The short answer is No, you can’t leave your lemon tree outside in winter. Lemon trees are not hardy in the British climate, even in the warmer South. Lemon trees need some warmth and humidity, neither of which is found outside in the cold winter months.

So, what should you do with your lemon tree in the winter? You need to move it indoors when the nights start to cool off. We’re assuming here that your tree is planted in a pot that can be moved inside. But to where?

Bring the lemon tree inside in winter

Lemon trees still need light in their dormant stage in the winter. Ensure that their winter home receives four to six hours of sunlight a day by positioning them near a window. Don’t put the lemon tree in a centrally heated room as the air there is too hot and dry for the tree’s comfort. Your best choice is a cool, frost-proof space such as a garden shed or an unheated greenhouse.

You may have no choice but to bring the lemon tree into your heated house. If so, you need to set up a moist environment for it. Increase its surrounding humidity by standing the pot on a large saucer or tray filled with gravel that you keep moist. Make sure the water is below the level of the gravel though. This is so it’s not drawn up into the tree’s roots and waterlogs them.

In addition, make sure to mist the plant regularly through the winter to keep the humidity high.

If you must leave your lemon tree outside in the winter, make sure to wrap it in fleece (preferably the horticultural kind). Also wrap the pot with burlap or lagging and place it all in a spot sheltered from the wind, perhaps in a protected corner of your patio.

I have more information about how to look after a lemon tree in general and why your lemon tree leaves might be turning yellow here