Robust persicaria puts on a colourful show
STILL going in gardens and boosted by the recent spell of warm weather, a number of forms of persicaria offer a good show of colour through the late summer and into autumn for flower beds and rock gardens.
Although the various species of persicaria differ a lot in size -- from over one metre tall to just 10cm -- they are still very recognisable when judged by their foliage and flowers. The foliage is narrowly heart-shaped and pointed, although it varies greatly in size and the flowers are short or long spikes of tiny florets, in shades of pink and red.
Native to the Himalayan region of China, Persicaria campanulata grows to about one metre tall and wide, covered over the top for months with loose spikes of pale pink flowers. It has an airy appearance and makes a great filler for a large garden. It is very robust, loves rich, moist soil and will take some light shade. When frost hits, the stems wither and the plant overwinters as close-set rosettes of green leaves at soil level.
Another vigorous grower, Persicaria amplexicaulis forms a mound of relatively long foliage with slender flower spikes. The flowers are red or pink and there are white forms. One of the most beautiful is 'Firetail', a bright red-crimson colour, the flowers carried in profusion on slender, long, branching stems, giving it a lively airy effect. This is excellent in a border as a filler. 'Inverleith' is a shorter form, about half-height and carries deep red spikes.
Bistort is about 50cm tall, with stubby cigar-shaped flower clusters on slender stems. It loves moist ground and looks well by a stream-edge, or in a bog-garden, where it produces a leafy top that competes well with weeds. The pale pink flowers are produced from early summer to autumn, often in flushes.
Making a broad spreading mat of green leaves, Persicaria affinis carries elegant pink flower spikes well shown above the leaves, flowering from mid-summer well into autumn. Ideal for a rockery or edging a paved area, late in the year the flowers and leaves wither to brown and remain very decorative during the winter. 'Superba' has pink flowers that turn red. 'Dimity' has light pink flowers and its leaves turn red in autumn before withering to brown.
The smallest kind is Persicaria vacciniifolia, a rock garden plant which makes a flat carpet of small leaves. It flowers in late summer and well into autumn producing upright spikes of small pink flowers. These flowers look remarkably like those of heather, similar in shape and colour. It looks great creeping over the low wall of a raised bed or at the base of a wall or kerb.