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Martyn Davey, Head of Horticulture and Design, Easton College
Tuesday, February 21, 2012
I cut down the main trunk of my cordyline because the top half had been severely damaged by the prolonged cold spell last winter. There are lots of shoots coming from the base but should I prune out some of them, allowing the rest to get stronger, or leave well alone? (B Butler, via e-mail)
Cordyline australis has become one of those plants many people have in the garden. It has established well as our climate had been getting milder – until last winter when most cordylines fell victim to the big freeze.
Most cordyline species are woody-stemmed, evergreen shrubs that provide attractive foliage in shades of green, bronze and purple. They naturally and gradually lose the older leaves giving the plants a palm-like appearance.
Cordyline australis, although widely grown outdoors, is not fully hardy, however more mature specimens have survived winters outdoors in milder regions or urban areas.
Plant them in a sunny, sheltered position and fertile, well-drained soil. Cultivars with coloured leaves are best in light semishade as the foliage can fade if exposed to strong sunshine. Plant out in spring so they get established before winter.
Cordylines are unlike conventional shrubs or palms so it can be confusing to know how to prune them, if at all. Pruning generally should be limited to removing dead leaves and spent flowers.
Where plants have been hit by hard frost they should be cut back hard, as you have done, in spring. This stimulates lots of new growth from the base as the roots are rarely killed by even a severe winter.
After pruning, encourage new growth with an application of balanced fertiliser in spring. This growth can be left to form a multi-stemmed plant.
To produce a single-stemmed palm pick the strongest new shoot and grow that up. The other shoots coming from the base can be removed and used as cuttings. Sever rooted shoots that arise from the base in spring and pot up individually.
If the suckers have only a few roots, treat them as terminal cuttings, giving them some basal heat until they are well rooted. Cordylines are very easy to propagate in this way.
Your plant should now be treated as a new young plant and it will need to be protected from further winter damage by tying up the foliage to reduce wind damage to the leaves and prevent water collecting round growing points and so causing rotting.
In severe winters, wrap the trunk with layers of fleece and place a 15cm layer of mulch, such as bark, over the root area.
•This article was first published on September 24, 2011.