Bistorta Affinis

Bistorta affinis: Unveiling the Beauty of the Himalayan Bistort

Bistorta affinis, also known as Polygonum affine, Fleece Flower, Lesser Knotweed, East Indian Knotweed, or Himalayan Bistort, is a captivating perennial plant native to the Tibet and Himalayan regions. Belonging to the genus Bistorta and the Polygonaceae family, this exquisite plant forms sprawling mats that gracefully cascade over rocks and steep slopes in the central Himalayas. With fresh green leaves emerging in spring and delightful flower spikes developing in late summer, Bistorta affinis showcases numerous small pink or red flowers that transform into rich hues of red and chestnut-brown after the first frosts.

Plant Description and Blooming

Bistorta affinis, also known by its synonyms Polygonum affine and Persicaria affinis, is a creeping, densely tufted, mat-forming perennial that reaches a height of 25 cm (10 in) and spreads to about 60 cm (24 in) in width. Its narrow elliptic leaves feature a striking white underside due to a waxy coating. Most of the leaves are concentrated at the base, measuring 3–8 cm in length, tapering into a short stalk.

The leaf margins are either entire or finely toothed, while the mid-vein stands out prominently. Atop short erect stems, cylindrical spikes adorned with many pale pink or rose-red flowers appear from midsummer to autumn. These flower spikes, about 5–7.5 cm (2–3 in) long, exhibit densely crowded flowers, with the stamens slightly protruding. Several flowering stems, ranging from 5 to 25 cm tall, emerge with very few smaller leaves. Even after the flowers have faded, they often persist on the plant throughout the winter.

Bistorta Affinis
Beautiful flowers of Bistorta Affinis

Cultivation and Care of Bistorta affinis:

Bistorta affinis thrives in full sun or partial shade, making it a versatile addition to your garden. This low-maintenance plant reaches a modest height of 25 cm (10 in) and displays enchanting pink flowers from July to September. Propagation can be done through seeds or division, and it generally remains disease-free and pest-free.

Planting: Choose a suitable location with well-drained soil, opting for either full sun or partial shade. The soil should be slightly acidic to neutral. Prior to planting, amend the soil with compost or manure to enhance its fertility. Space the plants approximately 12-18 inches apart.

Watering: While Bistorta affinis is drought-tolerant once established, it appreciates regular watering during its first year after planting. Once the plant has taken root, it only requires watering during dry periods.

Fertilizer: Bistorta affinis does not demand frequent fertilization. A light application of fertilizer in the spring will help stimulate new growth and support its overall vitality.

Pruning: Minimal pruning is necessary for Bistorta affinis. Removing spent flowers, known as deadheading, encourages the plant to produce more blooms. In the autumn, consider cutting back the plant by one-third to promote new growth when spring arrives.

Overwintering: Bistorta affinis is hardy in USDA zones 4-9. For regions with colder climates, providing a layer of mulch around the plants can offer protection against the cold, ensuring their survival and vigor.

Bistorta Affinis
Salmon pink colored flower of Bistorta Affinis
Bistorta Affinis
Bistorta Affinis at Kew Gardens

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