Pinkhead knotweed plants (Polygonum capitatum or Persicaria capitata) are considered excellent low-growing groundcover by some gardeners.They are also called invasive pests by others. Himalayan Knotweed. Dwarf knotweed (Persicaria affinis, syn. long (8 cm), densely packed with tiny, pale pink flowers that deepen to crimson as they mature. If the invasive Persicarias have turned you off to this genus, I’d urge you to look again at Persicaria affinis varieties. Our garden-worthy selections are happiest in semishade with ample moisture. If you read up on pink knotweed information, you’ll find that the plant is banned in England and considered invasive in California. Persicaria Knotweed. Persicaria amplexicaulis, commonly known as mountain fleece or red bistort, is an herbaceous perennial that typically grows in a dense leafy mound to 3-4’ (infrequently to 6’) tall and as wide.It is native to the Himalayas. Blooming for weeks from midsummer into fall, the blossoms are borne above the foliage mat of elliptic to lance-shaped, deep green leaves which turn bronzy-red in the fall. Popular Varieties of Persicaria Grown in the UK. Lady's Thumb Persicaria maculosa Knotweed family (Polygonaceae) Description: This plant is a summer annual that is ½â€“2' tall and more or less erect, although individual plants may sprawl. Poor Persicaria! Spreading plant to 1 feet high, 2 feet or more wide. Click on an acronym to view each weed list, or click here for a composite list of Weeds of the U.S. This plant can be weedy or invasive according to the authoritative sources noted below.This plant may be known by one or more common names in different places, and some are listed above. Certain weedy, invasive members of the genus have given the rest a bad name, and discouraged gardeners from getting to know these versatile performers. Vigorous, Persicaria affinis 'Superba' (Lesser Knotweed) is a mat-forming, semi-evergreen perennial boasting charming spikes, 3 in. Persicaria ‘Dimity’ thrives in USDA Zones 5-9, possibly as low as 3. There are many different cultivars of Persicaria available from medium to dwarf height. The next spring it will burst out of the ground and be in bloom with the iris in late May. Persicaria is commonly known as ‘knotweed’ and some species are garden worthy while others present some problems. Each plant has grown wider rather than taller, with the norm being about 2.5' high by 2' across. From a fist-size division Persicaria polymorpha should give you a blooming plant in the first season. Himalayan native. They get about 18″ tall and 3′ wide, though mine have spread slightly wider with age. Deep green, lance-shaped, finely tooth-edged leaves are mostly basal; they grow 2412 inches long, turn bronze in winter. Some persicarias have been classified as invasive, but so far these have not tried to expand outside of the current planting area. A group of useful woodland plants that handle damp conditions, some species do have a tendency to roam can be an issue. Look for the less invasive species such as Persicaria affinis, Persicaria bistorta and Persicaria amplexicaulis. Zones US, MS, LS; USDA 6-8. Most groundcover plants are a bit to very invasive… and that’s normal, considering that we choose groundcovers specifically for their ability to cover ground. Persicaria polymorpha Common name: Great White Fleece Flower; Giant Fleece Flower. Flower colours range from red to pink and white P. affinis (Himalayan bistort) a compact, low-growing variety with pink or red flowers that last from summer through to autumn. Noteworthy Characteristics. The stems are usually light green, round, and glabrous or slightly pubescent. To roam can be an issue mostly basal ; they grow 2412 long! 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