Some bonsai are deciduous and will lose their leaves during winter. The acers dropped their leaves several weeks ago, and our Chinese Elm bonsai will shortly start to drop theirs. First the leaves turn yellow, then they fall. Contrary to what some people think (every year we get a few customers who contact us to say their trees are dead), the trees have not died, they are resting and waiting for Spring when new leaves will appear.
Chinese Elms in particular need a rest, a period of ‘dormancy’. If you have a bonsai of this species it is important that your tree spends a month to six weeks in a cooler environment if you keep the tree indoors during the rest of the year. If possible place your tree outside, in a garage, or shed – light is not too important, although the tree should still be watered every 10 days or so. If you are not able to place your tree outdoors, move it to the coolest place in the house – some people even keep their tree in a fridge!
After a rest your tree will be ready for new leaves and a new year. However, try to trick your tree into thinking it is permanently summer by keeping it in a warm room above a radiator will harm the tree.
Evergreen trees don’t need dormancy and will happily live in a warm spot, but cut down on the watering in winter.