When, in 1631, the plant collector John Tradescant brought the first pelargonium to Britain he could not have imagined that three-and-a-half centuries later it would be the country’s most widely-grown plant. The demure species that he introduced has been transformed by plant breeders into thousands of different cultivars, with decorative leaves or scented foliage or, most valued of all, flamboyant, brightly coloured flowers.  There is now a pelargonium cultivar to suit every taste and every style of garden.

Prized for being easy to grow, long-flowering and floriferous, pelargoniums are reaching their peak now in window boxes, hanging baskets, containers and bedding schemes throughout the country and will be performing long after all other flowering plants have exhausted themselves.

Of course, to most gardeners and garden-centres these plants are not pelargoniums but geraniums . As long ago as 1901 the ‘Gardener’s Chronicle’ was bemoaning the fact that ‘the average gardener speaks of Geraniums when he means Pelargoniums’. True geraniums are hardy herbaceous perennials. Quite why the name geranium should persist is unclear, but it does and what botanists and horticulturalists know as pelargoniums are still called geraniums by most gardeners.

Our love-affair with pelargoniums has been long-lasting. As the plant hunters of the eighteenth and nineteenth centuries returned with new species from South Africa, home to over eighty-five percent of species pelargoniums, plant breeders produced a dizzying array of hybrids. For the Victorians, those with scented leaves were the most prized; the Edwardians valued the frilly flowers of regal pelargoniums; for the generation emerging from the drabness of the Second World War pelargoniums with overblown, gaudy flowers held most appeal. Such was their popularity during the 1950s that garden writer Beverley Nichols even suggested that there was something morally suspect about anybody who did not like them. “Never trust a man or woman who is not passionately devoted to pelargoniums”, he wrote.

Nichols’ sentiment is absurdly over the top but is right in suggesting that these are plants with such variety, charm and allure that they can’t fail to appeal to even the most reluctant gardener.

Angel Pelargoniums

When this group of pelargoniums was first bred in the early nineteenth century, they were sometimes known as ‘pansy-faced’ geraniums. Fortunately the name never caught on. Their flowers’ resemblance to pansies, though, is striking, with the top petals often being a darker colour to the lower ones, as they often are in pansies and violas.

When you see angel pelargoniums on display at flower shows they are always perfectly rounded domes that are smothered in small viola-like flowers. In the real world of the garden the plants are more unruly but if you feed them regularly during the summer they do produce a profusion of flowers. They look best grown in window boxes or containers, and a single pot of an angel pelargonium in full flower makes an impressive centre-piece on the patio table.

Typical of the group, and one I have found flowers all the way through October, is P. ‘Zoe’ which has two upper petals the colour of beetroot juice and three contrasting pale pink ones. Like the rest of the group, it grows into a dome about eighteen inches tall. For a variety that is reliably prolific choose P. ‘Imperial Butterfly’. The flowers are white with a maroon stain at the base of the petals and, as a bonus, the foliage has a slight citrus scent.

Ivy-leaved Pelargoniums

If you want pelargoniums to cascade from window boxes and hanging baskets or tumble over pots, this is the group for you. These are the plants that adorn windows throughout Europe, from Alpine chalets to Provençal farms. The best of the classic red-flowered cultivars, and the world’s most widely-grown pelargonium, is P. ‘Decora Imperial’. The bright-scarlet flowers are as vibrant under grey skies as they are in bright Mediterranean sunlight. Ivy-leaved pelargoniums are available in tones of red, pink and white but my own favourite is the deep-purple of the velvety flowers of P. ‘Tommy’.

Ivy-leaved pelargonium have fleshy, succulent-like leaves that help them retain moisture but in the harsh conditions of window boxes and hanging baskets they still need to be watered regularly. A weekly feed with liquid fertiliser and regular deadheading is very important to keep this group flowering until the end of summer.

Zonal Pelargoniums

Zonal pelargoniums, so called because their leaves usually have a coloured zone at the base, are upright, bushy plants that are most commonly seen in bedding schemes or on the benches of municipal greenhouses. Their large leaves hate to get wet and are prone to mildew, so grow them in the hottest, driest part of the garden. They thrive in pots and window boxes that are in full sun.  P. ‘Octavia Hill’ has intense scarlet flowers that stand up well to wind and rain.  The white-flowered hybrids tend to look dirty as they fade so choose a one such as  P. ‘Blanca’, whose sparkling white flowers last for weeks.

Many zonal pelargoniums have variegated foliage that is so eye-catching that they are difficult to place near other plants and are best grown alone. P. ‘Silver Delight’ has unusual white leaves that have a dark green centre. It is not a very vigorous plant but worth growing for the startling contrast between its carmine flowers and its silver foliage. P. ‘Mrs Pollock’, a cultivar from the 1850s, has green and maroon leaves that are edged in cream. Even when not in flower it certainly stands out. If you want something more restrained try P. ‘Distinction’, which has large rounded leaves that have a dark line penciled around their edge.

Most commercially available zonal pelargoniums are grown from seed and will last just one summer. Older varieties, and those grown from cuttings, are perennial and can be grown as houseplants through the winter or stored in a frost-free greenhouse until the following spring. In the warmth of the house they can become overgrown and leggy but they will quickly re-grow if you need to cut them back.

Species Pelargoniums

Not all pelargoniums have ostentatious flowers. If you are looking for plants that are sophisticated and understated then consider species pelargoniums, the wild ancestors of modern hybrids. Species pelargoniums have a delicacy and elegance that is irresistible, and are often as long-flowering and floriferous as their more gaudy descendants.

The first species pelargonium that I fell for was P. ionidflorum.  It is smothered with a cloud of magenta flowers from April to October, and only stops when it is cut down so that it can rest during the winter. Likewise, P. abrotanifolium will only stop flowering when cut back. This plant has sprawling stems of tightly-packed silvery leaves and white flowers that make it ideal for growing over the edge of containers.  Spreading stems are a feature of many species pelargoniums. I train the long, succulent-like stems of P. acetosum over 1m tall wicker structures to create a pyramid of bright pink flowers.

Where space is limited, consider growing a more compact species such as P. sidoides, with its heart-shaped, silvery-sheened grey leaves  and sprays of dark-purple, almost-black flowers. Despite its delicate demeanour this is a tough plant that is hardy in milder parts of Britain.

The attraction of some species lies not in the flowers but the scented leaves. P. tomentosum has grey, velvety leaves that smell of eucalyptus. It grows best in shade and will reach across to about a metre wide. At specialist nurseries you can find pelargoniums with the scent of lemon, almond, nutmeg and peppermint. Commonly found is P. ‘Attar of Roses’ whose flowers and leaves can be used to scent salads, jellies and ice-creams.

How to grow

Part of the appeal of pelargoniums is that they are so easy to grow. Few plants combine such low maintenance with high performance. You don’t need to be green-fingered, you don’t even need to be much of a gardener, to have beautiful, extravagant flowers all summer long. In containers, use a multi-purpose compost, preferably one that has a slow-release fertiliser incorporated. Water plants regularly − every day if they are growing in hanging baskets. To produce as many flowers as they do pelargoniums need lots of feeding. Every ten days or so water in a liquid fertiliser that has been specially formulated for pelargoniums or one that is high in potash (such as tomato feed).

Looking after pelargoniums is the sort of gardening you can do with a glass of wine in one hand. Regularly check over the plants and take off any spent flowers and dying leaves. If you don’t remove dead flowers your geraniums will look ugly and your plant will stop producing new flowers.