Purple petals with a clear white centre and violet veins keep coming from late spring right up to the first autumn frosts. Geranium Rozanne, whose true cultivar name is ‘Gerwat’, is one of the most generous and longest-flowering perennial ground covers there is. Give it sun and drainage, and it flowers for months.
| Name | Geranium ‘Gerwat’ |
|---|---|
| Trademark | Geranium Rozanne™ |
| Family | Geraniaceae |
| Type | perennial |
| Height | 16 to 20 inches (40 to 50 cm) |
| Exposure | full sun, part sun |
| Soil | ordinary but well drained |
| Flowering | late spring to mid-autumn |
Ideal for ground cover and well suited to growing in pots or pot arrangements, geranium Rozanne also offers a very long-lasting blooming.
Preferably in fall or spring in a mix that includes geranium-specific soil mix.
Space plants around 8 to 16 inches (20 to 40 cm) apart.
Since Geranium Rozanne is a sterile hybrid, it will never produce seeds.
The geranium Rozanne requires next to no care, like other perennial geranium.
Cut back stems eventually after they have flowered in order to trigger production of new flowers and avoid draining your perennial geranium.
This pruning will also keep your Rozanne from getting leggy and spreading too far: cut branches back by half to trigger new branching out. You can do this in any season, but there are differences:
As resistant to diseases as it is hardy, no known disease seems to infect geranium Rozanne.
Leaves and smaller stems will die back with the cold.
For sustained blooming, water often but make sure excess water drains out.
The same plant asks for different things at different times of year, and the pruning in particular changes with the season. Here is what each season calls for.
| Season | What to do | Why it matters |
|---|---|---|
| Spring | Cut back only the longest branches by half, then prune a few more once new leaves open on them | Shrinks the clump gradually without checking growth |
| Summer | Water often, but only where excess water can drain away | Sustains the bloom; damp is a greater threat than heat |
| Autumn | Plant or divide the crown, using a geranium soil mix | The main window for planting and for propagating |
| Winter | Cut all the stems back at once and mulch the base | Clears the dieback and protects the crown until spring shoots |
Beyond these few gestures the plant asks for next to nothing.
This perennial is among the most abundant flower-bearing geraniums. More than anything, it is among those that bloom over the longest period. Indeed, the blooming extends from late spring up to the first fall frost spells. It can withstand summer heat.
Care, heat resistance and water needs are identical to those of Sunpatiens, another great sun-loving flower.
In a flower bed and also along edges and in rocky ground, geranium Rozanne can serve as excellent ground cover (like the Patricia geranium) and beautiful garden box items.
Geranium Rozanne was first bred and discovered in 1989, by Donald and Rozanne Waterer. They were growing several dozens of Geranium plants which Rozanne loved. One year, a particularly vigorous specimen appeared in their garden in Somerset in the United Kingdom. It flowered profusely the next year from spring to first frost. Rozanne had never seen such a bloom! Parent plants were Geranium himalayense and Geranium wallichianum.
The couple was already familiar with horticulture, since Donald had been born and raised in a family that loved gardening (they had bred many hardy azalea varieties in their heyday). He had managed it and this discovery came after he had retired. They got in touch with flower expert Graham Stuart Thomas.
Graham Thomas was already famed for his work on preserving old English roses heritage breeds. He guided the Waterers towards Adrian Bloom (of Blooms of Bressingham), a well-known horticulturist. After propagating, growing and testing the plant, they were able to patent it as a new development!
Thus the plant was originally protected by a plant patent. The botanical name is actually “Gerwat”, which stands for Geranium and Waterer. “Rozanne” is the trademark name that the plant was marketed under, in honor of Mrs. Waterer.
After 2 decades, this patent has expired in late winter 2019 (for the United States and GATT signatory countries). It’s now allowed to propagate your own, and even sell them!
It’s a beautiful example of how a passion for flowers can spread the world, since millions of specimens have been sold throughout the world.
You can provide it with geranium-specific organic liquid fertilizer once or twice in the season to increase blooming.
Also, Geranium Rozanne prefers slightly acidic soil rather than alkaline soil, so a good mulch to use is pine bark mulch or even coffee grounds.
