Large leaves make dramatic counterpoints to small-leaved plants; their lush textures and tropical-like dimensions bring an exoticness to temperate landscapes. Unfortunately, there is a paucity of perennials with big, bold foliage for northern gardens—giant rhubarb (Gunnera manicata) is too tender, butterbur (Petasites japonicus) is too weedy, and ligularias (Ligularia spp.) are too often finicky. On the other hand, rodgersias (Rodgersia spp.) are well-mannered, cold-hardy alternatives that fill the niche beautifully.
Rodgersias are notable for their large, dark green leaves. In spring, emerging leaf color varies among rodgersias and may be wholly burgundy to bronze or simply tinged with those colors. In most cases, the leaves turn fully green although some degree of bronze coloration may remain throughout the summer.
For optimum health and growth, rodgersias do best in consistently moist soils—no standing water though—in sunny or shady gardens that are sheltered from desiccating winds. Cultural missteps are the usual cause of poor performance and unsightly displays. Plants that receive inadequate moisture become tatty and unkempt as the summer goes on. This problem is exacerbated by high temperatures and direct sunlight that can also scorch the foliage. Rodgersias are fairly untroubled by diseases, although slugs and snails can be pests.
For a full evaluation study of rodgersias from the Chicago Botanic Garden, visit http://bit.ly/rodgersias.
Richard Hawke is the plant evaluation manager and associate scientist at the Chicago Botanic Garden.
