Bicolor monkshood
Aconitum x cammarum 'Bicolor' · Ranunculaceae
Branching spires of hooded flowers, white edged with violet-blue, over deeply cut dark leaves in the second half of summer.
- Size
- 4 ft tall, 18 in wide
- Zones
- 3 to 7
- Light
- Part sun to part shade
- Flowers
- Mid July to late August
- Pets
- Toxic (severe)
- Job in a bed
- Accent
A bed built around bicolor monkshood
The planner designed this bed around bicolor monkshood when this page was made: a 12 × 6 ft (3.7 × 1.8 m) cottage garden in zone 6, part sun. It chose the other plants from the 708 that suit those conditions, and says below why bicolor monkshood stands where it does.
The plants
- 1 Bicolor monkshood × 3, blue
- 2 Creeping mahonia × 8, yellow
- 3 Bloody cranesbill 'Max Frei' × 11, pink
- 4 Gray's sedge × 3, green
- 5 Purple gas plant × 1, pink
- 6 Blue-stemmed goldenrod × 3, yellow
- 7 Spring snowflake × 12, white
- 8 Meadow saffron × 8, pink
Why this plant
- The only blue.
Why here
- Anchors a back corner. At 4 ft it is the tallest plant here, and the tallest close the ends of the bed, where they stand in front of nothing.
- A step in the back row. Next to blue-stemmed goldenrod (2½ ft): no two neighbours there are the same height, so the back steps up and down like a skyline.
- 3 plants in one clump. A single spire is too slight to hold a place alone, so here the accent is a clump.
Why now
- In flower for 7 weeks. From mid July to late August.
- Part of the bed's peak. With bloody cranesbill 'Max Frei' and Gray's sedge in mid July: 3 kinds at once. No week has more.
Planned as a cottage garden: 29 of the 29 plants (100%), bulbs aside, stand alone or in groups of no more than five, small enough for the kinds to mingle. The back corners are held by bicolor monkshood and purple gas plant, the tallest plants on the plan. Creeping mahonia is planted in three places along the bed, which gives it rhythm. Every line of the Design check comes out Good or better.
The planner's own design check: 10 Excellent, 7 Good.
Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.
Where bicolor monkshood goes in a border
At 4 ft it belongs at the back of a bed. In the planner's ten height classes it is moderately tall (3 to 4 ft).
Its job: accent. An upright plant used singly, like a punctuation mark, and repeated at intervals to give the bed rhythm.
It gives the height and blue of a delphinium in part shade, later in the year, and needs no staking in most gardens. Plant it at the back, out of reach, and wear gloves when cutting it down.
- Late-summer height in part shade
- Cottage and woodland borders
- A delphinium substitute where summers are cool
What to plant with bicolor monkshood
Plants recorded as good partners for it, and what each pairing does:
- Japanese anemone: in flower together for two weeks, from mid August; happy in the same moist soil.
- Astilbe: in flower together for two weeks, from mid July; low enough (24 in) to stand in front of it; happy in the same moist soil.
- Goat's beard: flowers first, early June to late June, so the spot is never empty; happy in the same moist soil.
Questions about bicolor monkshood
Does bicolor monkshood need sun or shade?
Bicolor monkshood grows in part sun (4 to 6 hours of sun, including some afternoon sun) and part shade (2 to 4 hours of sun, mostly in the morning).
It wants soil that stays evenly moist, rich in organic matter, and a good soak in dry spells.
What zones does bicolor monkshood grow in?
USDA zones 3 to 7. It is hardy to zone 3, which means it survives winter nights down to about −30 °F (−34 °C).
Above zone 7 it struggles: the zones measure winter cold, but a plant's top zone usually means the summers are too hot or the winters too mild for it to rest.
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
When does bicolor monkshood flower in my zone?
In zone 5 it flowers mid July to late August. As a summer flower it moves about half a week for every zone: earlier where it is warmer.
| Zone 3 | Mid July to late August |
|---|---|
| Zone 4 | Mid July to late August |
| Zone 5 | Mid July to late August |
| Zone 6 | Mid July to late August |
| Zone 7 | Early July to mid August |
Worked out from Hopkins' bioclimatic law: spring arrives about four days later for each degree of latitude north, and one zone is roughly two degrees. A warm spring or a cold one moves any garden two weeks either way.
How far apart should bicolor monkshood be planted?
16 in (40 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 18 in (45 cm), so a group knits into one patch.
It grows 4 ft (120 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many bicolor monkshood plants do I need?
At 16 in apart, set out in staggered rows:
- 7 to fill 10 square feet (about 1 m²)
- 8 for a single row 10 ft (3 m) long
- 21 to fill a 4 × 8 ft bed on its own
In a mixed border, plant it as one at a time, repeated along the bed at intervals; a slender one reads better as a clump of three.
In the bed above, the planner used three in one group.
Is bicolor monkshood poisonous to dogs and cats?
Yes: severe toxicity to people, dogs, cats and horses. All parts are extremely poisonous if eaten, and the poison can be absorbed through the skin. Wear gloves to handle it, and never plant it near vegetables or where children play.
What flowers after bicolor monkshood?
Bicolor monkshood is over by late August. These start as it finishes and carry the same spot on, so it never goes flat:
- Japanese anemone: from mid August to early October, 3 ft tall, to stand in front of it and cover its fading stems (a recorded partner).
- Blue wood aster: from mid September to mid October, 3 ft tall, to stand in front of it and cover its fading stems.
- Zigzag goldenrod: from mid August to late September, 3 ft tall, to stand in front of it and cover its fading stems.
What does bicolor monkshood look like in winter?
Bicolor monkshood dies down to the ground and there is nothing to see until spring. The old stems can be cut in autumn, or left until spring as shelter for overwintering insects.
More Aconitum
- Autumn monkshood Aconitum carmichaelii 'Arendsii'
- Monkshood Aconitum napellus
In these guides
- Garden plants toxic to cats
- Garden plants toxic to dogs
- Tall perennials and grasses for the back of a border
- Plants with spires: vertical accents
- Plants with blue flowers
Every fact on record
- Type
- Perennial
- Size
- 4 ft (120 cm) tall, 18 in (45 cm) wide
- Plant
- 16 in (40 cm) apart
- Height class
- Moderately tall (3 to 4 ft)
- Place in the bed
- Back
- Flowers
- Mid July to late August; upright spires; blue, white
- Leaves
- Medium texture, herbaceous; dark green
- Shape
- Upright, clumping
- Hardy in
- USDA zones 3 to 7
- Light
- Part sun, part shade
- Soil
- Rich, evenly moist
- Water
- Moderate
- Feeding
- Light, in spring
- Family
- Ranunculaceae
Not yet checked against an outside reference: its figures rest on general horticultural knowledge. Flowering times are for zone 5: later in colder zones, earlier in warmer ones. Toxicity and spread information is a general gardening guide, not veterinary or medical advice, and invasive status varies by region. If a person or pet eats a plant, contact poison control or a vet. Check your local invasive species list before planting anything with a spread warning.