Advanced Gardening
Dendrobium or ‘bamboo’ orchids make great indoor plants, and with the right know-how you can propagate your own by following Steve and Val Bradley’s advice
THERE was a time when the only place to see orchids was in a botanic collection because they were expensive treasures, brought back to this country from around the world by traders and collectors. Originally, wealthy merchants would use them to show off to their friends (and rivals) to prove just how rich they were, not just acquiring these exotic plants from all over the world, but also affording the conditions to keep them alive here.
Gradually, these collections were lost or given to specialist centres like botanic gardens, where there were facilities designed to provide warmth and humidity, and the growers who knew how to tend their charges.
Dramatic change in the 1970s
The introduction of micropropagation in the 1970s changed plant growing, because by using just a few cells, grown in special gels, it became possible to grow new plants by the thousand at a fraction of the time and cost of traditional methods. These days, orchids are hugely popular indoor plants and the number of species available is increasing all the time.
Dendrobium nobile
There are around 1,800 species of Dendrobium orchids, making them one of the largest of all the orchid groups. In the UK, we usually see the white or purple-tinted Dendrobium nobile
(‘bamboo orchids’) for sale in full bloom with one or sometimes two stems of attractive honey-scented flowers.
Originating from South and SouthEast Asia, they make good indoor plants and are generally happy in similar conditions to moth orchids (Phalaenopsis). They need good light, but not bright sun, and are happy in a bright east or west-facing window. Too much sun can cause scorching of the leaves. They also like humidity, making them good for a bathroom or kitchen.
Lifecycle of flowers
The flowers last several weeks before dying off, leaving the segmented stem, which looks a bit like bamboo and gives rise to the common name. New stems arise at the base, usually one or two a year, which will grow up and flower later. Resist the urge to repot the plant too often as they flower better if slightly cramped. Keep the plant well watered and fed throughout the spring-autumn season, but ease off in winter to keep it barely moist. Older plants can be divided once they have at least four stems, by cutting through the roots with a clean, sharp knife and then potting the separate pieces into smaller pots in fresh orchid compost.
New plants or keikis
Old flowered stems should not be cut off unless they die back, as they will often rebloom or form small new plants called keikis (Hawaiian for ‘baby’), that grow on the stem itself and will gradually form their own roots. This is an easier means of propagation than division because there is no risk to the roots of the main plant. Once you can see a root system developing on the little keiki, carefully cut it from the stem and pot it into fresh free-draining orchid compost.
Occasionally, these keikis will fall away of their own accord and can be potted separately. Use a cane to provide stability while the roots of the little plant get used to their new environment. Water enough to keep the plant moist, but never wet, and mist to maintain high levels of humidity.