Borders display delicate finery
With their fluttering petals belying a tough nature, hardy geraniums are a gardener’s favourite, filling borders with cool hues
in a sunny cottage garden, the front of a herbaceous border is filled with bright pink, saucer-shaped flowers, held aloft on slender hairy stems. Bees flit between these glorious blooms, finding the small, simple, open flowers easy to pollinate. The flowers of hardy geraniums decorate many borders in summer, and it is easy to see why they are a ‘fail-safe’ plant for lots of gardeners. Tough enough to survive winter, strong enough to resist disease, they are free-flowering and shade-tolerant plants. Producing flowers which finesse a border with jewel-like blossom as spring merges into summer, they are in many ways a gardener’s dream.
Hardy geraniums have a delicate outward appearance that belies a steely nature. They can even be chopped to the ground with shears as a flush of flowers fades, only to regenerate and, in some cases, flower again, all within the same growing season.
There are many different commonly-grown hardy geranium species, which have subtle differences in flower colour, size and flowering time. Traditionally grown as edging or ground cover plants, there are also taller forms, which will mingle well in the middle of a border, and tiny types to grow in alpine displays.
Hardy geraniums are herbaceous perennial plants, dying down each winter before resurfacing in spring, although some varieties of Geranium macrorrhizum and Geranium x cantabrigiense can be evergreen. They typically flower in summer, although some begin to bloom at the end of spring. Other, sterile forms, such as ‘Rozanne’, which are bred to produce more flowers and do not set seed, can flower well into the autumn.
Hardy geraniums will grow well in any soil, provided it is not persistently waterlogged. If grown in light, free-draining soils, non-sterile types can self-seed freely, creating lots of new plants.
In pots, they can grow well if the compost is not too heavy. An equal parts mix of multi-purpose compost and John Innes compost is ideal.
British native
The UK climate is well suited to growing hardy geraniums; indeed Geranium sanguineum is a British native and grows here in the wild. This magenta-flowered species is also known as bloody cranesbill, due to the similarity of the plant’s fruit capsule to the beak of a crane, seen if the flowers are left on the plant to form fruits.
Hardy geranium flowers typically have five petals, arranged uniformly. The flowers are small, up to 1½in (4cm) wide, and appear in pairs or in clusters.
The early flowering forms of Geranium sylvaticum are
clustered together on upright stems, to make them more visible to early pollinating insects. The leaves of hardy geraniums can be very pretty in themselves, typically divided into five or seven sections. Some varieties, such as the pink-flowered ‘Max Frei’, produce their flowers on hairy stems, while others, such as the blue, stripy-flowered ‘Alan Mayes’ and Geranium x cantabrigiense, have hairy leaves. Some have beautifully coloured leaves in autumn, ‘Orion’ being particularly notable for its fiery red foliage at that time of year. Other varieties, such as ‘Ballerina’, have fine, silvery foliage. Although hardy geraniums are not particularly known for their fragrance, Geranium macrorrhizum has lemon-scented leaves.
Something for everyone
One person who knows more than most about the diverse nature of hardy geraniums is Vanessa Cook, who grows 112 different types at Stillingfleet Lodge Gardens and Nurseries, near York. It is the versatility of these plants that has prompted Vanessa to grow such a comprehensive range. “They are such useful plants, and there is a hardy geranium to suit many different conditions,” she explains. “Some of them will grow where no other plants will, such as in deep shade or dry shade underneath trees. Anybody can grow them, and slugs don’t eat them. They are a good choice.”
Hardy geraniums exude a charm that effortlessly adds some delicate finery to many different garden styles, although Vanessa says that a wildlife garden suits these plants very well. “They are especially good if you don’t want a particularly tidy garden, and as they don’t get diseases or are troubled by pests, there is less need to resort to chemicals. They are also fantastic plants for bumblebees.”
