GROWING GERANIUMS?
ONE of the constant frustrations of dealing with plants from all over the world is the myriad of common names that can apply to a single species, and conversely, the plethora of species that can have the same common name.
Some examples of the above conundrums are the large numbers of plants with the word “rose” in their common name.
Here’s a few: Black rose (Aeonium ‘Zwartkop’), Sturt’s Desert Rose (Gossypium sturtianum), the Lenten Rose (Helleborus orientalis) and the Rose of Sharon (Hibiscus syriacus).
A great example of a single species having many common names, quite dependant on the region in which it grows, is Echium plantagineum, a pasture weed, with the common names of Salvation Jane, Patterson’s Curse, Purple Viper’s Bugloss, blue weed, Southern Bluebell, and Riverina Bluebell. Confusing, eh?
And, so, we come to the term “geranium”, a common name most Australian gardeners use to describe the range of heat-loving, evergreen, perennial plants from South Africa, which are actually part of the genus Pelargonium.
Interestingly, the true Geranium is not a Pelargonium, but a genus of plants in the same family, Geraniaceae, most being found around the Mediterranean region, with a number scattered throughout the temperate climate zones of the world.
As the climate has been rather warm of late, why don’t we take a look at Pelargoniums this week, as they would have been quite tolerant of the sizzling summers of the last few years, and worth considering in any garden where beds are exposed to full sun and heat.
Arguably one of the world’s most commonly grown flowering pot plants, and a favourite garden plant too, the zonal pelargonium (Pelargonium x hortorum) has been in cultivation since the late 1700s.
The term “zonal” refers to a dark, horseshoe-shaped marking on the kidneyshaped leaves of nearly all these interspecific hybrids.
They flower above the foliage in the warmer months, sporting such colours as white, pink, red, purple, mauve, and even orange.
Zonals prefer sunny, frost-free spots in the garden, where they’ll bloom nearly all yearround.
Their soft, downy leaves can be badly affected by rust if constantly wet or subject to long periods of high humidity, and the ravenous budworm can damage new growth in the warmer months.
There are hundreds of cultivars of this popular plant, with one of the most popular selections being the ‘Maverick’ range, with 13 colours from which to choose, including ‘Salmon’, ‘Quicksilver’, ‘Orange’ and ‘Scarlet
Picotee’.
There are also many “fancy-leaved” zonals with variegated foliage, some with quite striking patterns.
I have ‘Madame Salleron’ in my garden (green/cream variegation), happily growing in part shade under a Japanese maple.
The ivy-leaved pelargonium, P. peltatum, is a sprawling, clambering species which produces long-lasting displays of blooms from spring to autumn.
They are more or less disease free, coping with humidity, and untroubled by rust and caterpillars, unlike their cousin P. x hortorum.
If overwatered they can develop a condition called oedema, where the leaf develops pustules which burst and turn corky after drying out.
They can be trained up trellises and make ideal hanging basket specimens, flowering in colours from white, through pink and magenta to red.
An exciting range of hybrids between the zonal and ivy-leaved pelargoniums have been on the market for a number of years.
They show good disease resistance and flower profusely above tightly packed low, sometimes slightly trailing foliage.
They are definitely worth trying in the garden or in pots.
Look for the “Big” range (Calliope varieties) such as ‘Big Splash’, ‘Big Red’, ‘Big Burgundy’ and ‘Big Pink Splash’.
Scented-leaved pelargoniums are one of those old-fashioned plants that you’d typically find in a cottage or kitchen garden.
Many have tiny to palm-sized leaves which are ruffled, toothed, deeply lobed, fern-like or deeply divided, all of which will release a
scent when brushed or bruised.
Some of the more common scents are peppermint, apple, lemon, rose, orange, spice and nutmeg.
In almost all cases the flowers are not usually the main feature, like many herbs.
They prefer full sun, and a soil that has not been over-fertilised, as high nitrogen levels will produce soft leaf growth with reduced scent.
In the 1990s, a variety of scented-leaved pelargonium was promoted as a mosquitorepellent “Mozzie Buster” plant, which was later proven to be untrue.
There are a few native Australian pelargoniums worthy of garden cultivation.
One of these is P. australe, found from Tasmania to New South Wales, an herbaceous plant that produces small, whitestreaked flowers with red markings above the soft and hairy mid green foliage.
Another low-growing pelargonium, this one with velvety grey-green kidney-shaped leaves, is P. reniforme (South Africa).
It’s a great border or basket plant, producing long sprays of single purplemagenta blooms in the warmer months.
It’s also pretty easy to strike from parts of its tuberous roots.
All pelargoniums will need to be pruned after flowering to produce more compact, leafy plants, and many don’t need lots of fertiliser.
Some may only survive one or two seasons in the garden, usually succumbing to long, humid or wet periods of weather.
Nonetheless, there are few flowering plants that will handle hot, full-sun positions like most of these beauties do.