Most cordyline species are woody-stemmed, evergreen shrubs grown for their attractive foliage in shades of green, bronze, purple. They naturally and gradually loose the older leaves giving the plants palm-like appearance.
Cordyline australis is not fully hardy, but more mature specimens usually survive winter outdoors in milder regions or urban areas.
Plant in a sunny, sheltered position and fertile well-drained soil. Cultivars with coloured leaves are best sited in light semi-shade as the foliage can fade if exposed to strong sunshine. Plant out in spring to let the plant get established before the onset of winter.
Plants grown permanently outdoors do best in a John Innes No 3, with added grit.
Grow tender species such as Cordyline marginata, C. stricta and C. fruticosa (syn. C. terminalis) in containers using multi-purpose or loam-based compost such as John Innes No 2. Position in good light, but protect variants with coloured foliage from direct sunshine.
Water plants freely during the growing season, but sparingly in winter. Feed monthly with a balanced, liquid fertiliser from spring to late summer. Top-dress or pot up in spring. Seecontainer maintenance for more details.
Though frost hardy, young Cordyline australis plants, and also cultivars with coloured foliage are more prone to cold damage.
Prevent winter damage by tying up the foliage to reduce wind damage to the leaves and prevent water collecting around growing points and so causing rotting. In areas prone to severe winters, wrap the trunk with layers of fleece and place a 15cm (6in) layer of mulch, such as bark, over the root area.
Move container grown plants to a frost-free location, such as a greenhouse, during periods of cold or wet weather. Temporary shelter in a shed or garage in cold snaps will also help. Alternatively,wrap containers in bubble polythene, place them against a sheltered wall and protect foliage and stems with fleece.
Overwinter tender species indoors or in a heated greenhouse providing minimum temperatures of 5-15°C (41-59°F) Cordyline australis only needs the low end of the scale, around 5°C (41°F), but houseplants often need the warmer temperatures.
In favourable weather, plants flower freely. This causes no harm and flowers can either be removed or retained and cut out later when no longer attractive. Viable seeds may be collected in warm regions. For sowing, see Propagation below.
Pruning and training
Being dissimilar to conventional shrubs or palms, it can be confusing to know how to prune cordylines, if at all. Here's what to do;
Little regular pruning is required. Just remove dead leaves and spent flowers
The response to hard renovation pruning (best undertaken in mid-spring) is usually good. Cut back to sideshoots, basal shoots, or to ground level
After pruning, encourage new growth by an application of balanced fertiliser in spring
Create multi-stemmed plants by removing the growing point before growth begins in spring
Remove dieback or winter damage just above a new sideshoot, or cut back to a sound point on the trunk (below rot and damage)
Propagate cordyline from seed, cuttings or suckers, ideally from April to June. Pot up individually using well-drained cuttings compost. If possible, provide bottom heat.
Take terminal (shoot tip) cuttings 10-15cm (4-6in) long. Remove all the leaves apart from the terminal tuft
Prepare 5-7.5cm (1-2in) stem-section cuttings from thicker stems that include a bud. Insert the stem cutting horizontally in the compost with the growth bud just visible at the surface
Sever rooted suckers that arise from the base in spring and pot up individually. If the suckers have only a few roots treat as terminal cuttings (see first bullet point above)
Sow seeds at 16°C (61°F) in spring
Cordyline australis AGM: palm-like tree, branching sparsely with age. In the UK they reach 3-10m (10-30ft) in height, with 1-4m (3½-13ft) spread. Light green leaves. Panicles of white flowers produced occasionally in summer.
C. australis 'Albertii' AGM: matt-green leaves with red midribs, cream stripes and pink margins.
C. australis 'Torbay Dazzler' AGM: leaves with distinctive cream stripes, great for bedding displays. This is also a compact cultivar.
C. australis 'Sundance': leaves are flushed red along the midrib; great for bedding displays; and a compact cultivar.
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Cordyline plants can develop spots on their leaves, often in response to physical damage or stress such as exposure to cold wind, hail and winter wet.
Wet and cold weather in winter, and drought and heat stress in summer, can lead to poor growth, yellowing and browning of the foliage or excess leaf drop. Improve the growing conditions and provide winter protection.
Winter damage can also cause dieback of the crown. To avoid this, provide winter protection. Where it has happened, remove the affected growth. The plants ususally regenerate from the bare stems or produce suckers at the base.
Damage to the bark following a hard winter can also be associated with an infection known ascordyline slime flux.