Cordyline australis (Cabbage Tree)
Terribly well known spiky exotic from New Zealand. Tough as old boots but not very frost hardy – withstanding -10°c without too much damage. You can wrap the heads with hessian or fleece if the forecast says icy blasts but it’s no fun, I can tell you. Cold is unlikely to be a problem in the centre of very large cities or within a few miles of the coast. Although they’ll grow in any soil, they undoubtedly look at their best if they have lots of light and space. The heads look thicker and healthier and the plant takes on a good shape. They form a trunk and will often flower when the trunk’s about 8 – 10ft tall. Where there’s a flower, it will branch and over many years, these trees will become multi-headed as a result of all the flowers. Getting up a ladder and removing old leaves and old flowers is a bit of sport. Try it. All done with a pair of secateurs and the results are gratifying if you like a bit of tidiness in the garden.
Plants are sometimes afflicted with yellow rust spots on the older leaves – a disease that normally only affects wheat. Best to remove and burn the leaves although a fungicide can be used to spray the rust. The fungicide will only stop the disease spreading, not make the rust go away. More importantly, we find that it’s only plants in pots that are susceptible to this. Once they’re in the ground, they’re so much happier that the problem often vanishes. A further reminder of how much happier plants are where they belong (the ground), as opposed to where they don’t belong (a pot).
We’ve noticed that on some plants you can pull the old leaves off really easily but if you have to pull too hard, don’t do it. Use secateurs or you could damage the plant. Why or what the reason for these different types are, is unknown. They hybridise in New Zealand with the exotic, hardier, wide leafed but temperamental Mountain Cabbage Tree (Cordyline indivisa) and as much of the seed used to grow these comes from New Zealand, you can sometimes spot the difference. The Cordyline australis with slightly wider leaves will have some C. indivisa in their ancestry and will be more frost resistant than the true Cordyline australis which has quite narrow leaves. The difference in frost hardiness is probably only a couple of degrees and there’s not much you can do about it so why am I telling you all this stuff? Because it’s interesting!
For information and ideas on winter protection go to 64. Wrapping for Winter in the Glossary of Terms
Unfussy, when it comes to soil. Just avoid horribly waterlogged soils.
N.B. When clipping several plants with the same tool, have a bucket containing a 5% bleach solution and swish your blades around for 30 seconds between plants to sterilise them. This will help avoid the chance of cross contamination of disease.
As with all woody plants, plant high, exposing as much of the taper at the base of the trunk as possible. Allowing soil to accumulate round the base of a tree can be fatal. Keep very well watered when first planted.
Hardiness level Amber