Overview
Clematis patens is a deciduous, woody climbing vine in the Ranunculaceae family, growing 6–10 feet (1.8–3 m) tall by twining leaf petioles around supports. It is one of the most important parent species of the large-flowered clematis hybrids — many popular cultivars including 'Nelly Moser', 'The President', and 'Lasurstern' derive significant parentage from C. patens. Leaves are pinnately compound with 3–5 ovate leaflets 2–4 inches (5–10 cm) long. Flowers are large, flat to slightly cupped, 4–6 inches (10–15 cm) across with 6–8 broad, overlapping tepals (sepals) in white, blue, lavender, or violet. A central boss of cream to yellow stamens provides contrast. Flowers are borne singly on short peduncles from the previous year's wood (old wood) — this is a critical cultivation point, as pruning at the wrong time removes the flowering wood. In the wild, the species occurs in mountain scrub and forest margins in Japan, China, and Korea. Bloom occurs in late spring (May–June) on stems produced the previous year, with occasional rebloom in late summer on current-year growth. The species is the genetic source of the large flower size and early bloom timing found in Group 2 (light-prune) clematis hybrids. Susceptible to clematis wilt (Phoma clematidina) and powdery mildew.
Native Range
Clematis patens is native to Japan (Honshu, Shikoku, Kyushu), eastern China (Hubei, Sichuan, Zhejiang), and Korea. It occurs in mountain forests, forest margins, and scrubland at elevations of 300–6,500 feet (100–2,000 m).Suggested Uses
Trained on trellises, fences, pergolas, and obelisks, or grown through established shrubs and small trees. The large flowers create a focal point at eye level when grown on a 6-foot (1.8 m) trellis. Combine with a Group 3 (hard-prune) clematis on the same support for successive bloom from spring through autumn. Effective in large containers (minimum 10 gallons / 38 L) with a support structure.How to Identify
Appearance
Size & Dimensions
Height6' - 10'
Width/Spread3' - 5'
Reaches mature size in approximately 3 years
Bloom Information
Primary bloom occurs in May–June on the previous year's stems. Flowers open over a 3–4 week period. A lighter secondary bloom may occur in August–September on current-season growth. Individual flowers last 7–10 days. Pollinated by bees and other insects.Detailed Descriptions
Flower Description
White, blue, lavender, or violet with cream stamensFoliage Description
Medium greenGrowing Conditions
Sun Requirements
Requires 4-8 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
Care & Maintenance
Care Guide
Plant in full sun to partial shade with the root zone shaded or mulched. Site in fertile, moist but well-drained soil with a pH of 6.5–7.5. Plant with the top of the rootball 2–3 inches (5–8 cm) below soil level to encourage basal bud regeneration in case of wilt. Space 4–6 feet (1.2–1.8 m) from other climbers. Provide a sturdy support — trellis, obelisk, or established shrub. Water regularly — 1 inch (2.5 cm) per week during the growing season. Feed with a balanced fertiliser in spring as buds break and again after the first flush of bloom. Mulch the root zone with 2–3 inches (5–8 cm) of organic material to keep roots cool.Pruning
Pruning Group 2 (light prune). In late winter (February), remove dead and weak stems only. Do NOT hard-prune — the primary spring bloom occurs on the previous year's wood. After the first flush of flowers in June, lightly trim flowered shoots back to a strong pair of buds to encourage a second flush on new growth. If clematis wilt strikes, cut all affected stems to ground level — the plant may regenerate from the deeply planted base.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
late spring
Maintenance Level
moderateContainer Growing
✓ Suitable for container growing
Minimum container size: 10 gallons