Cheerful geraniums

Sunday, 23 October 2011

Potted zonal Pelargonium cultivars in Assisi, Umbria, Italy

One of the most commonly seen plants during our trip to Italy was the geranium (properly known as Pelargonium, Zonal Hybrids). They were in pots everywhere: on balconies, windowsills and lined up beside doorways. They seem to grow very well in the dry Mediterranean climate; however, they are generally grown as annuals through summer, as the winter there is generally too cold for them to survive. Though we do get some foliage disease problems with them here in Sydney, they do grow pretty well here on the whole, and this spring, they seem to have been flowering madly.

Zonal Pelargonium in the garden of Anne Prescott in Sydney

These geraniums are one of those plants by which I can chart my gardening evolution. As a beginning gardener, I grew many from stolen cuttings, in na´ve wonderment of these ease of creating a new plant from a stalk and the simple joy of growing a flower. As I moved into my English garden phase, I threw them all out as vulgar, stinky horrors that had no place in my refined borders - I would only grow proper species Geranium types. Sadly, few of these proved suitable for my Sydney garden and nowadays the zonal Pelargonium are back in my garden, their decorative, rounded, fleshy leaves and brilliantly coloured flowers happily at home with other warm-climate plants. For hot-coloured gardens, red and orange-red flowered cultivars are perfect in pots or forming a wide shrubby mound (up to 60 cm if unpruned) amongst taller plants or an informal row along the front of a low fence. Fancy-leafed types with gold or blackish leaves, or dark-banded foliage are particularly effective with bright coloured flowers. There are also pretty pastels of pinks or white that fit in with cooler colour themes. There is even a soft pale yellow cultivar, called 'Creamery'. There are single, semi-double and double flower forms, as well as rosebud and star-shaped types. There are literally hundreds of named cultivars, though I have rarely known the names of any of mine.

Pelargonium Shady Lady

They are South African in origin, and flower almost all year round if trimmed back every so often through the year they will flower almost perpetually in our mild climate. Early to mid-spring is probably their absolute peak time, especially if they have been pruned by around two-thirds in early autumn to allow the development of a good plant structure. They should be tip pruned after the main pruning to develop a compact shape. These plants want sun and light, well-drained soil on the dry side, with good air circulation around them. I do, however, have a bright pink one called 'Shady Lady' that grows well in shade. In general, I have had better success growing them in the garden than in pots, as I found they got too leggy in containers. The miniature forms may be better suited to growing in a pot. If rust or other diseases strike in humid summers, I cut them back and they usually get over it. The 'Deacon' cultivars are said to be disease-resistant.

Ivy-leafed Pelargonium with Petrea volubilis in the garden of Anne Prescott in Sydney

Ivy-leafed geraniums (Pelargonium, Ivy-leafed Hybrids) are probably the easiest Pelargonium to grow in Sydney as they are not susceptible to diseases. They have very attractive glossy leaves and are scrambling or trailing plants with similar flowers to the zonal types, in colours of reds, white, pinks, mauves and purple. They can stand moister soil than the zonal geraniums and are excellent used to spill over retaining walls or banks, as a groundcover, as a subject for hanging baskets or to climb on wire fences. They don't need to be cut back as hard as the zonal types, or else they can be cut back by one-third at a time. They also benefit from tip pruning to create a dense form. They can flower almost all year round in our climate. This year I potted some of different colours together in a container on a sort of plinth and they cascaded down nicely. I also recently saw an amazing sight of a huge specimen of a crimson ivy geranium intertwined with the lilac-flowered climber Petrea volubilis, that stopped me in my tracks.

I also love regal geraniums (Pelargonium, Regal Hybrids), which flower for a shorter period from mid spring to early summer. The flowers are large and sumptuous and usually have a combination of colours and distinct blotches. They grow a bit taller than the zonal types, with attractive pleated leaves. They need hard pruning after flowering to keep them compact.

The best time for taking cuttings of any of these Pelargonium is in early autumn, when the plants are pruned. I find that it is best to replace them after a few years, as they can get woody with age. Don't overwater them, especially in January and February when it is humid. I give them just a general fertiliser when I do the rest of the garden. Mulching around them with cane mulch is said to help reduce the occurrence of diseases on the leaves.