GROW:True mistletoe lovers who are determined to have it in their own gardens will be happy to know it's not that difficult to grow, as long as you follow a few cardinal rules: watch out for slugs and snails; stick the seed on the branch of a suitable tree. After that, it's a matter of patience, writes FIONNUALA FALLON

VIRGIL MENTIONED it in the Aeneid, Pliny the Elder wrote of its significance for the ancient Celts as a herb used in their druidic rituals, while the writings of the German botanist Carl von Tubeuf and the 20th-century Austrian philosopher and mystic, Rudolf Steiner, began modern research into its potent powers as a treatment for cancer. But while the ancient druids harvested it barefooted, clad in billowing white robes and bearing sharp, golden sickles, the staff of the National Botanic Gardens in Glasnevin have found that a cherry picker, a long-armed loppers and a warm winter coat are slightly more convenient when it comes to picking bunches of the beautifully decorative, white-berried, parasitic evergreen we know as mistletoe.

In the past few weeks, several trailer-loads of Viscum album (or ‘drualas’, to give it its Irish name) have been laboriously harvested from some of the gardens’ tallest trees, including a large lime tree growing just next to the Palm House which was so heavily festooned with the ‘parasitic phanerogam’ (mistletoe’s more technical description) it was in danger of becoming unstable.

“It might look lovely at this time of year but heavy infestations of mistletoe can do an awful lot of damage to a tree, even kill it,” the gardens’ director, Matthew Jebb, explained to me on a recent visit.

“Look closely at the point where the plant is growing into the tree and you’ll see obvious distortions or swelling of the branches. And because it’s an evergreen parasitic plant that is transpiring throughout the winter while depending totally on its host plant for water, it causes particular stress to deciduous trees that don’t, so to speak, have a full set of sails at this time of year. There’s also the risk of water freezing in the tree’s xylem after a harsh frost. Even in spring or in periods of drought, the competition for water can become such a problem that you’ll start to notice leaves dropping.”

Careful plant husbandry aside, there is another, more altruistic reason for the recent harvesting of the National Botanic Gardens’ mistletoe. Over the past few weeks, hundreds of seasonal bunches of the plant have been auctioned off to visiting members of the public in aid of St Michael’s House National School in Ballymun, one of six national schools run by the Dublin-based organisation that provides services for children and adults with intellectual disabilities. All proceeds will help to fund the construction and planting of a school garden, designed by the Botanic Gardens curator, Paul Maher, in careful consultation with the pupils.

“As a fundraising idea it first occurred to me quite some time ago”, says Jebb, “but it took a while because mistletoe is quite a slow-growing plant and we only need to strip it off the trees every couple of years.”

But why, one might wonder, does the plant grow with such abundance in the gardens when it is quite a rarity elsewhere in the country? Almost certainly the answer lies with Dr David Moore (1838-1879), a previous curator of the National Botanic Gardens and the man whom Jebb thinks probably first deliberately introduced the plant to the gardens. Since then it has advanced slowly but surely, and now grows on many of the gardens’ different specimen trees, including apple trees (the plant is traditionally associated with orchards), maples, robinias, davidias, limes, crataegus, sorbus, poplars and even betulas – but not, despite the ancient Celtic druids’ preference, on any oaks . It has also, Jebb adds, more recently been spotted close to, but outside, the gardens’ perimeters, growing on trees in nearby private gardens. “In the last few years it’s definitely growing a great deal more than it used to – we’re not quite sure why.”

As to how you might deliberately introduce the parasitic plant into your own garden, Matthew Jebb’s advice is it would be better not to. But those true mistletoe lovers (and there are many at this time of year) who are still determined to try will be happy to know it’s actually not that difficult to grow, as long as you follow a few cardinal rules.

“The first mistake that people make is trying to sow the seeds at this time of year, when they’re not fully ripe,” explains Jebb, adding the plump, pale, sticky and highly poisonous berries only truly ripen roundabout March.

His next piece of advice is to watch out for slugs and snails, which will hungrily devour the seeds and seedlings of mistletoe even when they’re high up on the branches of a tree. “So stick the seed on to the branch of a suitable tree – probably the best choice would be a poplar or an apple tree – and then protect the seed by strapping it on to the tree using nylon stockings, which will prevent the slugs and snails from eating it.”

After that, it’s a question of patience, as mistletoe only flowers and then berries after an average of five to seven years.

In the meantime, apparently there is a certain established protocol to be observed as regards the ancient ritual of kissing under the mistletoe. According to Kevin Danaher and his classic book, A Year In Ireland, “a girl would hang a sprig over the door and then kiss the first unsuspecting man who came in; by custom he then had to buy her a Christmas present”. The other important rule is for each kiss stolen under the mistletoe, a berry must be plucked from its branches. No more berries means, sadly, no more kisses (or presents).

Better make it a good one . . .