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Clematis × jackmanii
Late large‑flowered clematis; Pruning Group 3 · George Jackman, 1862, UK
At‑a‑glance
- Group/Class: Late large‑flowered clematis; Pruning Group 3
- Height × spread: 7–10 ft × 3–6 ft (2.1–3.0 m × 0.9–1.8 m)
- Bloom window: July to September
- Color & flower form: Deep violet purple single flowers, 5–7 in (12–18 cm) across
- Fragrance: 0 none
- USDA hardiness: zones 4 to 8
- Breeder / Year / Origin: George Jackman, 1862, UK
- Awards/registration: RHS Award of Garden Merit
- Pet safety: avoid
How it differs
- Blooms on current season wood while many early clematis flower on old wood
- Richer violet purple color than typical pale large‑flowered hybrids
- Moderate height compared with very vigorous ramblers
- Handles colder winters better than many large‑flowered forms
Strengths
- Profuse mid to late summer bloom on new growth
- Tolerates full sun with shaded roots
- Reliable in zones 4 to 8 when sited and pruned well
Care in one minute
Site: full sun to part shade; shade the crown and roots with mulch or low perennials; good air flow.
Soil: fertile, moisture‑retentive but well‑drained; neutral to slightly alkaline pH.
Water: keep evenly moist through summer; do not let the root zone bake.
Feeding: apply a low‑nitrogen, slow‑release fertilizer in spring; repeat light feeds during growth.
Pruning: Group 3; cut back to strong buds 8–12 in above ground in late winter.
Overwintering: mulch the root zone in cold climates to buffer freeze–thaw.
Watch‑outs
- Susceptible to clematis wilt in some gardens
- Needs support; stems can break if untied in wind
- Root zone should not dry out in summer heat
Best uses (tags)
Provenance note
Raised from crosses among *C. lanuginosa* and *C. viticella* by George Jackman in England; introduction year reported as 1862 to 1863.
References
- Missouri Botanical Garden – Plant Finder: Clematis ‘Jackmanii’
- RHS – Clematis: pruning groups
- NC State Extension – Clematis × jackmanii
