Persicaria affinis Darjeeling Red

Persicaria affinis 'Darjeeling Red' is a lovely semi-evergreen perennial with pale-pink flower spikes that turn garnet when mature. The foliage turns copper in winter.

Persicaria affinis 'Darjeeling Red', also known as Polygonum affine 'Darjeeling Red' or Himalayan Knotweed, belongs to the Polygonaceae family. It is native to the entire Himalayan range from Afghanistan in the west to northern Myanmar in the east.

The plant is vigorous and compact, wider than it is tall, reaching a height of 25cm (10in) and a width of 40cm (16in), forming a very dense carpet. The lanceolate leaves are dark green and glossy. They turn red in autumn and become copper-coloured in winter. The laminae reach an average length of 15cm (6in). The small conical flowers cluster together in cylindrical spikes measuring 5 to 6cm (2in). Their colour changes with the seasons: starting with a pale-pink, they darken until they become deep red garnet at the end of flowering.

It thrives in all types of soil, even the poorest or most unfavourable, as long as they remain moist throughout the year. Due to its mountainous origin, it is very hardy and tolerates negative temperatures down to -15°C (5°F). It prefers full sun or partial shade.

This rhizomatous, creeping plant forms a dense, colourful ground cover that can be used as a border alongside paths. Its wide soil preferences allow it to adapt to rockeries as well as the edges of water features. It can also be planted in pots. Its long flowering period (from June to October) makes it attractive in summer and autumn. It can be combined with plants that have remarkable characteristics during this season, such as Callicarpa bodinieri 'Profusion' with its magnificent purple berries, bronze or ochre-coloured grasses like Molinia, or one or more varieties of autumn Camellia. Persicaria affinis 'Darjeeling Red' spreads by stolons, self-seeds spontaneously, and naturalises with disconcerting ease. Therefore, in non-freezing climates, it can become invasive.