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Geranium 'Johnson's Blue'


Who else was raised thinking geraniums were red, white, pink or orange, usually found in hanging pots or in window boxes? That was my understanding, until I was schooled at the nurseries where I worked later in life. The bright-colored flowers I knew as geraniums were actually Pelargoniums. Still in the same family, "geranium" is their common name. Whereas Geranium is a particular genus that our 'Johnson's Blue' belongs. Purples, pinks, and white are available from other species, but G. 'Johnson Blue' is the bluest (although it still has a bit of purple in the coloring). What do you think? Is it blue or purple? Maybe the best way to answer is to look in person rather than the photos available on the internet.


Like other Geraniums, 'Johnson's Blue' is a billowy mound of leaves with its flower stems rising slightly above. The flower stalks can become a little floppy under the weight of the flowers, especially when wet. They should bounce back after drying. A worthwhile addition to perennial borders, Johnson's Blue cranesbill, if you want to give it a common name, is hardy despite its delicate appeal. As with most Geraniums, they can also be added as an understory to larger plants. The Royal Horticulture Society recommends planting them under roses or other shrubs, but of course it all depends on which ones allowing plants and blooms under their limbs.


 

facts

Botanical Name: Gerainum 'Johnson's Blue'

Geranium: Greek, geranos for crane. The fruit looks like a crane's bill.

Common Name: Johnson's blue cranesbill

Family Name: Geraniaceae


Origin: South Africa; parent origin not confirmed at time of posting.


design considerations


Positioning: Foreground, forest edge, ground cover underplanting

Garden Themes: Perennial, woodland, rock, cottage, pollinator

Uses: Edging, borders, mass, containers


identifying characteristics


Type: Herbaceous perennial

Form: Mound

Texture: Coarse

Size: 18" tall and spreading


Outstanding Feature(s): Flower


Stems: Rhizome

Leaf:

  • Type: Simple

  • Arrangement: Alternate

  • Shape: Palmate

  • Margin: Lobed

  • Color: Medium to light green, may turn red/orange/yellow in autumn.

  • Surface:

Flower: Spring to Autumn. Open cymes, slightly cupped blue-violet. Showy.

Fruit: May produce seed with the appearance of a cranes bill.


cultural requirements, tolerances & problems


Sunset Zones: A2, A3; 2-9, 14-24

USDA Zones: 4-8


Light: Sun (coastal), light shade to partial shade (inland)

WUCOLS SF Bay Area Hydro Zone: Moderate

Soil:

  • Texture: Sand, loam, clay, chalk, well composted

  • Moisture Retention: Well-drained

  • pH: Slightly acidic to alkaline

Tolerances: Dear, drought

Problems:

  • Branch Strength: N/A

  • Insects: Vine weevil

  • Disease: Leaf spot, rust, powdery mildew


citations & attributions


Bayton, R. (2019). The Royal Horticultural Society's the Gardener's Botanical: An Encyclopedia of Latin Plant Names. London: Mitchell Beazley.


Norris Brenzel, K. (Ed.). (2012). The New Sunset Western Garden Book. New York: Time Home Entertainment, Inc.


Plant Finder. "Geranium 'Johnson's Blue'." Missouri Botanical Garden, St. Louis. Accessed on August 30, 2021, from https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=d101.


RHS. "Geranium × johnsonii 'Johnson's Blue'." The Royal Horticulture Society, London. Accessed on August 30, 2021, from https://www.rhs.org.uk/Plants/95458/Geranium-Johnson-s-Blue/Details.


Water Use Classification of Landscape Species. "WUCOLS IV Plant List." University of California, Division of Agriculture and Natural Resources, Davis. Accessed on July 27, 2021.

https://ucanr.edu/sites/WUCOLS/Download_WUCOLS_IV_List/.


Photos:


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