Sunset zones: 1-6, 17.
USDA zones: 5-8.
Height: 12-24 inches (30-60 cm).
Width: 12 inches (30 cm).
June to July.
Spikes of red calyces with blue-violet flowers opening from the bottom and working up. Many times each spike will have over 100 flowers densely packed on the stem.
Deciduous, lance-shaped, hairy leaves. Leaves are late in appearing in May, later than most primroses.
Moist, humus rich, well-drained, neutral to acidic soil.
Side dress with compost or top dress with leaf mold and a complete organic fertilizer in spring.
Sow seed in late winter to early spring 68°F (20°C). Do not cover seed.
Rainy Side Notes
When in bloom, Primula vialii is easy to distinguish from other primroses. Its stout stalk is crowded with hundreds of tiny flowers of red calyces and blue-violet corollas. Flowering from June into July, the flowers are tightly packed on the stem. The blossom has a bottle brush appearance, similar to the red-hot poker plant (Kniphofia), although smaller. This primrose has distinctive flowers, unlike any other in the genus. It's rare to find this plant in its native haunts, as it comes close, if not already, to being an endangered species.
Pere Delavay originally discovered the species. There was some confusion to the name Delavay gave the plant. Later when George Forrest found them, he concluded they were a new discovery. He named the primrose P. littoniana. introducing them in 1906. It took some time for the name to be straightened out and given back its original name, P. vialii.
Easy to start from seed, I sow in late winter and keep in the greenhouse until spring, when the plants are moved into the garden after a hardening period. The seed remains viable for two years. They reliably bloom their second year, growing best under the protection of shrubs, such as rhododendrons. Since P. vialii's foliage is dormant for seven months of the year, the best way to plant them is as a colony under and around evergreen ferns or other small plants. When they come into bloom they are spectacular. The short-lived perennials thrive in moist, humus rich, well-drained soil with lots of leaf mold. In these conditions the plants will sometimes live longer. Since they are late to leaf out in spring, mark their positions well.
Photographed in author's garden.