Flowers aplenty
Another reason for the enduring popularity of hardy geraniums is their long flowering season. The wealth of varieties available means there will be a hardy geranium in flower from early summer until the first frosts. “Most of them are really easy to grow; it’s really just a case of choosing the colour and the size you want, and whether or not you want to grow them in shade or sun,” explains Vanessa. Her top choice for shade is Geranium nodosum. All varieties of this species, such as ‘Clos du Coudray’, which has dark purple flowers, beautifully edged with white, and glossy dark green leaves, grow well, even in dense shade, as well as in dry conditions. They flower all summer, growing to 18in (45cm) tall, and will seed around well too.
The range of colours available in hardy geraniums sit largely, but not exclusively, on the cool side of the spectrum, and the first hardy geraniums of the year to bloom are the varieties of Geranium sylvaticum, which begin to flower from May. There is
“He shall know the field flowers, lady’s bedstraw and lady’s slipper, purple mallow, blue chicory and the cranesbills – dusky, bloody, and blue as heaven” Robert Byron, ‘All These I Learnt’
a crisp white ‘Album’, while ‘Amy Doncaster’ has deep blue flowers with a white eye. Varieties of this species are upright growers that make for a fairly tall, slender plant and are not too vigorous. For an azure blue, G. sylvaticum ‘Mayflower’ provides a show of vivid lilac on a tall plant. Growing to approximately 3ft (1m) in height, this variety is useful for filling gaps in the middle of a border and will flower during late spring and early summer.
There are also intriguing variations in foliage within hardy geraniums. The leaves can develop a reddish-brown colour as they age, to add some autumnal shades to the garden. Cerise-flowered ‘Crystal Rose’ has this characteristic, and its foliage is scented too. Mauve-flowered Geranium phaeum ‘Margaret Wilson’ is a variegated one. It has yellowy-green leaves with pale streaks running through them, while Geranium maculatum ‘Elizabeth Ann’ has dark reddish-brown leaves, which show off its pale pink flowers.
Vanessa suggests hardy geranium ‘Patricia’ as the variety which flowers for the longest period, with flowers from May to September on a plant 24in (60cm) tall. It is a hybrid of the species Geranium endressii and G. psilostemon. This is a sterile variety, so it does not set seed, instead, putting its energy into producing more blooms.
“It flowers for longer than any variety that I know of,” says Vanessa. Many hardy geraniums will produce a second flush of blooms if they are chopped down when the flowers have faded in summer, although the sylvaticums are an exception to this rule and are unlikely to do so. Cutting the whole plant back to just above ground level, however, will produce a new burst of young leaves, which will give garden borders a fresh, verdant lift in the second half of summer.
The enduring appeal of hardy geraniums is enhanced by their varying in vigour from species to species, meaning that there is one of sufficient stature for a range of garden scenarios. A very free-flowering group is the sun-loving G. cinereum Jolly Jewels series, which only grow to 4in (10cm) tall, but flower for 3-4 months in full sun. These are Vanessa’s top choice for growing in an alpine trough or a rockery, as they produce a neat, cushion-shaped plant. The Jolly Jewels series of varieties have been bred in the Netherlands and include a range of warmer coloured flowers, with red-, purple- and salmon-hued forms.
If a more vigorous, substantial plant is desired to cover a large area, then the polar opposite of the Jolly Jewels is another sterile choice: the violet-blue-flowered ‘Rozanne’. This grows to up to 3ft (1m) in height and spread. “It has a lovely big flower and can make a huge plant. It is best to cut it down after the first flush of flowers though, to control its size,” advises Vanessa.
While ‘Rozanne’ is a widely grown and often recommended hardy geranium, Vanessa chooses Geranium wallachianum as the most underrated. “There is an amazing colour range, and they flower from August to September, when many people have started to forget about their gardens. They are really wonderful plants, which will sprawl in between others. I think ‘Crystal Lake’ is one of the best, with beautiful pale lilac flowers which have intricate purple veins.”
But, whether in the joy of the moment when spring gloriously turns to summer, or the bittersweet days when summer wistfully fades away, there will be a hardy geranium out there to bring colour to the garden.