Common Name: azure monkshood
Type: Herbaceous perennial
Zone: 3 to 7
Height: 2.00 to 3.00 feet
Spread: 1.50 to 2.50 feet
Bloom Time: August to September
Bloom Description: Deep purple (inside) and pale blue (outside)
Sun: Full sun to part shade
Best grown in moist, organically rich, well-drained soils in full sun to part shade. Soils must not be allowed to dry out, but need sufficient drainage to prevent wet conditions from developing. Best in full sun in cool summer climates. Appreciates some afternoon shade in the St. Louis area. Needs cool nights below 70 degrees F. to grow well, and, like the related delphiniums, will often struggle in hot St. Louis summers. Cut back stems after flowering to encourage an additional late season bloom. Although plants may be propagated by division, they are often slow to establish and are probably best left undisturbed once planted.
Native to central China, this species of monkshood is sometimes commonly called autumn-flowering monkshood because of its late summer to early fall bloom. It blooms later than most other species of Aconitum. It is an erect, tuberous-rooted perennial that features dense panicles (to 8” long) of hooded flowers atop rigid, leafy stems typically growing 2-3’ tall. In optimum growing conditions, plants may grow 4-5’ tall. Species flowers are deep purple inside and paler blue outside. The upper sepal of each flower develops into a large, helmet-like structure that somewhat resembles the hood worn by medieval monks, hence the common names of monkshood and helmet flower. Leathery, dark green leaves are deeply divided into 3-5 lobes. All parts of the plant (especially the roots and seeds) are extremely poisonous. Arendsii group hybrids (A. carmichaelii x A. carmichaelii var. wilsonii) feature uniformly deep azure blue flowers. Species is sometimes sold as A. fischeri.
No serious insect or disease problems. Crown rot, powdery mildew and verticillium wilt are occasional problems. Generally does not need staking or other support. WEAR GLOVES WHEN WORKING WITH THIS PLANT. Avoid skin or oral contact with plant juices, and be particularly careful to cover up any open cuts or skin abrasions prior to entering garden areas.
In the St. Louis area, this plant needs consistently moist soils and may be best grown in moist woodland areas, along streams or ponds, or on the periphery of bog or water gardens. Will grow in borders as long as the soil moisture requirements can be met. Because of the poisonous properties of the plant, it probably should not be grown in areas where small children might come in contact with it or in areas contiguous to vegetable gardens where tubers are growing.