Common Name: hardy primrose
Type: Herbaceous perennial
Family: Primulaceae
Native Range: Japan
Zone: 4 to 8
Height: 0.50 to 0.75 feet
Spread: 0.50 to 0.75 feet
Bloom Time: April to May
Bloom Description: Pink to rose mauve
Sun: Part shade
Water: Medium
Maintenance: Low
Suggested Use: Ground Cover, Naturalize
Flower: Showy
Attracts: Butterflies
Culture
Best grown in deep, evenly moist, humusy, organically rich, well-drained soils in part shade. Tolerates close to full shade. May tolerate full sun in cool northern summers if soils are kept consistently moist. Plant foliage may depreciate in the heat of hot summer climates. Intolerant of standing water. Protect from excess winter moisture. Spreads in the garden by stoloniferous rhizomes and self-seeding to form colonies. Propagate by division or seed.
Noteworthy Characteristics
Primula kisoana, commonly called hardy primrose, is an herbaceous perennial that is primarily grown for its deep rose to rose mauve flowers which bloom in spring above a mat of thick, wrinkled, orbicular-cordate, basal leaves. Both the foliage and the flowering stems have prominent downy white hairs. It is native to Japan where it was originally collected at Mt. Kiso (hence the specific epithet and the sometimes used common name of Mount Kiso primrose). It is now listed as an endangered species in Japan because its current distribution is limited to shaded alpine to sub-alpine forest areas around Mt. Narukami in the southern part of Gunma Prefecture on Honshu Island. It can no longer be found at Mt. Kiso.
Large velvety green leaves (to 3-6" long) with ruffled to shallowly-lobed margins form clumps of basal foliage (to 6" tall) which typically creep by stoloniferous rhizomes to form attractive foliage mats. Deep rose to rose-mauve flowers with deeply notched petals bloom in spring (April-May) in 2-6 flowered terminal umbels atop stout, leafless, rose-pink flowering stems which are covered with downy white hairs. Flowering stems rise above the foliage to 6-8" tall.
The genus name Primula means "little earliest one" and is the feminine diminutive of the Latin primus.
Problems
No serious insect or disease problems. Slugs, snails, aphids and red spider mites are sometimes seen. Botritis, gray mold, root rot, rust, powdery mildew and leaf spots may occur.
Uses
Bright spring flowers that grow well in part shade locations including border fronts, rock gardens, open woodland gardens, under trees, along paths, along streams/ponds or in boggy areas. May be an effective edger. Also may be grown in pots.