Polygonum is generally grown as a herbaceous border plant, although the popular P. affine is sometimes planted in the rock garden. This is usually a mistake as the highly invasive species, such as P. affine, can easily overrun the less robust alpines growing nearby. There are just two species which are recommended for the rockery.
VARIETIES: P. vaccinifolium is the common rockery type – height 6 in., spread 3 ft.
Flowering period: September-December. In late autumn the upright spikes of small pinkand the red-tinged of this evergreen are a welcome sight. It is wide spreading but can be easily kept under control if required – use it to cover large rocks or to cascade over retaining walls. If you want something smaller, choose P. tenuicaule – height 4 in., spread 1 ft.
Flowering period: March-April. The white flowers are borne on small upright spikes.
SITE AND SOIL: Any well-drained soil – thrives best in full sun.
PROPAGATION: Divide clumps in autumn or spring. Alternatively plant non-floweringin autumn.