Growing Primula in South-Central Alaska

By Mary Jo Burns, Master Gardener

The Primula family is large and varied with over 430 species found throughout cooler regions of the northern hemisphere. With some basic knowledge we can grow many species and hybrids here in our everyday Alaskan gardens.

To make this large group of plants easier to study, they have been grouped according to species that resemble each other, often hybridize with each other and usually need the same kind of care. These groups are called “sections”.

General Growing Culture

Ample water and a good, humus rich, well-draining soil
Partial or light shade: many will grow in full sun as long as ample water is provided
Sharp sand, grit or gravel added to the soil enhance drainage
Periodic addition of compost, leaf mulch and/or aged steer manure

Winter Survival

Many primula are somewhat “promiscuous” within their sections, and open pollination in your garden can produce new hybrids, surprising you with new colors and flowers.
Primula can be grown by seed. Many primula will self seed in the garden or seeds may be gathered for planting. Fresh seed, planted as soon as it has ripened has the best germination results.
Primulas are easily propagated by division. Most are vigorous growers and can be divided every two years or so. Division of primula often promotes continuing vigor.
Some primula can be propagated by root cuttings or “offsets” produced on the main root.
Some primulas are rhizomatous and may be propagated by separating out rhizomes.

Sections

Section Auricula

P. auricula

Very hardy, alpine plants with thick leathery leaves, various colored fragrant flower clusters on strong stems, often with a mealy powdery coating or farina* on many or all parts of the plant. In the wild, they grow in very well drained, gravelly or rocky soils with adequate humus. In cultivation they will grow in full sun to light shade with well-drained, semi-rich mineral soil. Ample water is necessary in full sun. Sharp sand, rock chips and gravel can be worked into garden soil around the roots of auriculas to provide the sharper drainage they need.

Auriculas bloom in the early spring, around the end of May and into June. P. auricula will grow in most garden soil with excellent drainage. They seem to be especially happy when planted in close proximity to rocks, perhaps because this provides for a cool root run which helps to sustain them in full sun. Auricula are easily grown from seed or offsets.

* Paste, meal, farina or farinose: a white or yellow powdery substance on many primroses. It is a protein enzyme or flavonoid made in a plant gland. It is not known what purpose this substance serves. It can be washed off by rain or watering directly onto the plant.

P. allionii and hybrids

Smaller plants; grow them drier in the fall and winter; Good for rock gardens or a cold/alpine greenhouse; propagate by division, cuttings or seeds.

P. marginata and marginata hybrids.

Usually tooth-edged leaves on small sized plants often coated in white or golden meal or farina, flowering in early May with flowers of blue, lavender, bright pinks and white. Good for rock gardens; propagate from seed or cuttings.

P. pubescens

Smaller sized auricula -- hybrids of P. auricula and P. hirsuta; exceptionally hardy even in persistent rain; long lived and do well in rockeries. Propagate by division, rooting offsets and seed.

There are also reported successes in growing other primula in the Auricula section, such as P. clusiana, P. wulfeniana, P. pedemontana, and P. villosa.

Section Denticulata

P. denticulata

Called the “Drumstick” primrose because of its large ball of blossoms on tall sturdy stems; blooms early in the spring before the leaves have fully matured in colors of purple, magenta, lavender and white. As the season progresses the stems elongate and the leaves get very large – so give it some room. In the wild, it grows in moist meadows and slopes. In cultivation, provide ample water, good drainage and a humus rich soil.

In winter, it dies back to a large fleshy resting bud that is easily heaved out by the frosts of winter. If found in time, they can be pushed them back into the soil or replanted. To prevent this damage, divide the larger clumps about every two years, which gives them more space and better drainage. The large resting bud is susceptible to rotting in the spring if winter mulch is not removed as early as is safe since the soil may remain too wet. Denticulata frequently self-seeds; may be propagated by root cuttings, but plant division is easier and you will have larger plants more quickly.

Section Cortusoides

P. sieboldii

Grows in moist, grassy woodlands; blooms in pink, lavender, magenta and white with stripes, ruffles and a multitude of shapes. This primula grows well in a shaded, moist border without any special soils. P. sieboldii will often go dormant in the warm summer or after blooming, dying back to small underground rhizomes at or just below the surface of the soil. Be sure to mark where your plants are or you run the risk of digging them up. It spreads by rhizomes just under the soil surface and it’s easy to divide these to propagate. It may also be grown from seed, but it isn’t always a very heavy seed producer. Seeds are often available through various seed exchange programs.

Section Sikkemensis

P. florindae, P. alpicola, P. waltonii, P. sikkemensis and various hybrids

Native to the Himalayan moist meadow, these are tall, fragrant and come in yellow, gold, cream, orange, apricot, copper, lavender-violet, and shades of red from dusky reds to wine reds.

These plants easily hybridize so they grow into mixes of all shades and will often self sow. The flowers are large clusters of hanging bells and flourish in wet areas. The more moisture they have, the larger and lusher they grow. Place near ponds and creeks or even leaky faucets. Water, water, water and rich well-draining soil is the key to these primula. Breaking dormancy later in spring than most primula, they usually bloom in early July and continue right up until frost. Happy plants form large clumps up to 2’ wide and flower stems can reach 3-4’ on some species. Propagate by division or seed although they often do not come true from seed because of their hybridizing.

