GBG Note No. 8

Primula as a Bedding Plant

by Dr. Meriam G. Karlsson

Primulas (primroses) have become popular in many states as bedding plants for early spring plantings. Shading from direct sunshine during primula greenhouse production is recommended. The primary reason for reducing natural irradiance is to improve temperature control as primula does not grow well at temperatures above 68°F. Under conditions with moderate ambient temperatures, primula has been shown to withstand and thrive under high light conditions. The reasonable summer temperatures of Alaska may allow primulas to develop satisfactory even in sunny locations.

The primulas planted here are of the two species Primula vulgaris (or Primula acaulis, English primrose) and Primula malacoides (Fairy primrose). The plants with white or pink flowers in an umbel are Primula malacoides. Primula vulgaris is native to the Mediterranean countries and Primula malacoides to China. Available cultivars of Primula vulgaris and Primula malacoides have been developed for good greenhouse performance and should be treated as annuals when planted outdoors.

There are three cultivars of Primula vulgaris planted here. The front and back rows are 'Danova Winered' (Dæhnfeldt Inc.), the plants around the P. malacoides are of the cultivars 'Saga' (Goldsmith Seeds Inc.) in blue, scarlet or white flower color and 'Dania Lemon Yellow' (Dæhnfeldt Inc.). The cultivar of Primula malacoides is 'Prima' (Dæhnfeldt Inc.) in carmine rose, light rose or white flower color. Seed was sown in the greenhouse on December 20, 1991 and the seedlings were transplanted on January 20, 1992 into four-inch pots. The plants were grown in a greenhouse maintained at 60°F and planted in the garden on June 9, 1992. To compare the effects of light intensity, plants are grown in full sun and in the shade house further to the east in the garden.

GBG Notes