Over 500 species of primrose (Primula) exist in the world, mostly in Europe and Asia. England has traditionally been known for its primroses, and common varieties, such as the hybrid polyanthus primrose (Primula x polyantha), have originated there. North American breeders have gotten into the primrose act as well, and there are several easy-to-grow varieties for the gardener to try.
The English cowslip (Primula veris) is the first item on The American Primrose Society's Starter List of Primulas compiled by Duane Buell. Traditionally a nodding yellow primrose, according to Buell, the cowslip can come in red, orange and rust, and is slightly fragrant. The basal leaves are deep green and the flower stems are 10 inches high. The plant likes afternoon shade and a moist, but well-drained, soil. Plants bloom in spring.
The true English primrose (Primula vulgaris) is a native yellow species, according to David Buell, and is found in the United Kingdom and parts of Europe. Single flowers appear on stems to 8 inches. It prefers light shade and organically rich, but well-drained, soil. American nurseries sell hybrids in other colors, but yellow is the true original. Plants bloom in spring.
The polyanthus primrose (Primula x polyantha) is a hybrid cross between the cowslip (Primula veris) and the English primrose (Primula vulgaris) bred 300 years ago. Since then, the polyanthus primrose has been hybridized further and comes in many colors. J.Jump recommends planting these if you've never tried primroses before. The plants flower in spring, and flowers are about a foot high.
Juliana primroses (Primula x juliana) are hybrids that stay dwarf and flowers may only be 2 inches high, according to J. Jump. David Buell says they have a lot of color and are a great addition for the border. He recommends varieties such as "Wanda" and "Jay Jay." Plants bloom in early spring.
The drumstick primrose (Primula denticulata) features a large sphere of flowers atop a fleshy stem. Leaves at the base may or not appear in conjunction with the flowers. David Buell calls these primroses "unusual." Stems are 12 inches high. The plant likes moisture and shade, and blooms in early spring.