A Japanese import some 130 years ago, Primula japonica is a classic garden plant of easy culture. A very typical candelabra Primula it has striking whorled tiers of rich colours standing majestically above striking mid-green luxuriant foliage.
Primula japonica ‘Millers Crimson’ produces whorls of scarlet-red blooms and makes a wonderful display in shady, damp spots and woodlands. It is very tolerant of the wettest heavy soils, in fact it will thrive under such conditions. Flowering time is May and height at its peak is 60cm (2 feet). It forms a large clump which is easily divided and will self seed given damp dappled conditions.
It will grow in full light in the bog garden but given some dappled shade will grow in most situations where the soil remains moist at all times. For the best impact, plant them in large drifts.

Sowing: Sow seeds in late spring/early summer or late summer/autumn.
Primula seeds need a period of cold and damp to enable them to germinate. Sow on the surface of seed compost, cover with grit and keep in a shaded cold-frame or cool glasshouse.
Sow seed 2.5cm (1in) apart in trays or cells containing seed compost. Sow the seeds on the surface of the compost, (Do not cover – they need light to germinate) and place in a light position at a regular temperature of around 16°C (60°F) Germination should take place between 21 and 40 days.

Primula seeds can also be sown during warmer times of the year, but it would be necessary to artificially simulate “winter” using the following method of “stratification”:
Place the seeds between two pieces of damp filter paper or folded kitchen roll then put into a polythene bag and place this into the fridge at 4°C (39°F) which is the temperature that most fridges are set at. Inspect the seeds after two weeks and remove as the seedlings appear, returning the ungerminated seeds to the fridge.
Although most seeds should germinate in 4 to 5 weeks, germination can be erratic, it is not unknown for seeds still to be germinating up to two years after sowing. Remove the seedlings and place the pot in a shaded corner of the garden….just in case!
When seedlings have their first pair of true leaves and are large enough to handle, transplant into 7.5cm (3in) pots containing peaty compost. Grow on then gradually acclimatise to outdoor conditions for 10 to 15 days before planting out. Plant them in a humus-rich, moisture retentive soil and in partial shade. Tolerates full sun if soil remains moist at all times.

Cultivation:
The important factor is that the roots should not dry out, so incorporate plenty of organic matter when you plant, mulch well in autumn and spring and water regularly if they are in the open.
Cut back after flowering. Once established, they benefit from being lifted and divided every two years in early spring.
Allow this Primula to seed down and you will get a colourful array of seedlings to carpet the moist area.

Plant Uses:
Shade and Woodland Gardens. Bog, ponds and streams. Wildlife and Pollinators.

Origin:
Primulas are one of the most popular species of plants which are seen in gardens. There are at least 425 species with over 300 of them found in Asia. 33 more are found in Europe and 20 found in North America.
Botanists have subdivided this large genus into thirty-seven sections. The vast majority can be found in the high, damp meadows of the Himalayas and western China, where 334 species are native. They are also familiar spring wildflowers of the European country-side, where they have been appreciated for centuries.

Nomenclature:
The genus Primrose is ultimately derived from Old French primerose or medieval Latin prima rosa, meaning “first rose”.( Latin primus – meaning ‘first’ and Rosa for Rose). Primroses flowers in early spring, one of the earliest spring flowers in much of Europe.
The species name japonica simply means that it originates from Japan.
Primula japonica is a ‘proliferae’ type of primula, the word derives from ‘proliferate’, meaning to increase in number rapidly, which refers to the whorls of flowers. They are also commonly called Candelabra section primulas.
Candelabra primulas take their name from the fact that the flowers on the plants in this group are arranged in whorls set at intervals up an otherwise bare stem. The general effect is like a candelabrum.
Primrose and Polyanthus are a diverse group of the Primulaceae, the Primula family. There are societies dedicated to single species that are centuries old and many other societies which have their roots in the Victorian era where several species where highly desirable for collections and collectors.

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Germination Instructions

Sow indoors or under glass in spring, sow into a cold frame in autumn. Indoors, surface sow onto moist well-drained seed compost. Just cover with grit. Place some where cool, ideal temp. 15-22°C. Germination takes 21-40 days. Germination can be erratic taking much longer. If germination does not occur cold stratify. Move to 4°C, a fridge is ideal, for 4-6 weeks then return to warmth for germination. When seedlings are large enough to handle transplant to 8cm pots and grow on. Acclimatise and plant out after danger of frost has passed. Can be sown into a cold frame in autumn where winter cold should offer ideal conditions for germination to occur in spring as the weather warms.