Section Primula

P. veris

The “Cowslip” is the most widespread of all wild Primula. Veris flowers in June producing clusters of flowers on a single stem. Often naturalized in grass, they are easy to grow in regular good garden soil with adequate moisture. Colors include the species deep yellow and the “sunset shades” of reds which come from crosses with red or pink forms of other primula within this section. Propagate by seed or division.

P. elatior

The “Oxlip” blooms early in pale to light yellow and may be found widely distributed across Asia and Europe. All elatior make splendid rock garden plants and will also grow well in good regular garden soil with adequate moisture. P. elatior ssp. Meyeri flowers in shades of lavender and pinks. Propagate by division; grows easily from seed frequently self sowing.

P. vulgaris

(Also referred to as P. acaulis) Woodland plant that loves cool, humus rich soils. This is the primula that comes to mind when one hears “English Primrose”. It does well in partly shaded flowerbeds and forms nice clumps. The species flowers are usually a bright yellow. P. vulgaris hybridizes easily with other primula in its section. Vulgaris hybrids include many of the popular doubles such as ‘Lilian Harvey and ‘Dawn Ansell’ and the P. Belarina series. P. vulgaris ssp sibthorpii blooms with pale lilac-pink flowers. Propagated primarily by division; they are not heavy seed producers; and double flowers rarely produce seed in the open garden.

P. x polyanthus

This is not a true species, but a group of primula with very complex and generally unrecorded hybrid histories. For the most part they are a mixture of P. vulgaris, P. elatior, and P. veris.

This is also the popular polyanthus often found in the supermarkets in early spring in an astonishing array of colors. Not necessarily bred for garden vigor, if planted out and mulched for winter, many will often survive our winters.

P. juliae

P. juliae and its hybrids are among the easiest to grow; they like part shade, humus rich soils and moisture. They bloom early and profusely. Some “juliana hybrids”, now correctly named Primula x Pruhoniciana, may bloom again after the initial spring bloom. P. juliae and hybrids are stoloniferous and will build clumps that are easy to divide. Locally grown favorites include “Kinlough Beauty”, “Wanda”, “Dorothy”, “City of Juneau” and “Pinwheel” which are often shared among local gardeners and found at local plant sales. Propagated primarily by division, but seed may be available through various seed exchanges and commercial sources.

Section Proliferae

P. chungensis, P. japonica, P. beesiana, P. bulleyana, P. bullesiana, P. burmanica, and P. cockburniana

Also known as Candelabra primroses, in natural settings they typically grow in mountain meadows and thin woods, wet from melting snow in spring and monsoons in summer. In fall they grow in slightly dryer conditions and in winter are covered in snow.

They grow well in a soil rich with organic matter and good drainage and tend to want more water than some, but they can also handle more or deeper shade.

Leaves die back in fall and they resume growth late in spring, so keep note of where they’re planted. A bit promiscuous, species in this section will cross with others in their neighborhood and often produce an array of colors. Propagate by seed and division. Fresh seed germinates easily and they will self sow.

Section Aleurita

P. laurentiana, P. scotica, P. stricta, P. mistassinica, P. farinosa, P. frondosa, P. halleri, P. scandivavica, and P. borealis.

These are some of the smaller primula, many with farina or meal, often called “bird’s eye” primroses. In natural settings primula of this section are often found in soils that may contain chalk, clay, limestone and even fossil shells in spring fed, open ground and also in drier grasslands.

In cultivation, they seem to do well in a humus rich and slightly sandy soil, with good drainage and ample water. Some shade is beneficial with more water needed if in direct sun. If ample water can be provided many of these will do well in alpine and rock gardens and there have been some successes reported with trough gardens. Many are short-lived, but if they are happy, they will readily self-sow. Propagated primarily by seed.

Primula Sources

Plants may be found seasonally at many area greenhouses, nurseries and garden supply centers, and at local garden groups’ plant sales in the spring. Don’t forget that making friends with primula growing gardeners may lead to sharing plants!

Online plant listings of primula include:

Fritz Creek Gardens: alaskahardy.com

In The Garden Nursery: Inthegardennursery.com

‘Outside’ nurseries online specializing in primula; many will ship to Alaska.

Seeds are also available through several gardening society seed exchange programs and various commercial sources.

American Primrose Society

americanprimrosesociety.org

APS website features links to primula related websites, primula sources, etc. Members receive a quarterly publication and access to yearly seed exchange.

Primula Study Group

An informal primula interest group organized by Mary Jo Burns in response to a growing interest in primroses by Anchorage area gardeners. The group meets periodically to learn more about primroses by sharing primula growing experiences.

Contacts: Mary Jo Burns (907) 248-2827 or Jane Baldwin (907) 562-5451.

Primula References

Primula by John Richards; 1993, rev. edition. This is a very good basic reference for primula.

Alaskan Primrose Primer by Sally Arant (former co-owner of In The Garden Nursery)

Primula World: primulaworld.com - This is a website with many incredible primula pictures of almost all varieties of primula.

There are many other primula references available, some in print, some out of print but obtainable.

Happy Primula Gardening!

Jane Baldwin at ABG

Jane Baldwin at the Alaska Botanical Garden Fair, 2009, at the Primula Booth

Photos on the site by: Jane Baldwin, Mary Jo Burns, and Gina Docherty