Pelargonium (Geraniums)
Pelargoniums have an old fashioned charm, yet new cultivars are being bred all the time (they're among the world's most popular ornamental plants). There are hundreds to try, including some with striking coloured foliage.
With watering restrictions hitting hard in this state, maybe it's time for the heat- and drought-tolerant garden "geranium" to make a comeback in Queensland, especially among those gardeners wanting flowers and a fairly traditional style of garden.
Geranium or Pelargonium?
Local gardeners, when talking about "Geraniums", are almost certainly referring to members of the genus Pelargonium. Long ago they were included in Geranium, but today the pelargoniums have their own genus. One of the distinguishing features is that all the petals of the Geranium flower are similar and are arranged evenly around the centre. On the other hand, the individual Pelargonium flower has an uneven distribution of petals, although this may be a little difficult to observe in some garden cutivars.
Ornamental Geranium are popular among cool climate climate gardeners. On this page, however, the discussion will be about Pelargonium species and hybrids, which will be referred to simply as "pelargoniums".
Types of Pelargonium
Although there are some Australian native species, most wild species come from the African region. Collectors and hybridisers may be interested in some of the these. See the links at the bottom of this page for more detailed information on the Geraniaceae family.
Garden pelagoniums have arisen from prolonged selection and hybridisation. The types most commonly cultivated in Queensland may be divided into three main groups: the shrubby "zonals", the trailing "ivy leaved" and the "scented".
Zonal Pelargoniums
This is the group which is probably most familiar to Queensland gardeners. "Zonal" refers to the band of colour the leaves often exhibit. The centuries that pelargoniums have been in cultivation have given rise to many hybrids, often of uncerain parentage, hence the botanical nomenclature of P. x hortorum for the zonals, simply indicating that they are hybrids of horticultural origin.
Compared to many other flowers, they are relatively easy-care plants. Nevertheless a little attention, including judicious use of water and fertiliser, will naturally give the best results.
The somewhat fleshy stems and leaves give a hint of their to their drought tolerance. This makes them well adapted to growing in pots, providing drainage is good and they are not overwatered. (Some wild species have very succulent stems or tubers.)
They grow outdoors in Brisbane all year round, but gardeners in cold climates protect them indoors during the winters, as whole plants or as rooted cuttings. They can also used be used as bedding plants for temporary displays.
Scented Leaf Pelargoniums
This group is grown mainly for the aroma the leaves emit when brushed or crushed. An range of frangrances are represented in different species and cultivars. The overall growth form in most scenteds is somewhat like the zonals, but the leaves and flowers are usually much less flamboyant in appearence. They make a wonderful addition to a herb garden, cottage style garden, a garden for children or for the visually impaired (the leaves can have interesting tactile properties, too).
Ivy leaf Pelargoniums
These have a distinctive leaf, similar in shape to that of an ivy. The stems are thin with a trailing habit, making them well suited to hanging baskets, large containers or retaining walls that they can cascade over, or even trained up a trellis or similar support.
Other types
Another major group is the Regals (also called Martha Washingtons). They are probably best avoided by the inexperienced grower, especially in the warmer parts of Queensland because of their requirement for cool conditions.
Some hybrids are available that are intermediate between groups, e.g. between Ivy and Zonal. As breeders continue to experiment with crosses between these and other pelargoniums, new classes of plants have emerged such as the "Staphs" and "Deacons" with particular characteristics of plant habit or flower form. Browse the catalogue of a specialist pelagonium nursery and you'll find an amazing diversity of foliage and flower colours and forms.
More Links
The following are for general information, research and ideas - some species or cultivars referred to in links may be unavailable in Australia or unsuitable for Queensland conditions
Queensland
Rest of Australia
Geelong Botanic Gardens contains an Ornamental Plant Conservation Association of Australia collection of Pelargonium
Geraniums
(part of The Beckingham-Steele website, Western Australia). Pictures and tips, plus some history of these plants in Australia.
International
Basic cultural information:
Geranium Clemson University, South Carolina, USA
Geraniums Virginia Polytechnic Institute and State University
Growing Geraniums Backyard Gardener column, May 25, 2005. Arizona Cooperative Extension, University of Arizona
Botany, taxonomy, and other information for enthusiasts:
PlantZAfrica.com Look under "Plants of SA" for information on several South African species, including some of the parents of common horticultural hybrids
Pelargonium tricolor Reproduced from Veld & Flora, Botanical Society of South Africa, at the PlantZAfrica website
Who says they are boring?
South African Pelargoniums. Reproduced from Veld & Flora, Botanical Society of South Africa, at the PlantZAfrica website
Pelargonium at the Pacific Bulb Society (Information on some tuberous species)
Possible Misspellings: Pelagonium, Pelagoinum, Pelargoium, Pellagonium, Pellargonium
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