These easy-care spreaders give a profusion of bright blooms
Relatives of persicarias include some nasty weeds, such as the infamous Japanese knotweed.
But this large group of mostly herbaceous plants from Europe and Asia also includes really
useful garden plants, tolerant of moist and heavy soils, which bring attractive foliage and a
profusion of flowers to the garden during summer and autumn.
The most eye-catching can be mixed in herbaceous borders with day lilies, phlox and late-flowering asters, while the toughest, such as ‘Superba’, make ideal ground cover. They have
suffered from name changes and are often listed as polygonums.
Rich, moist soil will help you get the best from persicarias. Most will bloom best if they get sun
for at least half the day, though a few, especially P. campanulata, survive in tough, dry areas. A few are invasive but the most popular form neat clumps that can be divided in autumn or spring when dormant. They rarely need deadheading or staking, and are free from pests and diseases, although mildew can attack plants grown in dry soils.