Cranesbill 'Johnson's Blue'
Geranium 'Johnson's Blue' ·
Clear, lavender-blue saucers in early summer over a mound of finely cut leaves. The classic blue cranesbill, though it flowers for only a month.
- Size
- 18 in tall, 24 in wide
- Zones
- 4 to 8
- Light
- Full sun to part sun
- Flowers
- Late May to early July
- Pets
- Not checked
- Job in a bed
- Drift
A bed built around cranesbill 'Johnson's Blue'
The planner designed this bed around cranesbill 'Johnson's Blue' when this page was made: a 12 × 6 ft (3.7 × 1.8 m) English border in zone 6, full sun. It chose the other plants from the 966 that suit those conditions, and says below why cranesbill 'Johnson's Blue' stands where it does.
The plants
- 1 Cranesbill 'Johnson's Blue' × 1, blue
- 2 Winter heath × 13, pink
- 3 Sea thrift × 11, white
- 4 False sunflower 'Summer Nights' × 3, yellow
- 5 Little bluestem 'The Blues' × 8, tan
- 6 Silver sage × 1, silver leaves
- 7 Hardy gladiolus × 4, pink
- 8 Red spider lily × 5, red
Why this plant
- The only open bowls. The others are bells, globes, daisies and others. Shape reads at a distance, where colours blur.
- The only blue.
Why here
- In the middle. At 18 in it is the step between silver sage (12 in) in front and little bluestem 'The Blues' (3 ft) behind: each is seen over the one before.
- One plant. Three or more is usual for a plant of this kind, and reads better.
Why now
- In flower for six weeks. From late May to early July.
- Fills a gap. For one of those weeks nothing else on the plan is in flower.
Planned as an English border: 6 of the 7 groups (86%) are drifts, longer along the bed than they are deep. The back corners are held by little bluestem 'The Blues' and false sunflower 'Summer Nights', the tallest plants on the plan. There is more winter heath than anything else, 13 plants in all.
The planner's own design check: 13 Excellent, 2 Good, 2 Satisfactory. It flags one thing to watch: Nothing on this plan is highly poisonous or an aggressive spreader.
Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.
Where cranesbill 'Johnson's Blue' goes in a border
At 18 in it belongs at the front of a bed. In the planner's ten height classes it is short (12 to 18 in).
Its job: drift. Planted in a small group of three or five, and repeated further along in the other number.
The blue that English gardeners plant under old roses and beside lady's mantle. 'Rozanne' flowers far longer, but this is earlier and a truer blue. Cut it back after flowering for fresh leaves.
- Blue beneath roses and peonies
- The front to middle of a border
- Cottage gardens
What to plant with cranesbill 'Johnson's Blue'
Plants recorded as good partners for it, and what each pairing does:
- Peony: in flower together for four weeks, from late May; tall enough (3 ft) to stand behind it.
- Lady's mantle: in flower together for six weeks, from late May.
- Siberian iris: in flower together for four weeks, from late May; tall enough (2½ ft) to stand behind it.
Questions about cranesbill 'Johnson's Blue'
Does cranesbill 'Johnson's Blue' need sun or shade?
Cranesbill 'Johnson's Blue' grows in full sun (6 or more hours of direct sun a day) and part sun (4 to 6 hours of sun, including some afternoon sun).
It wants ordinary well-drained soil, of average fertility, and a good soak in dry spells.
What zones does cranesbill 'Johnson's Blue' grow in?
USDA zones 4 to 8. It is hardy to zone 4, which means it survives winter nights down to about −20 °F (−29 °C).
Above zone 8 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 cranesbill 'Johnson's Blue' flower in my zone?
In zone 5 it flowers late May to early July. As a spring flower it moves about a week for every zone: earlier where it is warmer, later where it is colder.
| Zone 4 | Early June to mid July |
|---|---|
| Zone 5 | Late May to early July |
| Zone 6 | Late May to early July |
| Zone 7 | Mid May to late June |
| Zone 8 | Early May to late June |
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 cranesbill 'Johnson's Blue' be planted?
24 in (60 cm) apart, from the middle of one plant to the middle of the next. That is about its full width, so each plant keeps its own outline.
It grows 18 in (45 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many cranesbill 'Johnson's Blue' plants do I need?
At 24 in apart, set out in staggered rows:
- 3 to fill 10 square feet (about 1 m²)
- 6 for a single row 10 ft (3 m) long
- 10 to fill a 4 × 8 ft bed on its own
In a mixed border, plant it as a group of three or five, with a second group further along in the other number.
In the bed above, the planner used one in one group.
What flowers after cranesbill 'Johnson's Blue'?
Cranesbill 'Johnson's Blue' is over by early July. These start as it finishes and carry the same spot on, so it never goes flat:
- Black-eyed Susan: from mid July to mid September, 24 in tall.
- Butterfly weed: from late June to early August, 24 in tall.
- Daylily: from late June to early August, 2½ ft tall.
What does cranesbill 'Johnson's Blue' look like in winter?
Cranesbill 'Johnson's Blue' 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 Geranium
- Armenian cranesbill Geranium psilostemon
- Bigroot cranesbill Geranium macrorrhizum
- Bigroot cranesbill 'Bevan's Variety' Geranium macrorrhizum 'Bevan's Variety'
- Bigroot cranesbill 'Ingwersen's Variety' Geranium macrorrhizum 'Ingwersen's Variety'
- Bloody cranesbill Geranium sanguineum
- Bloody cranesbill 'Max Frei' Geranium sanguineum 'Max Frei'
- Cranesbill 'Ann Folkard' Geranium 'Ann Folkard'
- Cranesbill 'Azure Rush' Geranium 'Azure Rush'
- Cranesbill 'Ballerina' Geranium cinereum 'Ballerina'
- Cranesbill 'Biokovo' Geranium x cantabrigiense 'Biokovo'
- Cranesbill 'Brookside' Geranium 'Brookside'
- Cranesbill 'Karmina' Geranium x cantabrigiense 'Karmina'
- Cranesbill 'Orion' Geranium 'Orion'
- Cranesbill 'Rozanne' Geranium 'Gerwat' (Rozanne)
- Cranesbill 'Wargrave Pink' Geranium x oxonianum 'Wargrave Pink'
- Dalmatian cranesbill Geranium dalmaticum
- Himalayan cranesbill Geranium himalayense
- Meadow cranesbill Geranium pratense
- Meadow cranesbill 'Midnight Reiter' Geranium pratense 'Midnight Reiter'
- Mourning widow Geranium phaeum
- Mourning widow 'Samobor' Geranium phaeum 'Samobor'
- Renard's cranesbill Geranium renardii
- Showy cranesbill Geranium x magnificum
- Striped bloody cranesbill Geranium sanguineum var. striatum
- Wild geranium Geranium maculatum
- Wild geranium 'Espresso' Geranium maculatum 'Espresso'
In these guides
Every fact on record
- Type
- Perennial
- Size
- 18 in (45 cm) tall, 24 in (60 cm) wide
- Plant
- 24 in (60 cm) apart
- Height class
- Short (12 to 18 in)
- Place in the bed
- Front
- Flowers
- Late May to early July; open bowls; blue
- Leaves
- Medium texture, herbaceous; green
- Shape
- Mounding, clumping
- Hardy in
- USDA zones 4 to 8
- Light
- Full sun, part sun
- Soil
- Average, well-drained
- Water
- Moderate
- Feeding
- Light, in spring
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.