Monkshood is tall, delphinium-like plant with hooded blue or purple flowers. Monkshood can be used as a tall foundation plant, in semi-wild gardens, and in lightly shade borders.
Monkshood is slow growing at first but grows faster once established. Monkshood may struggle where summers are hot or where nighttime temperatures are greater than 70°F (21°C).
One note: Monkshood is poisonous and should grow out of reach of children.
Get to Know Monkshood
- Plant type: Perennial
- Growing zones and range: 3-7
- Hardiness: Hardy perennial; will die back with frost
- Height and width: 2 to 3 feet tall 61-91cm) and 2 to 3 feet wide.
- Flower form: blue flowers
- Bloom time: Mid to late summer to early fall; good color for the fall garden.
- Uses: Good choice for the middle to the back of beds and borders; a good addition to shady beds and woodland gardens.
- Garden companions: Globe thistle, meadow phlox, goatsbeard, fragrant bugbane
- Botanical name: Acontium carmichaelii
- Common name: Azure monkshood
Where to Plant Monkshood
- Plant monkshood in full sun to light shade; afternoon shade is best. Monkshood thrives in shade.
- Monkshood prefers well-drained, humus-rich soil. Add plenty of aged compost to the planting bed ahead of planting.
When to Plant Monkshood
- Plant established plants in spring or fall.
- Transplant starts outdoors in late spring.
- Sow seed outdoors after the last frost in spring.
Planting and Spacing Monkshood
- Space monkshood 2 to 3 feet (61-91cm) apart.
How to Water and Feed Monkshood
- Water monkshood moderately unless it is in full sun. In full sun, water more often.
- Mulch to conserve soil moisture and keep roots cool in warm and hot regions.
- Feed with a slow-release fertilizer or feed every 6 weeks with a bloom-boosting fertilizer.
- Monkshood does not like to be divided or transplanted.
- Stake plants that grow tall and floppy.
- Monkshood can be prone to crown rot or mildew in wet and rainy regions.
- Divide monkshood every 3 to 4 years. Handle the roots carefully.
Monkshood Varieties to Grow
- Monkshood cultivars have either blue or violet flowers. ‘Bicolor’ has blue-and-white flowers. ‘Bressingham Spire’ is violet-blue and long blooming. ‘Eleonara’ has white flowers.
Monkshood Is Poisonous
- Monkshood is poisonous. Do not plant it where curious children, adults, or pets can reach it. Contact with foliage can cause a rash.