In my current preoccupation with the heat and dryness of this incredible summer, I have been taking note of what people tell me about what is surviving the onslaught in Sydney gardens. Amongst the stalwarts, coleus plants are often being mentioned: they seem to thrive in this current weather! Last week, when I happened to be catching a quick bite to eat at a seaside cafe on Sydney's northern beaches, I saw a gardener planting out the huge containers (including some old dinghies!) that decorate this place, with some really stunning-looking coleus cultivars. I just felt I had to devote a blog to these amazing plants, which really seem to be able to take all that is thrown at them at this time of year.
Hailing from South-east Asia, coleus were known botanically as Solenostemon scutellarioides but recently reclassified as Plectranthus scutellarioides - but neither of these names seem to have really caught on amongst us hands-on gardeners, as far as I can tell! I remember them being grown in my parents' garden in the 1970s and '80s, and they have become fashionable again in recent years. They offer some of the best foliage that Sydney gardeners could possibly hope for, with their huge array of colours and forms. They are so very useful for bringing colour to shaded spots, though many grow well in sunny places too, extending their usefulness. Their multicoloured leaves have endless potential for creating 'colour echoes' with nearby flowers or foliage of the same hues. They work very well with 'semi-tropical'-style plants such as Colocasia, Odontonema, Cuphea, Dahlia and bromeliads.
The leaves may have contrasting coloured edges, freckles, bands or other markings; leaf shapes vary from long and pointed to rounded or finger-like, or even what is termed 'duck-foot' by coleus fanciers. Almost every imaginable colour can be found in some coleus or other! I particularly like those that have dark markings on the leaves. I don't know the names of any of my coleus plants, but there are apparently many named cultivars. Heights can vary but they are usually around 60 cm tall. Some forms have a trailing habit. The best way to acquire good doers is as cuttings from other gardeners.
Coleus grow very easily from cuttings and will even sprout roots in a glass of water, being an ideal subject for beginning propagators! Recently, I was given a gorgeous posy made entirely of different coloured coleus; all took root in the vase and I now am growing them on in pots! I usually take cuttings of my favourite ones each autumn, as a precaution against losing them in a very cold winter: though some do survive winter in my garden, many succumb to the cold and those that do survive take a while to recover. I don't cut these back whilst the weather is still cold, as that can kill them - I wait till early September before cutting them back and fertilising them with a general purpose food. Coleus can be grown from seed, and some gardeners report them coming up by themselves by self-seeding in the garden, although I have never had this happen.
Coleus grow best in a well-drained soil with adequate moisture and regular liquid feeding, though they will still survive given less-than-optimal conditions. In the warmer months, pinch out the growing tips regularly to encourage a well-branched plant, and remove any flower stems that develop, as these make the plant look lanky. They can be subject to the annoying flea beetle, which disfigure the leaves: my preferred method of dealing with these menaces is to flick them into a jar of soapy water: painstaking but effective! Coleus can be grown in containers or hanging baskets. It is even possible to train a standardised coleus! For lots of information and ideas on coleus, I can recommend the book Coleus: Rainbow foliage for containers and gardens by Ray Rogers.
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