Solanum - Growing Guide

The species and varieties of solanum which we grow range from the hardy to the not so hardy. The genus includes the potato (Solanum tuberosum), and all species have flowers which have distinct similarities with the flowers of a potato. The species listed here are mainly climbing plants which will, with some initial help and support, climb up walls and fences. S. rantonettii can be grown as a wall or freestanding shrub and is the only tender species currently available.

Solanum like to be grown in full sun in reasonably fertile soil but are happy in dry periods. They will tolerate slightly alkaline soil.

If grown in the greenhouse, up a wall, or on a trellis in a pot they will need regular pruning to keep them under control. This is best attempted in the spring as solanum flower on the new growth.

S. crispum ‘Glasnevin’ is a fast growing, scrambling, or climbing, evergreen variety with deep purple-blue flowers in terminal corymbs. Indoors you may well get flowers in early summer but, outside, it tends to flower from midsummer well on into the autumn. This species originates in Chile and is perfectly hardy. It can grow eventually to 15ft or so.

S. jasminoides (S. laxum) is known as the potato vine or jasmine nightshade. It is also a vigorous, hardy, scrambling evergreen which may only be semi evergreen in colder parts of the country. Its jasmine or potato like flowers appear between July and September, and much earlier if grown under glass. The flowers are fragrant and bluish-white and are followed by spherical black fruit which can look a bit like the fruits of the deadly nightshade which is also a species in the solanum family.

S. jasminoides ‘Album’ is a pure white form.

S. rantonettii’ Royal Robe’ is an especially large-flowered form with fragrant violet-blue flowers with yellow centres that start trumpet shaped and then open out flat in summer and autumn. It originates from Paraguay and Argentina and is really a summer bedding or greenhouse plant of great merit. You can perhaps train it as a wall shrub outdoors in the mildest areas but, at Burncoose, it makes a 3-5ft tall multi-stemmed plant in the conservatory which we cut back nearly to the base each spring.