Hardy geraniums are the most popular perennials in Britain. And it’s easy to see why. They’re tough and easy to grow, many flowering for months at a stretch
What’s the difference between a geranium and a pelagonium? ‘Geranium’ is the name most people use when talking about pelargoniums. But Geranium is actually a different plant genus. To help avoid confusion some refer to Geranium as ‘hardy geraniums’, and Pelargonium as ‘tender geraniums’. Discover 10 hardy geraniums perfect for your garden, which have been awarded the RHS Award of Garden Merit (AGM).
Geranium ‘Johnson’s Blue’ vs ‘Rozanne’ – Which Hardy Geranium is Best for Your Garden?
Geranium ‘Johnson’s Blue’ and ‘Rozanne’ are two of the most popular hardy geranium varieties grown today, Both offer stunning purple-blue blooms on carefree plants But there are some key differences between these two perennials that are worth exploring when making your choice
An Overview of ‘Johnson’s Blue’ and ‘Rozanne’
‘Johnson’s Blue’ is a classic English cottage garden plant that has been popular since its introduction in the 1940s. It forms a compact mounding plant reaching 12-18 inches tall and wide. The 2 inch saucer-shaped flowers are a rich violet-blue with a white center. It blooms vigorously for 3-4 weeks in early summer.
‘Rozanne’ is a newer variety introduced in 2000. It has a more sprawling habit reaching 18-24 inches tall and up to 3 feet wide. The larger 2.5 inch flowers are a similar violet-blue but have a more open form with ruffled petals. ‘Rozanne’ blooms for an exceptionally long time, from early summer until frost.
Both are cold hardy in zones 4-8 and have minimal care needs when established. They prefer full sun to part shade and average, well-drained soil.
Flowering Time and Abundance
The biggest difference between these geraniums is their flowering performance.
‘Johnson’s Blue’ blooms abundantly for 3-4 weeks in early summer. Flowering starts in early June, peaks in mid June, and winds down in early July. The flowers are produced in clusters, completely smothering the foliage in rich color.
‘Rozanne’ blooms for a much longer period, from early summer into fall. However, it does not flower as prolifically at peak bloom time. The blooms are produced steadily but sporadically, with just single blooms appearing amongst the foliage from July through October.
So while ‘Rozanne’ offers months of color, ‘Johnson’s Blue’ delivers a bolder floral display for a few weeks when in peak bloom. If you want intense early summer flowers, ‘Johnson’s Blue’ is the better pick. For continued color all season, choose ‘Rozanne’.
Growth Habit and Foliage
These geraniums have quite different habits, which suits them for different uses:
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‘Johnson’s Blue’ forms a compact, mounding plant that maintains its tidy shape all season. It reaches 18 inches tall and wide. The medium green leaves are lightly textured.
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‘Rozanne’ has a more open, spreading habit. It can reach 24 inches tall but spreads to 3 feet wide. The larger leaves have bolder veining and chartreuse marbling.
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The sprawling stems of ‘Rozanne’ tend to flop, so cutting it back after blooming improves its form. ‘Johnson’s Blue’ is better behaved.
Hardiness and Care Needs
Both ‘Johnson’s Blue’ and ‘Rozanne’ are tough, hardy geraniums that are easy to grow. Their care needs are similar:
- Full sun to part shade
- Average, well-drained soil
- Moderate watering, avoid wet feet
- Cut back after flowering
- Divide congested plants every 3-5 years
‘Rozanne’ appreciates a bit more sun to flower its best. ‘Johnson’s Blue’ handles more shade. Over time, both can be prone to leaf spots, which is prevented by good air flow and pruning. Overall, ‘Johnson’s Blue’ tends to be slightly easier care.
Uses in the Garden
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‘Johnson’s Blue’ is perfect for the front of borders, edging paths, and containers. It forms a tidy dome shape.
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‘Rozanne’ can be used in borders but shines spilling over walls, slopes, steps and retaining walls with its spreading form.
The ideal ground cover
One of the finest of recent hardy geraniums, Geranium ‘Orion’ could be said to be like good old Geranium × johnsonii ‘Johnson’s Blue’ – only far, far better. Spreading to make excellent ground cover, large lavender-tinted blue flowers have purple veins and open in huge quantities all summer. The broad petals overlap to create bowl-shaped flowers and the white centres accentuate the colouring. A seedling of Geranium ‘Brookside’, another fine AGM winner. 75cm (30in). Hardiness rating H7.
