Clematis 'Jackmanii' Clematis x jackmanii
Clematis 'Jackmanii' (Clematis x jackmanii) is a deciduous perennial flowering plant in the Ranunculaceae family, native to Garden hybrid raised in England in 1858 (C. lanuginosa x C. viticella). It grows 2.5–4 m (8.2–13 ft) tall and 1–1.5 m (3.3–4.9 ft) wide, wants full sun and moderate water, and is hardy to about -34 °C (-29 °F). Space plants about 1 m (3.3 ft) apart.
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Clematis 'Jackmanii' at a glance
| Type | Perennial flowering plant, deciduous |
|---|---|
| Family | Ranunculaceae |
| Mature height | 2.5–4 m (8.2–13 ft) |
| Mature spread | 1–1.5 m (3.3–4.9 ft) |
| Spacing | 1 m (3.3 ft) centre to centre |
| Sun | Full sun, at least 5 h of direct sun a day |
| Water | Moderate; drought tolerance low, waterlogging tolerance none |
| Soil pH | 6.5–7.5 |
| Cold hardiness | About -34 °C (-29 °F) once established (roughly USDA zone 4) |
| Heat stress | Likely above about 30 °C (86 °F) |
| Flowering | from about July for 11–16 weeks (northern hemisphere; later in cold climates, earlier in warm ones) |
| Wind tolerance | Low |
| Pollinator value | Low |
| Edible | Not grown as food |
| Native to | Garden hybrid raised in England in 1858 (C. lanuginosa x C. viticella) |
| Common in gardens of | 🇬🇧 United Kingdom, 🇺🇸 United States, 🇩🇪 Germany, 🇯🇵 Japan |
Is Clematis 'Jackmanii' toxic?
- People: moderately toxic
- Cats: mildly toxic
- Dogs: mildly toxic
- Parts: sap, all parts
Contains ranunculin, which releases the irritant protoanemonin; sap blisters skin and mouth, and ingestion causes drooling and vomiting.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Clematis 'Jackmanii'
No well-documented helpful pairing. Group it with plants that like full sun and moderate water.
Questions about Clematis 'Jackmanii'
- How far apart should I plant Clematis 'Jackmanii'?
- About 1 m (3.3 ft) apart, centre to centre. A mature plant spreads 1–1.5 m (3.3–4.9 ft).
- Does Clematis 'Jackmanii' need full sun?
- Full sun: at least 5 hours of direct sun a day.
- How much water does Clematis 'Jackmanii' need?
- Moderate water. Drought tolerance is low and waterlogging tolerance none.
- How cold-hardy is Clematis 'Jackmanii'?
- It tolerates about -34 °C (-29 °F) once established, roughly USDA zone 4.
- When does Clematis 'Jackmanii' flower?
- From about July for 11–16 weeks (northern hemisphere; later in cold climates, earlier in warm ones).
- Is Clematis 'Jackmanii' poisonous to cats and dogs?
- For cats it is mildly toxic; for dogs mildly toxic; for people moderately toxic. Contains ranunculin, which releases the irritant protoanemonin; sap blisters skin and mouth, and ingestion causes drooling and vomiting.
- What grows well with Clematis 'Jackmanii'?
- There is no well-documented companion pairing for Clematis 'Jackmanii'. Group it with plants that like the same sun (full sun) and water (moderate).
Sources and evidence
Evidence grade B (B: extension service or peer-reviewed).
- RHS Plant Finder, Royal Horticultural Society
- Missouri Botanical Garden Plant Finder, Missouri Botanical Garden
- ASPCA Toxic and Non-Toxic Plant List, ASPCA
Notes and assumptions
- Typical garden-form values; cultivars and local conditions differ.
- Pruning group 3: cut hard to about 30 cm in late winter. Prefers a sunny head with a cool, mulched, shaded root run. Susceptible to clematis wilt.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Hellebore (Lenten rose) Helleborus x hybridus
- Delphinium Delphinium elatum hybrids
- Common columbine Aquilegia vulgaris
- Japanese anemone Anemone hupehensis
- Larkspur Consolida ajacis
- Love-in-a-mist Nigella damascena
- Globeflower Trollius europaeus
- Christmas rose Helleborus niger