GARDENS:Cold winter temperatures have been hard on cordylines, but if yours is looking a bit sad, don't despair, here's how to revive it

AT PRESENT, THEREis a particular plant causing a lot of worry in Ireland. Its name is turning up regularly in my email box, and it is also popping up frequently in the search terms on my blog (onebeanrow.wordpress.com). I'm talking about Cordyline australis, also known as the cabbage tree, and – in local parlance – "palm tree". As any gardener will tell you, it's not actually a palm, or even remotely related. But this New Zealand native (which was introduced to Europe in 1823) lends a tropical appearance to gardens and public spaces throughout this island.

Or rather, it did – until the last two severe winters wrought terrible injuries on thousands of specimens. Snow flattened the trusses of leaves, but worse still, frost got into the stems and trunks, and turned the cells to mush. The damage from the prolonged freezing temperatures was not immediately apparent. But a few weeks after the thaw it became clear that all was not well. Leaves started to drop off, upper stems became flaccid, and in some cases – as the tissues inside began to rot – trunks began to ooze and produce fuzzy growths of mould. After the wars of winter, this country’s army of cordylines has come limping pitifully into spring.

But not all specimens have suffered so dramatically: in my town of Dún Laoghaire the cabbage trees are intact, and display hardly any evidence of trauma. The same can be said for cordylines along the coast from Dublin city to Dalkey. And there are many other mild areas where they have suffered only slightly. Cordylines are hardy in a normal Irish winter, and can cope with occasional temperatures of minus five to minus 10 degrees Centigrade without too much fuss. It’s when the deep freeze lasts for days on end that the plants start to get into trouble. In much of Ireland, last December’s weather was both bone-chilling and cordyline-killing.

This isn’t the first time that we’ve had cordyline bother. Kathryn Marsh, organic gardener and teacher at Sonairte in Co Meath, remembers the desperately cold winter of 1982. “We were living in Rush then, which was ‘cordyline central’.” After that cold spell, she says, the older and thicker-trunked individuals pulled through, while the slim ones bit the dust. The top few feet of the survivors were cut back by the frost, but new branches appeared lower down the trunks, and the trees lived on. At present, Marsh lives north of Balbriggan, “in a frost pocket”, where the temperature plunged to about minus 15. Of two cordylines that she grew from seed 15 years ago, one has been killed, and the other, although “battered, is going to be fine.” The fortunate one, she says, has a thicker stem, but – just as importantly – there is more air movement around it, so the frost did not settle so deeply into it. A sheltered position can sometimes cause cold air to pool and gather, so a seemingly benign microclimate can sometimes turn treacherous.

To cut to the heart of the matter, as it were: if your cordyline looks dead, is it? And how do you find out?

Well, if it is just looking a bit shook, and has lost its leaves, chances are that it will make a full recovery. New shoots will sprout directly from the trunk, and away it will go, with a bushier profile than before. If there are too many heads for your taste, carefully cut out some of the new shoots so that there are fewer growing points. By midsummer, if the stems above the new shoots are dead and unproductive, carefully prune them out with a saw to tidy up the tree.

But what if the trunk of your cordyline has turned to mush and the whole thing is sagging? Is there hope? Yes, there is. Wait until about May, and then perform some surgery (you don’t want to shock the tree further by operating while the weather is still cold). Feel all the way down the trunk, and if it becomes firmer nearer the base, then cut away all the rotting tissue above that. And then, wait. In time, you may get new shoots. Sometimes cordylines regenerate from the base, at ground level, which can take up to a year.

I have a special place in my heart for cordylines, especially in seaside locations or in jungly plantings in gardens. The flowers, which bloom in May, and go on for weeks, are highly scented and much beloved of bees. The abundant, waxy fruits are high in fats and provide nutritious meals for many birds in late autumn and winter. I don’t recommend planting it in the colder parts of Ireland, but if you live in a favoured area, it’s worth giving it a whirl.

Love Monty? Love Italy?

Then you have a double treat in store. Next Wednesday (BBC2, 9pm) sees the start of a new television series, Monty Don's Italian Gardens, while the book, Great Gardens of Italy, by Monty Don, with photos by Derry Moore (Quadrille, £25/€28.50), was published last month. Delizioso!