It sounds as though it should be an ancient pagan custom, but it isn't. Tree Dressing Day was only introduced in 1990, by arts and environmental group Common Ground, and always takes place on the first weekend in December.
On its website, Common Ground says:
"Trees have never lost their importance to us, but we have often forgotten the breadth of their value and meaning. They carry stories and put us in our place, outliving us if we let them, by many generations. In towns especially, they help to clean the air, fix carbon, reduce noise and flash flooding, provide oxygen, shade, beauty and attract wild life, yet are under constant threat from vandals, vehicles, and over-cautious councils and insurance companies. Often we take them for granted, and feel sad if we have acted too late to save them."
Although Tree Dressing Day started less than two decades ago, it draws on many traditions from across the world that celebrate trees, some of which are quite old. In many parts of the UK there are folk customs involving tying ribbons to the branches of trees near wells in the springtime. This is called Well Dressing.
In Aston-on-Clun in Shropshire, on 29 May, people honour the Arbor Tree - a black poplar standing beside a stream where four roads meet - by attaching flags to it. This custom is known to date back to at least the Victorian era, but may be based on an even older tradition.
The first weekend in December is when many of us will be decorating our Christmas trees - or Yule trees as pagans prefer to call them. This is another tradition that seems ancient and has often been said to have pagan origins, but can only definitelybe traced to 16th century Germany. It didn't became popular in England until Victorian times, although people had been bringing greenery into the house for midwinter celebrations long before that.
But, although Tree Dressing Day might be a modern festival, gathering outdoors on a cold and frosty winter's day to honour living trees seems to me far more pagan than hanging plastic tinsel and mass-produced decorations to a fake or dead tree that has been bought in a shop and then driven in a car to a modern central-heated home.
I know I will be looking out for Tree Dressing Day celebrations near me.
Events this year take place in nature reserves and country parks, village greens and woods, arts centres, libraries and museums all over the country. You can find out about some of them on the links below. Alternatively, have a look at your local council's website for events in your borough.