During the summer, when the air temperature is very high, if no special measures are taken to protect the bonsai, the plant may be damaged or dry out. The plant cools down through the evaporation of water from the leaves. At high temperatures, the plant quickly loses moisture. When insufficient water is supplied to the bonsai in the heat, the leaf temperature may reach a critical level. Wilting of the leaves is the first symptom of water shortage. In intense heat, the plant may prematurely enter a dormant state (like in autumn). The leaves change color and fall, first the inner and lower leaves of the branches, then the rest. When the bonsai is exposed to direct sunlight, the soil in the container also gets quite hot. High temperatures can also damage the roots. In such conditions, the plant becomes more susceptible to diseases and pests.
The plant can withstand very high temperatures quite well if normal conditions for its functioning are provided. There are several simple methods to protect the bonsai from very high temperatures:
- Protect it from the midday sun's direct rays, or provide some shading.
- Do not place the bonsai on a surface that heats up significantly from the sun, such as stone, concrete, or metal.
- Try to increase the humidity around the bonsai: spray water more frequently and water the area around it.
- Make sure that the soil in the container does not dry out completely.
- Watering in the afternoon is another method to cool the roots.
- If you have many trees, place them close to each other, so to speak, cluster them together. This way, the branches will shade the containers, and the moisture will be better maintained.
In the summer, small bonsais require special attention. During this time of the year, they may need to be watered up to three times a day.
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