Geranium ‘Mavis Simpson’ is a low and spreading, almost evergreen plant. It has lobed silvery foliage which makes a lovely background for the pink flowers which themselves have a silver overlay as well as dark veins. Flowers open from June to October and although the stems spread widely they’re easy to restrict as they do not take root. Found as a chance seedling at Kew, and named after a Kew gardener. 20cm (8in). Hardiness rating H6.
A prolific, widely spreading and unusually long flowering ground cover, the purple-veined magenta pink flowers open from July until a hard frost. Although unhappy in dry conditions, Geranium ‘Dilys’ is valuable for its tolerance of poor drainage and enjoys part shade as well as in full sun. Named in honour of Dilys Davies, for many years an influential member of the Hardy Plant Society. 40cm (16in). Hardiness rating H7.
Purple veins, purple veins
Geranium Rozanne (‘Gerwat’) is a stupendous plant making vigorous ground cover or a dramatic container specimen. The prolific saucer-shaped flowers open from July to October and feature purple veins and a bold white centre – all set against fresh green foliage. It needs plenty of space, or is superb planted as a specimen in a large container where it creates a blue waterfall of colour. ‘Jolly Bee’ has now been pronounced as identical. 60cm (2ft). Hardiness rating H7.
With some of the loveliest foliage of all hardy geraniums, each broad lobed greyish leaf of Geranium renardii has the soft texture of sage foliage. In June and July sprays of white flowers with deep purple veins are held just above the even mound of leaves. This is a compact and slowly spreading plant, ideal for the front of a sunny border; dryish conditions bring out the best in the foliage. 35cm (14in). Hardiness rating H6.
This delicately patterned form of our
A native plant is one that originated or arrived naturally in a particular place without human involvement. In the British Isles, native plants are those that were here during the last ice age or have arrived unaided since.
native Geranium pratense (meadow cranesbill) is effective close up, where its intricate colouring can be admired, and from a distance for its haze of colour. The pale blue flowers of Geranium pratense ‘Mrs Kendall Clark’, which open through June and July, feature a network of white veins and will come again in a second flush if dead-headed. In spring, the mound of new lobed foliage is also attractive. 90cm (3ft). Hardiness rating H7.
Many varieties of this widely grown
A plant produced by crossing two distinct parents, often different species, to produce offspring that combine the characteristics of both. Hybrids can occur naturally, but crosses are often made deliberately by plant breeders to produce plants with better yield, improved flowering or vigour, or improved disease resistance.
hybrid are weedy, floppy and unremarkable but Geranium x oxonianum ‘Wageningen’ is more compact, more upright and has a long succession of green eyed, salmony pink flowers each with a shiny reflective surface to enhance the appeal. Superb under old roses, in full sun the flowers may bleach so partial or dappled shade is ideal. ‘Wageningen’ is happy in most soils. 40cm (18in). Hardiness rating H7.
Hardy Geraniums: Amazing Perennials with Up to 4 Seasons of Interest! // Garden Answer
FAQ
What is the difference between geranium Rozanne and Johnson’s blue?
‘Johnson’s Blue’ forms 18” mounds of cornflower blue flowers that grace my perennial bed for the month of June. ‘Rozanne’, awarded the title of “2008 Perennial Plant of the Year”, is taller with 2.5 inch violet-blue flowers that bloom all summer, and deep green foliage lightly marbled with chartreuse.
What is the longest flowering blue geranium?
GERANIUM Rozanne (‘Gerwat’PBR)
‘Rozanne’ carries masses of large, vivid violet-blue saucer-like flowers with distinct white centres and star-like reddish-purple veins over spreading mounds of dark green foliage. This is the longest flowering Geranium we know, lasting all summer into the autumn.
What are the longest blooming hardy geraniums?
Geranium Rozanne® is the longest blooming and most prolific blue-flowered Geranium in our garden. Flowers start in early summer and continue through midsummer’s heat into autumn on fast-growing plants, which are spreading but not sprawling and make an attractive ground cover.
What is the most beautiful hardy geranium?
Geranium Rozanne (Cranesbill)
Geranium Rozanne is an exceptional and unmatched perennial with an extended flowering period. Its stunning blue flowers, adorned with purple veins and white centers, bring unparalleled beauty to gardens, patios, or balconies.