2005 | neutral

This native annual plant is 1-4' tall, branching occasionally. It is more or less erect, often bending toward the light in partially sha...Read More

M
M
Benton, KY (Zone 7a) | January 2005 | negative

An invasive weed that has the ability to reproduce itself from even the tiniest bit of stem. It grows in cultivated fields, gardens and d...Read More

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