Treat them mean...

Constrict their roots, don’t feed them, water them minimally, and pelargoniums will flower all summer

Pelargoniums originate mainly from South Africa, where I’ve seen them growing in the Fynbos – a belt of heathland around Cape Town – as great shrubs flaunting pink flowers. When growing them, as with any plant, it is useful to remember their natural habitat – in this case bare, dry, rocky terrain.

There are six types of pelargoniums. The zonal ones have leaves like opened fans, often with a chocolate rim or centre. They hate getting wet and can suffer from mould, black leg and rust, but they have a wonderfully exotic aura. Best grown at the base of a sunny, south-facing wall, they’re either propagated from seed, in which case they’re treated as bedding annuals, or from cuttings, which produce larger flowers and will survive as perennials.

Unique pelargoniums are shrubby with masses of small flowers and foliage that’s scented when crushed. They mostly flower for a long time.

Regal types, meanwhile, flower in early summer, with overlapping petals that almost obscure the foliage. They can have some of the best and richest colours of all pelargoniums, with ‘Springfield Black’ a deep burgundy and ‘Dark Venus’ a superb plum colour. They do need more watering than other pelargoniums and a warmer minimum temperature in winter if they are to survive and thrive.

Ivy-leaved ones often have masses of small flowers, but their real virtue is that they trail and so are good for hanging baskets, window boxes and cascading down walls.

Species pelargoniums tend to be tougher, less showy and often more interesting than hybrids that have been bred from them. P. ‘Splendide’ has viola-like raspberriesand-cream flowers. Quite a few of the species have scented leaves. There’s the cream variegated ‘Lady Plymouth’, which comes up smelling of roses, P. graveolens, which has a delicious orangey fragrance, P. odoratissimum, which smells of apple, P. fragrans, which exudes astonishing pine freshness (although some people swear it smells of nutmeg), P. tomentosum, which is pepperminty, and ‘Mabel Grey’, which is lemon-scented. All these should be watered with rain water rather than tap water.

Finally there are angel pelargoniums. I have a small P. crispum and it is modestly handsome, the leaves growing tightly to the upright stems. But the angels are not terribly typical of this, being looser and bushier and having the main advantage of flowering continuously all summer. There is one very special one called ‘Sarah Don’, bred by Roger Jones at Oakleigh Nurseries in Hampshire and named in honour of my wife. It has a golden variegated leaf and magenta and paler pink flower and is, like its namesake, magnificent.

In general the harder a pelargonium is treated, the better it will flower, as they only start to flower when the roots become constricted. So I keep them in smallish terracotta pots and do not feed them at all. You can, however, make any plant grow rapidly by repeatedly repotting it into a slightly larger container before it starts to flower. If you keep doing this, the plant will continue to grow vigorously until its roots become constricted. Then, when it is as big as you want it, leave it in the pot it is in and as the roots become increasingly constricted it’ll

flower profusely. If your pelargonium is too unwieldy, cut it cleanly across about 30cm from the base and it will regrow vigorously. Most problems with pelargoniums are due to overwatering. They need only minimal water, especially over winter. Let the plants dry out completely between each watering. If the leaves start to become tinged with orange or yellow, reduce their water intake for a while.

Pelargoniums including (inset above) ‘Sarah Don’ and (inset below) ‘Splendide’