Ten years back only the clueless grew coleus. They were gaudy relics from Grandmother's generation, but now coleus are back and teetering on the cutting edge. Why the change? They have been perfected. New varieties have colours that intensify in sun, but can also thrive in shade. In fact, because of their low light demands, coleus can also be used as house plants.
The 'Wizard' Series is an excellent example of the new developments, it is the best seed raised strain for bedding and containers. The compact plants are durable and hardy to around 10°C (50°F). With colourful, medium-size leaves and a base-branching growth, they grow naturally close-to-the-ground and never need pinching to reach a bushy, symmetrical, compact form.
Growing 25 to 30cm (10 to 12in) tall, the heart-shaped leaves appear in vivid shades that all reach the same size at the same time.
Coleus are one of the easiest and most satisfying plants to grow, showing their first colours in as little as two weeks and keeping their hues right through the worst summer heat and humidity. They make wonderful plants for the summer border and are ideal for large containers or grown as a house plant, they do best in part to full shade and moist, well-drained soil enriched with organics. They make invaluable summer fillers for sunny borders when an earlier planting has failed, fairly vigorous they will quickly fill a gap with real style. They work well in most situations. In containers or the border, they accentuate the hues amongst annuals or perennials. They excel when used in combination with other shade lovers.
From the brilliant apricot-bronze Sunset, to red-veined maroon Velvet Red, each of the 'Wizard' varieties is a distinctive work of art.
The Wizard Series of colourways are:
- Jade - Clear ivory heart-shaped leaves, edged with a jade green margin, they work well in most situations.
- Velvet Red - One of the most popular colourways, plants with rich, velvety deep red leaves. Good in full sun
- Sunset - Vivid shades of apricot-bronze. Excellent in full sun, they make distinctive container plants and combine well with the warmer colours in the border.
- Coral Sunrise - Beautiful coral pink heart-shaped leaves have neatly serrated edges, with shades of olive and intense bright green margins.
- Scarlet - Rich bronze-red, heart-shaped leaves, each with delicate pale green serrated edges. Excellent in full sun.
- Pastel - The most delicate colourway from the series. Coral pink leaves, marbled with deep bronze and edged green.
- Mosaic - The most recent introduction to the series, this shade lover features bright green foliage with splashes of burgundy red and cream. While it is good for full sun it shows the most intense colour in full shade.
- Wizard Mixed - An exotic mixture of the Wizard varieties. Especially for gardeners who like surprises!
Sow all year round for pot plant. For the garden, sow 10 to 12 weeks before the last expected frost, they will then be well developed when it is time to plant them outdoors.
Sow seeds onto a layer of moistened, sterile potting soil in a shallow tray, do not cover as they need light to germinate. Cover with glass or plastic to retain moisture, until the seeds have germinated. Place in a warm (21°C/ 0°F), bright (not full sun) place.
When the seedlings are large enough to handle, transplant into individual pots. Seedlings should always be held by a leaf, never by the stem.
When pricking out coleuses note that larger and stronger plants often have poorer quality foliage. When all danger of frost is past the plants may be set out in the garden. Plant them 30cm (12in) apart in rich, moist, well-drained soil.
Young leaves have to be protected against low temperatures and full sun. The leaves of the plants may get burned at high light intensity. Avoid drought stress, but do not overwater, the lower the growing temperature, the lower the water supply should be.
Fertilise with a diluted (50% mix) liquid fertiliser, too much feeding with high nitrogen fertilisers, encourages soft growth and poorer quality foliage. Coleus is very durable, so you can cut your plant back severely if needed (almost back to the soil level).
Leaves and flowers develop at the same time. Remove the flowers and pinch out new shoots for a bushier plant. To extend the lush colour into autumn, remove any stray flower spikes that emerge, as they take energy away from maintaining the gorgeous foliage, and the flowers are not particularly attractive.
Coleus should be kept at a 15 to 20°C (60-70°F) over winter. They will survive down to 10°C (50°F), and have been known to survive at 4°C (40°F) but only if kept dry, losses to rot and fungal diseases are high if the plants are allowed to get cold and damp.
