Hardy geraniums, also known as cranesbills for their long beak-like seed-pods, are brilliant plants for the garden. They are different from, though distantly related to, pelargoniums, commonly, but wrongly, called geraniums – lovely plants, but tender, so are used for summer bedding, window boxes and pots.
Hardy geraniums are very obliging plants, reliable and easy to grow. They are herbaceous perennials, dying back in winter but putting out fresh new growth quite early in spring. Their deeply cut leaves are very attractive, many colouring well in autumn, and some, like Geranium renardii, are virtually evergreen. They are very good for pollinators, like bees and hoverflies.
Some hardy geraniums are sterile hybrids – they don't set seed – so they go on flowering for months and months. Some are great ‘filler’ plants, spreading out harmlessly and even climbing through the stick-like stems of tall roses and other shrubs; others are neat and compact, ideal for the front of a border.
How to grow hardy geraniums
Hardy geraniums do well in partial shade; some, like the small alpine cultivars, do better in full sun, and some, like the Geranium macrorrhizum cultivars, even cope with full, even dry, shade. They are really hardy, and cope with most soils, even chalky soils, as long as they’re reasonably fertile and free-draining, although most prefer a moist soil, especially if planted in full or afternoon sun. What they will not cope with is soil that lies heavy and wet in winter. They don’t generally do well in pots, unless the pots are very large; they are better in the ground, where most provide excellent ground cover.
They are tough plants, needing very little care, as rabbits, slugs and snails don't go for them. It’s good practice to give them a mulch of compost or manure in spring, to feed them and conserve moisture, particularly if grown in full or strong midday and afternoon sun or on dry, sandy soils. All hardy geraniums produce a flush of flowers in early summer, and when these go over, cut back hard with a shears and give a good watering, and new foliage will soon appear, forming a pleasing mound, and there will usually be a second flush of flowers.
Some hardy geraniums seed about, the seeds scattering explosively from the cranesbill-like seed-pod, so you can lift the seedlings to increase your stock. Others are rhizomatous, spreading gently about, and daughter-plants can be detached from the parent and planted elsewhere. Most can easily be divided in spring, replanting the divisions into the warming soil. The sterile varieties must be divided, of course.
Some good cultivars to grow
A paragon among hardy geraniums, with abundant, saucer-shaped, soft lavender-blue flowers with purple veins and a pinkish-white centre, fading to white, showing well against downy, lightly marbled, green foliage that sometimes colours in autumn.
As a sterile hybrid, it flowers from June until the first frosts in October. It’s a big, vigorous geranium, 2’ (60cm) x 3’ (1m), so needs plenty of space, making good ground-cover, although it is not invasive.
It has a small crown, so will spread gratifyingly to cover the dying leaves of the earliest spring bulbs. It likes a moist but well-drained soil, and full sun or partial shade, and tolerates inland exposure. Geranium Rozanne is, unusually, quite good in a large pot, its lax habit and endless flowering making a flowing cascade of flowers.
This geranium is impossible to divide, and needs to be micro-propagated; it is protected by Plant Breeders Rights. Geranium Rozanne holds the RHS Award of Garden Merit, and was named RHS Plant of the Centenary.
This very floriferous, easy cranesbill has abundant, clear, violet-blue, saucer-shaped flowers with fine reddish veins and a small white centre, on shortish stems over deeply cut, yellow-green leaves, which turn red-orange in autumn. A mat-forming herbaceous perennial, about 2’/60cm tall and 20”/50cm wide, it is best in full sun or partial shade, but will tolerate full shade, where the leaves make an attractive splash of light.
It will grow in any well-drained soil, preferably moist, and does need cutting back after the first flush of flowers, as it can grow a little straggly. It flowers from June to August, sometimes with a second flush of flowers, and holds the RHS Award of Garden Merit.
A chance seedling of Geranium Brookside, with meadow geranium ancestry as well, the brilliant cultivar Orion has masses of very deep violet-blue, almost indigo, saucer-shaped, 2”/5cm flowers with purple-maroon veins and a small greenish-white ‘eye’; the flowers are particularly luminous in morning and evening light.
It is a sterile hybrid, and flowers from May until well into autumn. The leaves are deeply cut and mid-green, turning reddish in autumn, and the flowers are held well clear of the foliage. It likes an open position, in full sun, as it grows lax and floppy in shade.
Orion looks particularly lovely with lemon-yellow flowers, creamy-buff or apricot roses (into which it will climb) and lavenders that pick up on its deep violet-blue colour. Another with a small crown, it’s good for covering the dying leaves of early spring bulbs. Cut back in July after the first flush of flowers, and leaves will appear within days, and then yet more flowers. Divide in spring. It holds the RHS Award of Garden Merit.
An easy-to-grow hardy geranium with G. psilostemon ancestry, it has bright magenta-pink flowers with a dark ‘eye’ and veins. The finely-cut leaves emerge golden-green, making a beautiful splash of light in the spring garden, gradually turning deep to mid-green, a lovely foil for the flowers. It has long stems and a vigorous, scrambling habit, up to 2’/60cm tall with a spread of up to 3’ 3”/1m, making it a brilliant filler plant and good ground-cover; it will also climb into roses.
Grow this geranium in a sheltered spot, in full sun or partial shade, in any reasonably fertile, well-drained soil. It flowers from July to October, and holds the RHS Award of Garden Merit.
This is a very long-flowering hybrid geranium with an airy, mound-forming habit, 18”/45cm tall, and pretty sprays of single white flowers with delicate magenta-purple veins borne between June and August.
The deeply cut leaves are deep green. It’s a very good plant for the front of a border, for ground-cover, and for the wilder garden, as the flowers, though plentiful, are not crowded; it looks particularly lovely with pink or deep pink roses, the deeply coloured veins reflecting their colour. This is a rhizomatous perennial, and can spread up to 5’/1.5m, but is easily divided. Grow in full sun or partial shade in any moist but well-drained soil.
An old but still hugely popular hybrid geranium of scrambling habit, Johnson’s Blue has single, lavender-blue, almost true-blue, flowers with darker veins and paler centres which show to perfection on long stems against the deeply-cut mid-green leaves that are faintly washed with silver. The flowers fade to a beautiful pearly grey.
Another rhizomatous perennial, it spreads to 2’/60cm, and is 1’/30cm tall; it makes excellent ground-cover, and a brilliant under-planting for old-fashioned roses. Grow in any moist but well-drained soil, in full sun or partial shade; it tolerates exposure. It flowers in early summer, but cutting back after the first flush will produce fresh new leaves and a few more flowers. A bee-magnet, and very good in a cottage-garden planting.