Cassia: Greenhouse Plants
C – cool, minimum of 7°C (45°F)
Well worth growing for their delicate, often downy foliage and bright canary yellow flowers. Cassia alata, the Candlestick Senna from Brazil, is most suitable for a small greenhouse as it will flower in a small pot at a height of 90 cm (3 ft). Flowers are borne in winter which is an added bonus.
C. artemisioides and C. helmsii are two Australian species which both excel themselves by being covered with a fine silky down. This has given the former the common name of Silver Cassia. Well worth trying is another Australian known as the Dense Cassia, C. sturtii. As well as being a compact 90 cm (3 ft), it bears a profusion of small fragrant flowers. My own favourites will always be C. corymbosa, an Argentinian species, and C. didymobotrya from East Africa which will bear its racemes of flowers in the first year of sowing and is often seen in Mediterranean gardens. Size need not be too much of a problem as these shrubby plants respond well to being pruned hard. It is always advisable to leave a spur of younger wood when making a cut. Propagation can be by shoottaken in late spring or by seed, which is best chipped before sowing and given a temperature of 21-24°C (70-75°F). I would favour a loam-based if temperatures are going to be low in winter as the compost will have to be kept on the dry side accordingly. There might be other benefits to growing these plants as they are the source of senna pods and are also gifted with many medicinal claims made for the seeds, pods, flowers and bark.