And so here we are deep into winter and a new year full of hope and expectations. Now is the time to protect your less hardy trees, (almost all tropical trees fall into this group), reflect on the year now gone, what grew well and what did not? and to prepare for the coming spring.
Some trees need a little bit of extra care over the winter months. Tree types which should be inside during winter:
- Chinese Elm
- Chinese Privet
- Dwarf Umbrella Tree
- Dwarf Jade
- Fukien Tea
A bright south-facing windowsill away from direct heat (e.g. on top of a heater of any kind) will keep them happy and healthy as long as you remember to keep the soil moist.
Top tips for the cold dark days of winter:
Avoid wind. The wind is the most dangerous element in winter as cold air can dry out trees quickly. Trees that dry out in winter are more likely to lose branches or die.
- Keep trees well-watered. Dormant trees don’t completely shut down in winter. As such, they will continue to need water. Bonsai trees in warmer and brighter places may require watering more often than those in colder spaces. Watering once a month might be more appropriate for trees in cold conditions.
- Reduce temperature fluctuations. For most temperate types of Bonsai trees, the goal is to maintain temperatures between 1-5° Celcius throughout winter. Cold enough to meet dormancy requirements without exposing trees to harmful temperatures.
- Reduce freeze-thaw cycles. Trees that freeze and thaw frequently experience more stress than trees that consistently stay just above or just below freezing.
- Maintain dormancy for as long as possible. As we’ll cover below, spring care can be challenging in cold climates as late freezes can damage new growth. By keeping trees dormant until freezes become infrequent, you can help your trees grow successfully in spring.
With these criteria in mind, here are some notes about popular approaches to winter storage for bonsai.
- Place trees under benches. If your winters are relatively mild but temperatures can drop to the -6° C, placing trees on the ground or under benches can provide additional warmth and shelter trees from heavy snow loads.
- Bury trees in the garden. Dig holes big enough for bonsai pots and backfilling them with dirt just over the lip of their container. You can provide insulation for the roots while exposing the tops of trees to the elements. Shovelling snow around the trees up to the first branches can provide additional insulation.
- Place trees in covered or uncovered mulch beds. As an alternative to burying them in the soil in the garden.
Perhaps the most important thing to remember as always is to remember to talk to your trees on a daily bases. Do not forget them even if they have entered into a deep ‘winter sleep’! They can still tell you how they are doing. You only have to listen!