Growing Instructions

Prefers a damp soil with plenty or added organic matter in partial sun. Requires little attention. Roots must not dry out.

Cultivation Instructions

Cut back after flowering. Will self-seed. Propagate by seed or division. Lift and divide every two years in spring.

When to Sow

MarM AprA MayM JunJ JulJ AugA SepS OctO NovN DecD JanJ FebF
  • Sow Under Cover/Plant Indoors
  • Flowers/Harvest

Primula Species, Japanese Cowslip, Japanese Primrose, Queen of Primroses

Category:

Alpines and Rock Gardens

Perennials

Water Requirements:

Requires consistently moist soil; do not let dry out between waterings

Sun Exposure:

Light Shade

Foliage:

Deciduous

Foliage Color:

Unknown – Tell us

Height:

18-24 in. (45-60 cm)

Spacing:

15-18 in. (38-45 cm)

Hardiness:

USDA Zone 3a: to -39.9 °C (-40 °F)

USDA Zone 3b: to -37.2 °C (-35 °F)

USDA Zone 4a: to -34.4 °C (-30 °F)

USDA Zone 4b: to -31.6 °C (-25 °F)

USDA Zone 5a: to -28.8 °C (-20 °F)

USDA Zone 5b: to -26.1 °C (-15 °F)

USDA Zone 6a: to -23.3 °C (-10 °F)

USDA Zone 6b: to -20.5 °C (-5 °F)

USDA Zone 7a: to -17.7 °C (0 °F)

USDA Zone 7b: to -14.9 °C (5 °F)

USDA Zone 8a: to -12.2 °C (10 °F)

USDA Zone 8b: to -9.4 °C (15 °F)

USDA Zone 9a: to -6.6 °C (20 °F)

USDA Zone 9b: to -3.8 °C (25 °F)

Where to Grow:

Grow outdoors year-round in hardiness zone

Can be grown as an annual

Danger:

Seed is poisonous if ingested

Handling plant may cause skin irritation or allergic reaction

Bloom Color:

Pink

Red

Medium Purple

White/Near White

Bloom Characteristics:

Unknown – Tell us

Bloom Size:

Unknown – Tell us

Bloom Time:

Late Spring/Early Summer

Other details:

Unknown – Tell us

Soil pH requirements:

5.6 to 6.0 (acidic)

6.1 to 6.5 (mildly acidic)

6.6 to 7.5 (neutral)

Patent Information:

Non-patented

Propagation Methods:

By dividing the rootball

From seed; winter sow in vented containers, coldframe or unheated greenhouse

From seed; sow indoors before last frost

Seed Collecting:

Allow pods to dry on plant; break open to collect seeds

Regional

This plant has been said to grow in the following regions:

Juneau, Alaska

Grayslake, Illinois

Mount Prospect, Illinois

Winnetka, Illinois

South China, Maine

Littleton, Massachusetts

Wellesley Hills, Massachusetts

Minneapolis, Minnesota

Saint Paul, Minnesota

Brooklyn, New York

Hilton, New York

Ithaca, New York

Hendersonville, North Carolina

Glouster, Ohio

Molalla, Oregon

Sherwood, Oregon

Allentown, Pennsylvania

Wilkes Barre, Pennsylvania

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Japanese Primrose

Japanese primrose is a member of the garden world and one of over 400 species of primroses. Most primroses revel in an English climate calling for cool temperatures and plenty of rainfall and are at a loss in the often short spring and variable summers found over much of the United States. The species listed below performs well in this country. The genus name is a diminutive of the Latin primus, “first,” alluding to the early flowering of certain European species.

: The basal foliage is a rosette with dark green, heart-shaped leaves with a scalloped edge. The plant bears tight bunches of 2-inch wide, pink or purple deckle-edged flowers on 12-inch stems. Each has a white “eye.” Ease of care: Easy.

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: Japanese primroses require partial shade and a good, moist soil. Unlike other primroses, the leaves disappear and plants become dormant in the summer and are spared the rigors of drought and heat.

Propagating Japanese primrose: By division or by seed.

: Primroses are unexcelled for the woodland garden or for planting among spring wildflowers in a shady spot of the garden — even without bloom the foliage is very attractive. They make excellent cut flowers. Dormant plants may be potted up in late winter and forced into bloom at normal room temperatures.

elated varieties: The Barnhaven hybrids come in colors of frost-white, rose-red, lilac, China blue, and pink. Blossom shape varies from perfectly round to fringed to a snowflake form. Geisha Girl is shocking pink. Mikado is magenta. Ice Princess is pale blue — darker at edges. Snowflake and Late Snow are pure white.

: Primula sieboldii

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