Best in pots as house plants, or in the warmer conservatory, coleus can also be grown in containers or window boxes alongside other temporary summer planting. They can also look good bedded out with salvias, rudbeckias, gaillardias and other late-summer flowers in the red-yellow end of the spectrum in warm borders.
The intensity of light which the plant receives will have a direct bearing on the intensity of the foliage colouring. Some varieties of coleus may produce their best colour in light shade, while others look best in bright lighting.
Coleus eventually produces woody stems and can be trained as standards. To do this, pinch out side-shoots and support the stem with a 3ft cane. When the plant reaches the desired height, pinch out the top shoot and keep removing lead shoots.
The roots of coleus are known from ancient times, where it served as a stand in for Salvia divinorum, in shamanistic rituals. Not much research has been done on the psychoactive chemicals within the plant. The effects resemble those of psilocybin, which is found in psilocybian mushrooms.
Two species were in cultivation here by the 1860s, C. verschaftelti and C. blumei, and the first coloured-leaf variety appeared at a Royal Horticultural Society show in June 1861, introduced by William Bull, a nurseryman of King's Road, Chelsea. Seven years later the RHS organised a promotional auction of new hybrids. One plant fetched 59 guineas, expensive now, but in those days was an enormous sum.
Meanwhile Bull had bred about 150 varieties, of which he was marketing the best 18, cannily timing new releases to coincide with mentions of the plant in the gardening press. The breeding and propagation of sports was so frenetic that Gardener's Chronicle of 1869 dubbed it "coleus fever". Varieties have changed little since then and we're still working with essentially Victorian material.
Several years ago, the powers that be changed the name to Solenostemon but in a blatant act of taxonomic defiance, we refuse to call them anything but Coleus.
Ray Rogers - Coleus: Rainbow Foliage for Containers and Gardens:
This book is the most comprehensive work ever written on coleus, covering over 225 varieties with almost 400 spectacular photographs. The last half of the book (almost 100 pages) is an encyclopedia of the various coleus cultivars. The categories are in themselves quite informative. First there are the trailing ones (great for hanging baskets and container gardening), then they are broken down by leaf shape and size (elongate, fingered, duckfoot, twisted, and little), and then it starts to get really interesting. The next and largest section is “Cultivars by colour or pattern”. There are 26 sub-categories in this section! Red with green edge, Red with orange edge, Red-Orange with yellow edge, Yellow with red flecks or patterns, Green with red edge, and on and on. The last section is called Unique Cultivars and these are the ones that defy categorisation. The pros and cons of each variety are discussed in detail.
The chapter on Coleus in the Garden is just incredible. It’s mostly pictures with detailed captions, but wow, what pictures. The colour, shape and texture combinations with other plants is positively psychedelic. And when coleus are combined with other tropicals (such as croton) it’s as good as it gets! Coleus are after all from Java.
The photo captions are remarkably thorough, sometimes explaining what’s wrong and how to avoid it. Rogers lets us know that the same cultivar can have lots of different names, and lets us know what they all are. He tells us what to expect from the different seed mixes. If you weren’t a big coleus fan when you opened the book, you will be by the time you close it.
Timber Press, Portland, Oregon, www.timberpress.com, 2008.
978-0-88192-865-5, 288 pages, colour photographs, hardback.
- Additional Information
Packet Size 25 Seeds Family Lamiaceae Genus Solenostemon Species scutellarioides Cultivar Wizard Series Common Name Painted Nettle, Flame Nettle Hardiness Tender Perennial often used as an Annual Flowers Very large blooms, 9 to 10cm (3½ to 4in) wide. Natural Flower Time Summer through to first frosts Height 25 to 30cm (10 to12in) Spread 25 to 30cm (10 to 12in) Position Full sun or partial shade Soil Rich, moist, well-drained soil Time to Sow Sow all year round for indoor plants or sow in late spring for outdoor plants