HARDINESS: Zones 5 to 8
PREFERRED SOIL pH: Slightly acid
PREFERRED SOIL TYPE: Fertile, moist
PREFERRED LIGHT: Partial shade
ATTRIBUTES: Petite plants with showy, colorful flowers; for damp sites, pots
SEASON OF INTEREST: Spring
FAVORITES: Polyanthus primroses, P. denticulate, P. japonica 'Postford White', cowslips
QUIRKS Often goes dormant in midsummer
GOOD NEIGHBORS: Deciduous trees, spring bulbs, rhododendron
WHERE IT GROWS BEST: Shaded, damp, humus-rich, acidic soil
POTENTIAL PROBLEMS: Cold-winter injury; root rot in wet soil during mild winters
RENEWING: Lives to 5 years; divide PLANTS every 3-4 years
CRITTER RESISTANCE: Occasionally slugs and snails
SOURCE: Bedding plants, division
DIMENSIONS: 4-24 in (10.2-61 cm) tall, 6 in (15.2 cm) wide
Primroses in the Landscape When planted in the right spot, primroses are easy to grow. Not every garden, however, can offer their preferred conditions. These old-fashioned beauties need a climate that is neither too hot nor too cold, partial shade, and a humus-rich, acidic, moist soil. If that doesn't sound like your garden, primroses are best used as niche plants for growing alongside shaded water features or enjoying in containers or window boxes as a sign of spring. They can also be grown as annuals.
Primroses are petite, ranging in height from 8-24 in (20.3-61 cm) when in bloom. Before and after flowering, a low-lying basal rosette of crinkled leaves is the only evidence of their presence. Because of their small size, place primroses where they can be appreciated up close.
The genus Primula includes hundreds of species, but if you want care-free primroses, it is enough to know only a few names. Polyanthus primroses are a large, popular group of easily grown hybrids with blooms ranging from bright white to dark purple. Japanese primrose (P. japonica) has a terrific thirst, but as long as moisture is abundant, varieties like 'Postford White' are hardy and dependable. Because of its globe-shaped clusters of fragrant lilac-colored blossoms, drumstick primrose (P. dmtiaikta) is worth coddling in containers. If you want a primrose for the shade garden, try cowslips (P. veris), which settle in easily to form colonies studded with small yellow flowers in spring.
If you're just getting started with primroses, begin by setting out purchased plants first thing in spring. Prepare the site the previous fall if possible, because plants are eager to bloom soon after the soil becomes workable in spring. Dig in peat moss or another acidic form of organic matter, and make sure the site is convenient to water. In areas where winters are mild, provide primroses with good soil drainage, because waterlogged roots are susceptible to fatal root rot in winter.
Expect the plants to flower for several weeks and then persist as green rosettes until about midsummer. At that point they may seemingly melt away or go dormant, or they may hold a few of their leaves if they are
protected from sun by nearby plants or the tree canopy.
Although primroses can be started from seed, they are slow to grow. The easiest way to obtain more plants is through division. Simply dig an established plant in spring and use a small knife to separate the leaf rosettes. Replant each one individually, along with a piece of root, in a container filled with a potting mix composed of soil and peat moss. Set the plantlets at the same depth at which the mother plant grew. Starting the divisions in containers improves survival, as you can give them closer attention, then shift them to the garden after they have developed a mass of new roots.
Primrose leaves and flower petals can be tattered by night-feeding slugs and snails. Set out saucers of beer to attract and drown them, or collect and dispose of them at twilight.