Cabbage palm - far more resilient than given credit for

Like the mythical phoenix, the bird that rose from the ashes, a great number of cordyline trees have risen up after apparent death by freezing.

The twin cold winters of 2009/2010 and 2010/2011 were so harsh that it looked like this very common and very popular garden tree might have reached the end of the line. But no, cordyline has proved itself to be more resilient than given credit for.

Part of the reason for the popularity of cordyline is that it is exotic, both literally and in appearance. It is native to New Zealand, which makes it an exotic species, and it looks like a palm tree, which is exotic of appearance in Irish gardens.

It got the rather unexciting name of ‘cabbage palm’ from early New Zealand settlers’ use of it as a vegetable, most likely emulating the native Maori people, using the soft growing bud at the heart of each rosette of leaves as a vegetable.

Despite the name cabbage palm, it has connections with neither the cabbage nor palm families. In fact, it is part of the agave family, which is connected to the greater lily family.

In flower, it produces a huge head of tiny white flowers, often 1m long and nearly as wide, like a great chandelier hanging from the centre of a rosette of broad strappy leaves.

It is evergreen, of course, but sheds the dead, dried-out leaves for much of the year and, as anybody who has tried to mow them off a lawn knows, these are tough and stringy. These leaves get caught around the blades and can cause a lawn mower engine to cut out.

In a sunny summer, the flowers go on to make small berries that dry out and carry the black seeds, which are very like onion seeds, another member of the greater lily family.

The seeds are viable and may germinate in gardens, typically in a rock garden or flower border, where they are not really wanted.

It is not uncommon to see an occasional self-sown seedling cordyline growing by the roadside or on waste ground.

This ease of growth from seeds is a reason why the cordyline found its way into so many gardens. It became a cottage garden plant of sorts. It is easily lifted when still small, but nearly impossible to shift its deep taproot when over 2m or more.

The tree is not a true tree, botanically, but a large perennial flower with a tough stem. It starts off as a single rosette of leaves and generally only branches after it flowers, splitting into two or more rosettes.

Old plants can be 5m or 6m tall with a much-branched head – but that takes a century or so. It does not really appear away from coasts much because young plants are easily killed outright by normal winter frosts.

Nonetheless, in those winters, large numbers of these old trees and smaller ones were severely damaged by hard frost to minus 18°C. Many had the leaves progressively turn brown and shed, leaving only stumps. The branches and trunks of many rotted into a stinking mess and collapsed.

Despite being killed to ground level, a high percentage, perhaps 90%, survived and produced new shoots in the following summer or even in the second year, in some cases the shoots coming up from below ground level where there were side-buds, normally dormant.

In the years since, many cordylines have recovered perhaps half of their height, powered by the undamaged deep taproot.

The plain green sorts fared best, as the coloured selections are not as hardy. These include a purple-leaved form, the striped ‘Albertii’ and cream-striped ‘Torbay Dazzler’, shown.

So the initial fears of the loss of a tree characteristic of Irish coastal gardens proved unfounded, and the cordyline will continue to be a signature plant in Irish gardens.

Harness the beauty of winter heathers

Winter heathers are popular but should be even more widely grown. There are few enough plants that flower as the heather does, depending on variety, from November to April. Big enough to be used at the front of borders, or in winter pots, it can be used on banks or in rock gardens too, so it is very versatile.

Its flower colours are shades of pink-purple and white, long-lasting and resisting harsh weather. They look really well with spring bulbs nearby, snowdrops, crocuses and daffodils, especially the miniature sorts.

Its widespread use for ground-cover is not a great idea, because, while it is in flower in winter, it looks very dull over a large area in summer. Use it in singles or trios to avoid summer dullness, but gain its value in this season.

>> This week

Trees, shrubs and roses

Plant bareroot hedging, shelter and woodland trees. Rose bushes can be planted at any time. Bush roses are already showing good growth and they, and repeat-flowering climbers, should be pruned right away, if not already done. Control weeds around the base of young trees and shrubs.

Flowers

Lifting and dividing of herbaceous flowers can resume if the soil has drained. This is the best time to move perennial flowers in gardens on heavy soil. Take the old leaves off hellebores if there is much black spotting. Seeds of geraniums, busy lizzie and bedding begonias can be sown in a propagator.

Fruit, vegetables and herbs

Finish off pruning of apple and pear trees and currant and gooseberry bushes. Fruit trees and bushes should be planted within the next few weeks. Sow seeds of early varieties of cabbage, cauliflower, carrots, lettuce and onions in a tunnel or glasshouse to plant out for an early crop in April.

Lawn

Grass growth has taken place right through the winter. When the ground is firm enough, mow the grass at the first opportunity and repeat it after a few weeks. This will leave the lawn area looking neat and tidy before growth really starts. Apply sulphate of iron if there is heavy moss growth.

Greenhouse and house plants

Greenhouse peach trees should have the first flowers gently pollinated with a small soft paintbrush or by vigorously tapping on the support wires on a dry sunny day. Begonia and gloxinia tubers can be started in a greenhouse, or on a windowsill indoors. Begin watering the greenhouse as it warms up.