Download Growing Primula in South-Central Alaska

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
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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
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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 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 more lush they grow. Place
near ponds and creeks or even leaky faucets. Water, water, water and rich
well-draining soil are 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 the Alaska Botanical Garden Fair, 2009, at the Primula Booth
Photos on the site by: Jane Baldwin, Mary Jo Burns, and Gina Docherty
Copyright © AMGA - contact [email protected] for information or questions.