Keep it simple Sunday: Are cordylines hardy?
Are cordylines hardy?
Another question that originated with my niece (see last week for an explanation). Apparently she went to her local garden centre to buy a cordyline and was told that it was ‘not for you’ and was directed to buy a pack of violas!
Having worked in garden centres, and spent many hours advising customers on the best plant for their garden, only to watch them buy exactly what they intended on buying before they spoke to me, I have some sympathy for all concerned. But I can’t see how a viola is a substitute, in any way, for a cordyline.
Cordyline australis looks exotic and is exotic, hailing from New Zealand where it is found on both islands, showing great diversity of form and of hardiness. It is not from Australia and ‘australis’ simply means ‘southern’.
When I started writing about gardening it was an annual job to swathe cordylines in a protective blanket in winter. The leaves would be tied up and wrapped in hessian to prevent water and cold getting into the growing point. Unfortunately this behaviour ‘blanches’ the centre of the plant and when the wrapping is removed, the central portion is white and falls apart. It is for this reason that I always say to install this protection for as short a period as possible, if at all. The practice fell from favour as we had a run of milder winters, but then the cold winters of 2009-2011 stopped us, and our cordylines, in their tracks.
The whole question of hardiness is a complex one. Some plants are completely hardy. These include shrubs that drop leaves and protect their growing points in scaly buds. Most native plants (Northwest Europe) are hardy. Some plants that are hardy in winter come from areas of the world where spring is more consistent than here. As soon as it starts to warm up in spring they come into growth but they can be ‘caught’ by late frosts, after growth has started, in our strange climate. These plants are difficult to accommodate in this garden. Corylopsis has been killed and calycanthus is now smaller than it was 4 years ago. Japanese maples get caught too. Stop/start springs are a constant worry.
Plants from areas of the world where there are not cold winters often have no resting buds. These plants include acacias, fuchsias and escallonias but there are many more. Cordylines are also not adapted to cold (frozen) spells. The growing point is at the base of the long leaves where water can collect and freeze. Then the growing point dies and, come spring, all the leaves drop off.
Which is all a preamble to the question of ‘are cordylines hardy?’
There is no easy answer because different types vary in how much cold they can withstand. There is a lot of genetic diversity in the wild and selection might increase hardiness. But, as a rule, cordylines with narrow, green leaves are the hardiest. Those with broader leaves are less hardy. A lot of the large plants sold in garden centres are grown in southern Europe and imported and these have not had to cope with northern winters. Variegated cordylines are less hardy, though my ‘Torbay Dazzler’ survived the winter of 2010 (more below). Red-leaved cordylines are also less hardy than the green and are less robust.
Cordylines are common in coastal landscapes. They withstand salt-laden winds and coastal areas are less prone to hard frost.
Interior, elevated landscapes, that tend to be cold in winter, are less suitable.
Remember that if grown in a pot on the patio the roots are more exposed to frost than if grown in the border. And always use a loam-based compost. But, in a pot, it can be moved undercover (with light) to protect it from cold and wet.
The actual conditions in a garden can ameliorate the geographical climate. A south-facing position is milder than one facing north. An urban garden will be warmer in winter than a rural one.. A well-drained, sandy soil will make success more likely than a wet, clay soil.
So, to get on with it, are cordylines hardy?
It depends on the type and it depends on the winter. Cordylines were an obvious component of Irish gardens before the cold winters of 2009-2010-2011. This killed a lot, along with escallonias. But cordylines will sprout from the base if the growing point is killed. It may take a few years to get the effect you want but they may well sprout from the base if the top is killed.
When it comes to hardy palms, and I grow all four generally-accepted ‘hardy palms’, trachycarpus is the best suited to winter cold, but it is slow to grow and expensive. Cordylines are relatively inexpensive and the green forms are the cheapest because they are easily grown from seed.
Unless you are in a very cold area I think they are worth the risk but I suggest buying smaller, green plants to experiment with. They grow quite quickly and you won’t lose too much money if the plant does not survive. It is best to plant in April or May so the plant has all season to get established before winter.
Just a few more relevant facts: The long, fibrous leaves drop all year round and many gardeners hate this, especially when the leaves fall onto lawns. When mature, large heads of small, fragrant flowers are produced and these are pretty amazing. In warm summers there may even be clusters of blue berries.
The Biking Gardener 
Chill can be more damaging in conjunction with moisture, or so it seems to me. I am surprised to see how popular the more resilient types of Cordyline are in the Pacific Northwest, but those on the foggy coast seem to be less happy than those farther inland. (This included the old fashioned ‘ashy’ bronzed sort, as well as the common green sort.) The weather in Ilwaco on the coast does not get as cool as that of the high desert of Eastern Washington, but Cordyline seem to prefer the cooler inland weather just because it is also more arid while cool.
That is interesting that they don’t like the coastal fog – I would have thought that would suit them. But yes, damp AND cold is the issue.
Exactly, since it is native to islands of the South Pacific, and some of the places that it naturally inhabits get as cool as the weather can get here.
A little off topic, except as it relates to the interaction between the person at the garden centre and your niece, you have reminded me of an incident from many years ago. We had a local gardener, a self-appointed expert, a garden snob, a grower of the rare and unusual, who approached a local nurseryman for a very special plant, which he knew was in stock, only to be refused mainly because the nurseryman didn’t like him nor his approach and attitude to gardening. When he pressed for a reason he received the response, “I don’t think your garden is ready for such a special plant yet!” He left emptyhanded and deflated.
Oh dear – that was harsh! But, being a nursery and the person had carefully raised the plant I can understand why they didn’t want the plant to die.
Oh, he just didn’t want a pretentious prat to have it so that he could simply boast about it!