The magic of mistletoe

Not only does it evoke the spirit of Christmas, says Monty Don, but there’s a touch of wizardry about mistletoe’s very existence

Twenty years ago I planted an orchard of 40 apple trees. Mistletoe often grows in the orchards of Herefordshire and I hoped my trees would host some. But nothing happened. It grew in great berried balls in the hedgerows around, preferring hawthorn, lime or poplar as its favoured hosts. But not a single sprig on any of my apples. Then about three years ago I noticed a little green shoot appear and since then there have been about a dozen new growths of mistletoe, some of which are growing very fast. It has been quite a wait but now my orchard is feeling blessed by a touch of mistletoe magic.

Why did it take so long? To understand that you need to know how mistletoe grows and how it is spread. Birds – especially the mistle thrush and the blackcap – love the berries, but once they’re properly ripe around February, which is when the birds will be attracted to them, the flesh that surrounds the seeds is very sticky. So to clean their beaks, they wipe them on the branches near where they’ve eaten and in the process deposit seeds that adhere to the bark with the glue-like flesh of the berries. They also excrete the seeds onto nearby branches, but from either end a seed is deposited amongst a blob of binding material.

For many years no one really understood why mistletoe flourishes in the western side of the UK but not nearly so well in the east. However this situation is changing and it has been observed that there is a direct correlation with the increased migration of blackcaps from Siberia, together with milder, wetter winters which seems to be an important combination.

It is a fallacy to think that the seed needs to be put under a flap of bark in order to germinate. In fact, it needs light to trigger germination. As it puts out a tiny shoot a root bores into the bark and the stem of the tree. But the bark and the wood beneath it have to have a certain consistency which only comes with age. Hence the lack of mistletoe in my orchard until the trees had become large enough to be a suitable breeding ground. It takes another two years for this tiny seedling to establish itself in the tree but after that it will grow fast, spreading its roots down into the centre of the branch and eventually completely filling it, like the spokes of a wheel.

Mistletoe does, of course, have green leaves so can photosynthesise but it also takes a lot of nourishment from its host tree, so is semi-parasitic. Ultimately, this is its downfall. The roots of the mistletoe become so congested that they block off the moisture and nutrient supply to the host branch so that it dies off and the mistletoe dies with it.

If allowed to spread and take over its host tree then it will probably hasten an early demise. So the answer is to prune it every year, taking what you need for Christmas decoration. Nothing could be easier as the mistletoe wood is very brittle and simply snaps off with a tug.

While this plant that grew in mid-air without any soil and kept its green leaves all the year round as well as producing strange white, milky berries was bound to be associated with midwinter magic, it only became directly connected to Christmas in the 17th century, and the tradition of kissing under a bunch or sprig of mistletoe was established about 150 years ago in the Victorian era. The tradition used to be that every time a kiss was taken a berry would be removed and then when all the berries were gone the kissing had to stop.

Monty admires his mistletoe