MONTY DON

If you want flowers and fragrance from your container plants all summer long, says Monty Don, plump for pelargoniums...

Looking for the perfect pot plant? Pelargoniums will provide flowers and fragrance for months, says our gardening expert

Pelargoniums – tender and shrubby, happiest in blazing sun and dry conditions – are often wrongly called geraniums. In fact, our native cranesbill, the hardy geranium, is very different: it’s herbaceous, can grow in full sun or dry shade and is able to cope with heat just as well as cool, damp conditions.

Pelargoniums originate mainly from

South Africa, with 125 species from around the Cape alone. I’ve made three trips to the Fynbos – a belt of shrubland around Cape Town – to see them in their natural environment, where they can make large shrubs flaunting pink flowers. To get the best from a pelargonium it’s useful to remember their natural habitat, the dry, exposed terrain of the Fynbos. It’s better to water them too little than too much, allowing the compost to dry out completely between each soak.

There are over 200 species of pelargonium and six types of hybrid, each producing a raft of variations on quite a tightly defined theme. The ‘zonal’ ones are the familiar hothouse bedding plants with leaves like opened fans, often with a chocolate rim or centre. The flowers are on long stalks and massed into clusters.

‘ Uniques’ are shrubby plants with masses of small flowers and foliage that gives out a scent when crushed. They need protection when summer is over but they flower for a long time. ‘Regals’ can have some of the best and richest colours – ‘Springfield Black’ is a deep burgundy and ‘Dark Venus’ is a superb plum colour. They need more watering than other pelargoniums and a warmer minimum temperature in winter.

Ivy-leafed ones derive from Pelargonium peltatum. While they often have masses of small flowers, their real virtue is that they trail beautifully and therefore are good for hanging baskets, window boxes and larger pots. Angel pelargoniums were bred from P. crispum. Their flowers are often ordinary but they’re popular because they bloom all summer.

Quite a few of the species have scented leaves and are worth growing for this alone, regardless of their flowers. There’s the cream variegated ‘Lady Plymouth’, which is touched with the scent of roses; P. graveolens has a delicious orangey fragrance; P. tomentosum is pepperminty; and ‘Mabel Grey’, the most famous of the lot, is lemon-scented. All these should be watered with rainwater rather than tap.

Species pelargoniums, like all species plants, tend to be tougher, less showy and more interesting in their detail than the hybrids bred from them. For example, P. sidoides has small glaucous leaves and tiny flowers carried on long wispy stems, but these flowers are the colour of the deepest, plummiest wine, and this pelargonium has a charm that few others with much more volume in their display could ever muster.

Whatever kind of pelargonium you’re growing, the more constricted its roots the more profuse its flowering will be. However, the bigger the plant, the more spectacular the display. To reach a compromise between a vigorous, growing plant that has limited flowers and one with limited potential for growth but a spectacular floral display, you can repeatedly repot it into a slightly larger container before it starts to flower so it will continue to grow vigorously until its roots become constricted. Then, when it’s as big as you want it, leave it in the pot it’s in, and as the roots become constricted it will flower profusely.

On the other hand, if you have a pelargonium that’s become too big and unwieldy, it can always be cut cleanly across about a foot from the base. It will regrow vigorously until it reaches a manageable size.

Monty with some of his pelargoniums