Facts About Primroses

Candelabra Types

• These primroses grow on relatively tall stems, sometimes reaching up to 2 feet. The flowers are borne in clusters. Candelabra types include Bulle's primrose (Primula x bulleesiana), a hybrid variety hardy in U.S. Department of Agriculture plant hardiness zones 4 through 7. Bulle's primrose blooms in early summer and features whorls of small flowers that bloom in tiers on the stems. Japanese primrose (Primula japonica), hardy in USDA zones 4 through 8, features 18 inch stems and red flower clusters in the species. Plant breeders have developed varieties in many colors.

Polyanthus

• Probably the most familiar primroses are the polyanthas (Primula (polyanthus type)), hybrids that are hardy in USDA zones 7 through 9. The plants are small -- from 6 to 9 inches tall --- and bear bright-colored single flowers, often with contrasting yellow centers. Polyanthas can be planted in gardens in spring and overwintered within their hardiness zone, or treated as annuals elsewhere. They are also grown commercially in greenhouse and sold by nurseries and garden centers as inexpensive winter container plants.

Show Varieties

• Some of the most unusual primulas are the show auricula types, which feature centers covered with a layer of white, mealy substance called "farina." These plants are generally grow in greenhouses and are shown in protected exhibition areas or special outdoor "theaters," because rain damages the farina. The petal edges or margins may be shades of gray, pea green or black, or a dramatic black ring may surround the farina-covered center. "Chloe" (Primula "Chloe"), hardy in USDA zones 5 through 8, is an example, with a white center and black petals edged in pale green.

Culture

• Though show primulas are usually grown in greenhouses, most of the plants can be grown outside in partial shade. Primulas are water lovers, and some, like the "North Hill Strain candelabra variety, (Primula bulleesiana "North Hill Strain") can be grown successfully on stream banks or near ponds. The soil for primroses should be rich, very well drained and on the acid side of the pH scale. Amend with grit for alpine varieties. Some primulas, especially the polyanthas, may be relatively short lived.