|PRIMULA species - Primrose|
Primulaceae; native to North temperate Zones.
Germination: Hardy types are best sown indoors after 3-4 weeks of cold-moist stratification. Sow at 55-65° and expect germination in 21-40 days. They can also be sown outdoors in late fall or early spring with germination occurring in the late spring. Greenhouse types are best sown indoors at 55-65° with germination occurring in 20-25 days. Greenhouse types include P. x kewensis, P. malacoides, and P. sinensis. They should be sown in the summer for flower display indoors in the winter and spring. All types, except for P. sinensis, require light to germinate.
Growth: Site the hardy types in part shade in a slightly acid to alkaline, rich, cool soil that is heavily watered, but still well-drained. They grow best in climates with cool summers. In warm-summered climates, mulch to keep the roots cool. Site the greenhouse types in filtered sunlight, provide 50-60° nights and high humidity, and keep the soil evenly moist.
Appearance and Use: The primroses are grown for a multitude of uses: from borders to bedding and edging, in rock gardens, for naturalizing, and as a greenhouse pot plant. P. auricula has fragrant flowers in colors of yellow, purple, rose, cream, or brown. It is hardy from Zone 3 to 7. P. x kewensis has stacked clusters of 3/4 inch, fragrant, yellow flowers. P. malacoides is hardy outdoors from Zones 8 to 10. It has clusters of 1/2 inch flowers in colors of rose, red, lavender, purple, or white. P. obconica produces red, pink, purple, lilac, or blue flowers. It is hardy in Zone 10. P. x polyantha has 1-2 inch flowers in colors of orange, blue, white, apricot, pink, rose, red, or yellow. It is hardy from Zones 3 to 8. P. sinensis is hardy outdoors in Zone 8. It has flowers that come in colors of red, orange, pink, rose, purple, or blue. P. vulgaris has 21/2 inch clusters of flowers. Flower colors are yellow, purple, blue, red, or white—all with a yellow eye. It is hardy from Zones 5 to 8.
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"Digging up a mature clump of perennials, separating it into segments with new stems and roots and discarding the old core is an effective way to keep plants vigorous, free-flowering and disease-free," Adrian Higgins, The Washington Post Garden Book