Until the 19c decorations were left up until Candlemas on 2 February, 40 days after the birth of Christ.
Some people believe that decorations are taken down because of a pagan belief that spirits lived in the tree and holly and would cause mischief if not returned to the wild.
Well the Victorians were having none of that and decided 12th night ie 5th January was when the decorations should come down and they burned them to boot – tough on the tree spirits.
There’s an argument to be made for waiting until Three Kings’ Day on 6 January. This is celebrated in catholic countries where you see children dressed up as the Kings bearing gifts.
And if you are an Orthodox christian your Xmas Day is 7 January anyway so you could keep them for days after that.
I’m leaving mine up for a while yet together with the Xmas themed template for these posts. The snow on it will stop falling soon and I’ll go back to my usual theme after that.