27 December 2012

Walking down the primrose path


The English Primroses made famous by Shakespeare grew wild in shady meadows. Since then, primroses have faded from cottage gardens but new hybrids are helping them make a come-back.

There are over 400 Primula species that bloom in early spring on stalks above rosettes of crinkly leaves.  Common primrose, Primula vulgaris has single flowers on 6-inch stems. They are related to cowslips (Primula veris) and oxlips (Primula elatior).


P. sieboldii Mac Gradens
Primula sieboldii goes dormant in the summer though if they are mulched and watered the rhizomes will spread to send up even more the following spring. The flowers are pink, white, purple or mauve on 12-inch stems.

Polyanthus primroses are easy to grow hybrids. They need to be divided every few years as they spread. They have large clusters of red, purple, yellow, white, pink or blue flowers on stems that can grow to a foot tall. Plant them with spring flowering bulbs and cut them back by half after they finish blooming.

Drumstick primrose (Primula denticulata) will self-sow and spread in the right conditions. It blooms early with lavender and purple flowers on 2-inch stems.

Primroses are cold hardy in zones 4 to 9 and cannot thrive in warmer zones.  In half-shade locations where they are watered, primroses will become perennials. They can also be used as houseplants and as annuals outside in containers. They like soil amended with composted leaves, manure and other composts.

All primroses are insect, disease, rabbit and deer resistant, though not deer proof. Heat stress can bring spider mites. If they are planted too close together they can get leaf spot. In the summer, mulch with chopped leaves or other organic material to protect them from the heat.

P. obcondia Thompson Morgan Seeds
Plants will be available in garden centers in early spring;  the seeds are started in January. German Primrose, Primula obcondia, seeds produce plants with large, fragrant, single flowers on 10-inch stems. Flower colors include lavender, red, pink and white.

Plant seeds in potting soil and barely cover them with vermiculite. Put the pots outside on the north side of a building where they are exposed to weather but protect them from direct sun, wind and strong rainfall. During drought periods, water from the bottom and let them drain.

When the seedlings have two sets of leaves, move them to flats with their seed starting soil. You can keep them in pots over the spring and summer and transplant them into a permanent garden spot in the fall.

For spring plants, start the seeds in January but keep them inside a greenhouse or under lights when they emerge.

When planting in the spring or re-planting divisions in the fall, keep the crown above the soil level and do not press them into the ground.

Pink Ice Skagit Gardens
The Double Primula vulgaris Bellarina series is a collection of new hybrids grown from cuttings. The flowers look like roses and come in several colors including: Pink Ice, Nectarine, Cream, Yellow and Cobalt Blue.  They are hardy in USDA zones 5 to 11 and bloom a long time because they do not produce seed.

Midnight Garden
Companion plants include other part-shade-loving plants such as Hostas, Virginia bluebells (Mertensia virginica), woodland phlox (Phlox divaricata) and ferns.

To grow Primroses as houseplants, keep them on a bright windowsill but out of direct sunlight. Water them regularly and let them drain after watering. Keep them away from heat sources such as furnace vents. Fertilize with liquid fertilizer mixed at half strength when flowering.

Photos of primroses are at The American Primrose Society (www.americanprimrosesociety.org) and www.primulaworld.com.

 Primrose plants are available from Bluestone Perennials (www.bluestoneperennials.com) and seeds are available from www.swallowtailgardenseeds.com  and www.thompson-morgan.com. Primula obconica Libra Blue seeds are available from www.hardyplants.com.

1 comment:

Amanda Plante said...

Great information. I've had limited success with primrose in the past, and that experience has hindered me from trying them again. Girded with information from your blog, I'm going to give it another stab. Thanks and have a happy new year!