a Hardy Hibiscus for the North
Common Name: rose of Sharon
Botanical Name: Hibiscus syriacus
Form: upright vase, multi-stemmed
Plant Type: deciduous shrub
Mature Size: 8 to 12 feet x 6 to 10 feet
Origin: China to India
Hardiness Zone: 5 to 8
Foliage: palmate veined with 3 lobes and coarsely serrated margins up to 4 inches long.
Flowers: June to October, circular flared 5 petalled blossoms up to 3 inches wide, single prominent pistil column with many stamens. Pinks, reds, purples and white, often with a colourful eye in the centre.
Fruit: seed pods with small black viable seeds in October.
Exposure: full sun to light shade.
Soil: soil tolerant but prefers moist well-drained soil. Benefits from a layer of mulch. Aborts flower buds if soil is too dry.
Uses: mix borders, hedgerow, naturalize, birds, butterflies, foundation, containers.
Propagation: semi-hardwood cuttings just prior to flowering, seeds (seedlings may not resemble parent plant).
Pruning: late winter before new growth emerges.
Problems: self-seeds, no serious problems, slight susceptibility of Japanese beetles, whiteflies, aphids, rusts, blights.
Rose of Sharon are the hibiscus of the north. This showy shrub is a hardy relative of the more exotic and tropical hibiscus, Hibiscus rosa-sinensis (USDA Zones 9 to 11). Their hollyhock-like flowers last for just a day, however, they blossom for a few months in late summer to frost. Many cultivars are available with colours ranging from reds, blues, purples and whites. A protruding stamen laden pistil is surrounded by 5 petals for single varieties and many more for double varieties. A colourful contrasting ‘eye’ often surrounds the base of the pistil.
Rose of Sharon perform best in full sun in humus rich moist soil surrounded by 3 inches of an organic mulch. Although they like the heat of summer they do not like dry soil and will abort their flower buds if the soil is too dry. On the other hand, yellow foliage often indicates overwatering.
If conditions are satisfactory their seeds will form colonies around the mother plant. However, since the babies will not be identical to the parent plant, you might get some beauties – if you want to grow them on. Winterkill:
Avoid fertilizing after July as new growth is susceptible to frost damage.
In Zones 5 and less, pile 6 inches of a winter mulch over the crown (where stem and roots meet).
To prevent leggy-ness and encourage compact growth, cut back stems back to 2 to 3 buds in late winter to early spring.
Remove spent blossoms after flowering to prevent them from re-seeding in areas where it is a problem.
Birds & Wildlife: Blossoms are frequented by bees, butterflies and other pollinators. Their seeds provide food for many birds.