Coleus (Blumei-Hybrids)

Unlike the preceding genus, hybrids of the genus Coleus are models of easy and reliable cultivation and at the same time extremely ornamental plants. If they are provided with full sunlight then success is assured.

The more than 120 species of this genus are native to tropical Africa and Asia where they grow in places exposed to full sun, from sea level to mountain elevations in excess of 1,000 m (3,300 ft). The originally described species Coleus blumei, growing in gardens in Java, was probably already a hybrid and not a true botanical species. It was introduced into cultivation around 1850 and about 15 years later in England breeders raised the first cultivars, partly by crossing with other species, partly by selection of seedlings and their back crossing.

The plants are 30 to 80 cm (12 to 32 in) high with angular stems (becoming woody at the base) and leaves extremely variable in both shape and colour, generally softly hairy, often lobed or toothed on the margin. The flowers, which appear in late summer and autumn, have a white upper lip and usually a blue lower lip.

It is very difficult to recommend a particular cultivar for almost all are lovely. Two examples are ‘Otto Mann’ with brownish-red leaves edged with yellow and ‘Bien Venue’ with variegated red-yellow foliage, but you can choose what appeals to you most from the wide range offered by your nurseryman or from a catalogue.

In Europe mature plants generally do not overwinter well. It is best to take cuttings in summer and overwinter the young rooted plants at lower temperatures or else overwinter the cuttings in water. The soil should be acidic, best of all a mixture of peat, loam and sand. Feed, however, must be supplied liberally. Coleus also does extemely well in soilless cultivation (hydroponics).

15. November 2011 by Dave Pinkney
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