What hardiness zones is Primula kisoana suitable for?

Primula kisoana is suitable for USDA hardiness zones 4, 5, 6, 7, 8.

What are the sun requirements for Primula kisoana?

Primula kisoana requires Part Shade.

How much water does Primula kisoana need?

Primula kisoana has Medium water needs.

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Perennials

Primula kisoana

Kisan primrose

PrimulaceaeAsia

At a Glance

TypePerennial

HabitSpreading

FoliageDeciduous

Height4–8 inches (10–20 cm)

Width6–12 inches (15–30 cm)

Maturity3 years

Growing Zones

USDA Hardiness Zones

4 - 8

Zone 4

Zone 5

Zone 6

Zone 7

Zone 8

These zones indicate the coldest temperatures this plant can typically survive.

Frost Tolerancehardy

Key Features

Attracts Pollinators

Container Friendly

Maintenancelow

Overview

Primula kisoana, commonly called Kiso primrose, is a charming, slowly spreading herbaceous perennial in the family Primulaceae, endemic to montane deciduous forest margins, rocky slopes, and moist woodland clearings on Honshu and Shikoku islands of Japan, where it grows in humus-rich, well-drained soils in partial shade. It is one of the most distinctive primulas in cultivation, immediately recognizable by its large, softly hairy, palmately lobed, maple-like leaves — quite unlike the typical primrose leaf form — densely covered in soft white glandular hairs on both surfaces, giving the whole plant a distinctly fuzzy texture. In early spring, stout hairy scapes 4–8 inches (10–20 cm) tall bear clusters of two to six deep rose-pink to rose-mauve flowers with a lighter eye, each approximately 0.75–1 inch (2–2.5 cm) across. The plant spreads slowly by stolons to form colonies of modest size over time. It is an excellent, long-lived, and low-maintenance primula for the cool, moist shade conditions of Pacific Northwest woodland gardens, where it thrives in conditions similar to its montane Japanese habitat.

Native Range

Endemic to Honshu and Shikoku islands of Japan, growing in montane deciduous forest margins, rocky woodland clearings, and moist, partially shaded slopes at low to mid elevations (approximately 1,300–5,600 feet / 400–1,700 m), in humus-rich, well-drained, slightly acidic to neutral soils. Not native to North America.

Suggested Uses

Kiso primrose is a refined and distinctive primula for the Pacific Northwest cool woodland garden, offering the combined attractions of early rose-pink flowers and unusually textured, maple-like hairy foliage through the growing season. Best placed at the front of a shaded border or woodland path edge where the fuzzy maple-like leaves can be appreciated at close range. Combines naturally with other Japanese woodland plants — Epimedium, Disporum, Trillium, and delicate-leaved ferns. The slow-spreading stoloniferous habit gradually forms a modest colony that is never invasive.

How to Identify

Kiso primrose is identified by its distinctive, large, softly and densely hairy, palmately lobed, maple-like basal leaves 2–5 inches (5–13 cm) across — quite different from the typical wrinkled oval leaves of most primulas. Both leaf surfaces and the flowering scapes are covered in conspicuous soft white glandular hairs giving the whole plant a fuzzy or woolly appearance. In early spring, clusters of two to six deep rose-pink to rose-mauve, five-petaled flowers with a slightly paler eye are borne on stout hairy scapes 4–8 inches (10–20 cm) tall. The combination of maple-like fuzzy leaves and rose-pink spring flowers is diagnostic.

Appearance

Size & Dimensions

Height4" - 8"

Width/Spread6" - 1'

Reaches mature size in approximately 3 years

Colors

Flower Colors

pink

Foliage Colors

green

Fall Foliage Colors

yellow

Bloom Information

Bloom Period

~4 weeks

Spring

Kiso primrose blooms in early spring, typically March through April in Pacific Northwest woodland gardens. Clusters of two to six deep rose-pink to rose-mauve flowers, each approximately 0.75–1 inch (2–2.5 cm) across, are borne on stout hairy scapes 4–8 inches (10–20 cm) tall. Flowering lasts three to four weeks. After flowering the hairy, maple-like foliage remains attractive through summer, dying back in autumn. The combination of early flowering and distinctive textured foliage makes this a dual-season plant.

Detailed Descriptions

Flower Description

Deep rose-pink to rose-mauve; five-petaled with lighter eye; in clusters of 2–6 on stout hairy scapes

Foliage Description

Large, palmately lobed, maple-like, mid-green; densely covered in soft white glandular hairs on both surfaces — distinctly fuzzy texture

Growing Conditions

Sun Requirements

Partial Shade

Full Shade

Tolerates up to 4 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 7.0(Neutral)

357912

Soil Types

loampeat

Drainage

well drained

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

2–3 years

Care & Maintenance

Care Guide

Plant in partial shade in moist, humus-rich, well-drained, slightly acidic to neutral soil. Kiso primrose thrives in the cool, moist conditions of Pacific Northwest woodland gardens — avoid hot, dry, or sunny exposures. Incorporate generous leaf mold at planting. Keep consistently moist through the growing season; the plant tolerates some summer dryness once established but performs best with consistent moisture. Mulch lightly with leaf mold to retain moisture and protect the stoloniferous runners. Allow the colony to spread naturally by stolons — do not divide frequently.

Pruning

No routine pruning is required. Remove dead or damaged leaves as needed. Allow the foliage to die back naturally in late autumn. Remove any leaves heavily affected by slugs or disease. The plant is generally clean and low-maintenance.

Pruning Schedule

fall

Maintenance Level

low

Container Growing

✓ Suitable for container growing

Minimum container size: 3 gallons

⚠️ Toxicity Warning

Non-toxic