25th November 2011
One of Mount Stewart’s iconic plants, the Mountain Cabbage Tree comes from New Zealand where it grows in cool, high rainfall conditions. Cordyline indivisa grows at higher altitudes than its more common relative, the ubiquitous Cordyline australis and is consequently marginally more hardy, surviving temperatures of around -16oC where Cordyline australis would be damaged.Discovered and named in 1786, it is not certain when Dracaena indivisa as it was originally named was introduced from New Zealand, but initially, it was grown under glass as a ‘stove plant’. The first plant which flowered outside was recorded at Tresco Abbey in 1895.
Young plants growing mostly in shade, with all year round moisture produce the most opulent foliage, but as the plants mature, the foliar vigour diminishes slightly. Cordyline indivisa will reach between 5 – 6m in around 20 years. Once it has attained its maximum height it will send out new heads from initials, usually at the base of the trunk. These will in turn develop, even as the original trunk diminishes and retrenches, eventually forming a cluster of less high trunks. These venerable specimens live to be over 100 years old.
Branching is formed naturally as a response to stresses like frost damage, drought, or physical damage. It can also be induced by trimming one side of the plants annual root system or if a plant is transplanted.
Once Cordyline indivisa has reached its full height at about 20 years old, it begins to set flowers. These are fully self compatible producing a complex structure called perigones, which in turn develop into purple/bluish berries. Flies or midges are thought to pollinate the flowers. The seed will germinate at 13oC under cool glass and once germinated, the seedlings must be kept cool and uniformly moist. Alternatively, new shoots root readily as soft wood cuttings, again kept cool and moist. Either way, Cordyline indivisa must not be kept under potted. Keep shifting the pots up as the young plants grow so as not to cramp the roots and plant out when about 450mm tall in a well prepared, humus rich nursery bed. When established and growing well, lift them carefully out in April/May to their final positions in the garden.