HARDINESS: Zones 3 to 7
PREFERRED SOIL pH: Neutral to slightly acid
PREFERRED SOIL TYPE: Fertile, moist, well-drained
PREFERRED LIGHT: Sun to partial shade
ATTRIBUTES Spikes of blue, pink, yellow, white, or blue-and-white flowers; for beds
SEASON OF INTEREST: Midsummer to early fall
FAVORITES: A. napellus and cultivars, A. carmichaelii, A. x cammarum 'Bicolor'
QUIRKS: All plant parts are poisonous if eaten
GOOD NEIGHBORS: Purple coneflower, rudbeckia, sneezeweed
WHERE IT GROWS BEST: In well-drained, fertile soil; areas with warm days and cool nights
POTENTIAL PROBLEMS: Root rot, verlicillium wilt when grown in wet soil
RENEWING PLANTS: Lives several years; do not divide
CRITTER RESISTANCE: Good
DIMENSIONS: 3-4 ft (1-1.2 m) tall, 2-3 ft (0.6-1 m) wide
Monkshood in the Landscape
If you've lusted after the tall blue spires of delphiniums but found that they are too finicky to grow, try the far less fussy monkshood. This native of mountains and alpine meadows stands 3-4 ft (1-1.2 m) tall and sends up spikes of blue, pink, yellow, or white-arid-blue hooded blossoms between midsummer and early fall.
The dark green foliage is deeply divided and clothes the base of the plants with a skirt of lush greenery.
Monkshood is an old-fashioned flower perfectly suited to cottage gardens or casual borders. It should be placed at the back of the border because of its height and also because it should be kept away from children and pets who might be tempted to take a bite of its poisonous leaves, stems, and flowers. Some good companions of comparable size with similar bloom times include rudbeckia, cohosh, obedient plant, purple cone-flower, and sneezeweed.
A healthy monkshood will brandish several spires of flowers arranged all around the stem that open from the top down. Each blossom has an unusual shape, with the uppermost petal forming a helmet or hood,
hence the common name. The plants may become so heavily laden with blossoms that they need to be staked. Use inconspicuous plastic or bamboo stakes and fasten the stems to them with soft green twine, raffia, or yarn. If carefully installed, the stakes will be scarcely visible.
Beyond Blue Hues
The monkshood family has a number of worthwhile relatives that expand the color range beyond the fetching azure found in the traditional monkshoods, Aconitum napellus and its equally well known cousin, A. carmichadii. There's a white-flowered cultivar, A. napellus ssp. vulgare 'Album', and two pink versions: 'Carneum' in salmon and 'Roseum' in shell pink. A. lycotonum ssp. neapolitanum has abundant yellow flowers, while 'Ivorine' has pale ivory-yellow blossoms. For a charming color combination, try A x cammarum 'Bicolor' or 'Eleanor', both of which have white flowers edged in blue.
Where it is happy, monkshood is as care-free as it is stunning. It excels in areas with cool summer weather but flags where hot, humid summers are the rule. In warm climates, grow monkshood in partial shade and mulch to keep roots cool and moist.
Monkshood demands well-drained and fertile soil, so dig in plenty of compost or other organic matter prior to planting. The roots of all monkhoods are particularly poisonous; be sure to handle plants with gloves when planting. Position plants in a permanent home, because monkshood roots are brittle and rarely survive disturbance. It is also best not to divide them.
Monkshood is prone to two diseases linked to poor soil drainage. Crown rot causes leaf yellowing and brown streaks in the foliage; verticillium wilt causes yellowing on one side of the plant only. To prevent these problems, allow soil to dry between waterings and plant in a well-drained location. Because of its toxicity, monkshood is virtually pest free.