When temperatures are high, some of our Bonsai need extra care. We provide as much shadow as possible and water carefully, but there is more you can do to protect your trees during heatwaves.
Before we discuss short term and long term measures to protect your trees, first let’s look at what happens to trees when temperatures exceed 90 °F (32 °C). At these high temperatures, some tree species slow down growth or even shed branches to prevent critical moisture loss. Optimizing the watering of your trees is therefore crucial. Tropical trees as well as Pines for example can take far higher temperatures than say a Maple, so make sure to check our tree species guides for specific information. Apart from high temperatures, low humidity is another risk during heatwaves as well as intense sunlight.
“High temperatures of the soil poses the greatest risk to your Bonsai.”
The roots of trees growing in nature are carefully protected from high temperatures, buried deep down in soil. Our Bonsai however are kept in shallow pots, and therefore the temperature of the soil (and rootsystem) can rise to dangerous levels. Dying and burned leaves, or branchtip dieback from intense sunlight can be a problem during heatwaves, but high temperatures of the soil poses the greatest risk to your Bonsai. Some signs of stress from a Bonsai during a heatwave include a pale color of the leaves, dieback of branchtips on conifers, and dying leaves.
Watering a Bonsai tree; this tree is potbound and would benefit from being repotted in the next early Spring! Let’s investigate what measures we can take to protect our Bonsai during high temperatures.
Short term measures
What follows is some advice for immediate care during a heatwave. Most importantly, water thoroughly and often, and make sure to provide as much shade as possible.
This Pine is placed in partial shade, at a spot that provides shadow during the hottest time of the day. It is part of the Vallejo Bonsai collection in Madrid, where temperatures often exceed 100 °F (38 °C) in Summer.
Long term measures
Here are some tips that need a bit of planning and building.
Crowding trees together helps to provide shade, especially to the smaller Shohin Bonsai. Also, trees in the garden provide shade in the afternoon.
Conclusion
With these short-term and long-term tips, your trees should be able to withstand heat waves well. Did we miss any tips? Please let us know on the forum!
