Persicaria affinis Superba

The Persicaria affinis Superba is adorned from summer to autumn with numerous pale pink and carmine pink bicoloured flower spikes. This perennial forms a vigorous, dense carpet of foliage, with shiny green leaves that taper towards the petiole and have finely toothed edges, taking on beautiful brown hues in autumn. Easy to grow in any well-drained but moist soil, in full sun or partial shade.

The Persicaria affinis Superba, also known as Polygonum affine Superbum or Himalayan Knotweed, belongs to the Polygonaceae family. As partially indicated by its name, it is native to the entire Himalayan range from Afghanistan in the west to northern Myanmar in the east and is very hardy.

The plant is very vigorous and compact; wider than tall, it grows to 20 cm (8in) in height and 60 cm (24in) in width, forming a tight carpet. The oblong leaves (reversed lance shape, wider at the top and ending in a blunt tip) are shiny green and take on beautiful brown shades in autumn, turning coppery in winter. The laminae reach 5 to 10 cm (2 to 4in) in length. The small conical flowers cluster in cylindrical spikes measuring 5 to 8 cm (2 to 3in). Their colour evolves with the seasons: from pale pink, they darken until they become carmine red at the end of flowering, giving them an original bicoloured appearance.

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

This rhizomatous, creeping plant forms a vibrant ground cover that can be used as a border along pathways. Its broad soil preferences allow it to adapt to rockeries and the edges of water features. It can also be planted in pots. Its long flowering period from July to October gives it summer and autumn interest. It can be profitably combined with plants that have remarkable characteristics during this season, such as the magnificent purple berries of Callicarpa bodinieri Profusion, bronze or ochre-coloured grasses like Molinia, or one or more varieties of autumn-flowering Camellias. The Persicaria affinis Superba is stoloniferous, self-seeds easily, and naturalises with alarming ease. Therefore, be cautious, as it can become invasive in non-freezing climates.