Plant of the Month August 2025
GENERAL INFORMATION: There are over 250 species of Aconitum. These are poisonous members of the Buttercup family with a toxin can be absorbed through the skin. A. hemsleyanum climbs by twining stems. My plant came from the late Harry Lumsden. It is not happy after deck renewal and this hot dry Toronto summer.
Common Name: Climbing Monkshood, aconite, monkshood, wolfsbane, leopard's bane, devil's helmet.
Cultivars: Aconitum hemsleyanum ‘Red Wine’.
Life Cycle: Vine. Dies down in winter in Toronto.
Range: Central and Western China.
Habitat: Woodland edges.
Height: 2-3 m.
Bloom Time: August to September in Southern Ontario.
Aconitum hemsleyanum.
Flower Colour & Size: Five petaloid sepals with the upper sepal forming a yellow-green, blue tinged helmet or hood (galea) with blue veining. The true petals are two nectaries within the hood, plus some scales around numerous stamens.
Aconitum hemsleyanum - close up.
Scent: Not noticeable.
Stems: Dark red brown, twining.
Leaves: Mid-dark green, three deeply divided compound pinnate leaflets.
Aconitum hemsleyanum - leaves.
Fruit: Erect follicles 1.5 cm long with several seeds.
CULTIVATION:
Plant: Poisonous. Especially roots and seeds. Position with care. Allow to scramble through other deciduous shrubs.
Light: Full sun to part shade. Avoid hot mid-day sun.
Soil: Most well drained damp soils, preferably with plenty of organic material.
Water: Medium amounts. Must not dry out. Avoid any standing water.
USDA Hardiness: Zones 4-8.
Pests and Diseases: Aphids? Usually pest free.
Companion planting: Yellow Clematis.
Pollinators: Long-tongued bumblebees. May attract hummingbirds.
Propagation: By seed or careful division.
Seedex availability: Sometimes in seed exchanges.
Germination Tips: Poisonous. Handle with care. Plant seed fresh. Otherwise try 20°C x 4 weeks, then -7°C x 6 weeks, then 10°C. Slow.
Sadly, my plant was damaged by deck construction and is probably dead. NB - grow a second plant if difficullt to replace.
References:
Wikipedia.
https://www.rhs.org.uk/plants/46855/aconitum-hemsleyanum/details
Text and images supplied by Anna Leggatt