How to protect your bonsai from heat

High temperatures and high sun exposure are the challenges that summer brings to bonsai lovers, their combination can cause a fast dehydration of the soil, burning of the leaves and general weakening of the tree. In this blog, we show you the best techniques to protect your bonsai from the heat and to anticipate to any problem.

Protect your bonsai from extreme heat

One of the most common mistakes in summer is to leave the bonsai exposed to the intense sunlight during the whole day. Although some Mediterranean species such as olive and pine tolerate the heat better, many others suffer seriously if they are not properly protected.

As we emphasise in our blogs, observation is essential when growing bonsai. In addition to following general recommendations, we must observe how our particular bonsai responds to different techniques and actions.

You may be interested in: The 8 most heat-resistant bonsai species

Ideal location and alternatives

The ideal premise is to find a location where the bonsai receives light in the morning and partial shade during the central hours of the day.

If you can get these conditions at home, perfect, but we know that this will not always be possible. You do not have a location that offers the desired conditions? Create it.

Shade nets

These meshes considerably reduce the impact of the sun on the bonsai, especially on the leaves, while allowing the light necessary for the bonsai to pass through, creating an ideal climate. If we find that this is not enough, we can add a second layer with a reflective mesh.

Wet environment

Other techniques to complement the previous one are those that allow us to create a more humid environment for our bonsai.

This can be obtained by placing a tray with water near the tree in order to increase the relative humidity and compensate for the dryness in the air.

The most common way is to place the bonsai on plastic trays, that contain some humid granulated soil (for example Akadama) on which the pot is laid. This keeps the bonsai pots moist and cool, so that they take longer to dry out.

Find our watering trays here.

Location

Place the pots away from walls and the floor. This will prevent the refraction of the sun’s light from giving more heat to the pots. We insist once again on observation. We will carry out a control of the leaves and the soil, in order to identify signs of hydric and/or thermal stress before it becomes a problem for the bonsai.

Adapt irrigation to heat

Watering in summer should be more frequent, but also more controlled.

The heat causes the substrate to lose water quickly, but as we already know, at any time of the year, and summer is no exception, excess humidity can be harmful to bonsai.

The heat makes the substrate lose water quickly, but as we already know, at any time of the year, and summer is no exception, excess humidity can be detrimental to bonsai.

A good watering routine, which is especially important in summer, is to water in the early morning or at dusk, providing different advantages:

• Minimum evaporation, so the bonsai can be better hydrated.
• Better hydration means better nutrition.
• When watering it is very possible that the leaves get wet, by watering at this time of day we prevent the intense sun, increased by the water, from burning the leaves.
• More efficient watering also means more sustainable watering.

Well-planned irrigation helps to reduce the negative effects of heat. Consult the irrigation section and equip yourself!

The soil is also essential to protect your bonsai from the heat

The soil type and its condition are important to protect your bonsai from heat. A suitable soil improves moisture retention and prevents root overheating. It is very important that the substrate of your bonsai is not compacted, this would prevent drainage and aeration, which together with the heat, would compromise the health of the bonsai.

The heat attracts guests to your bonsai

High temperatures not only affect the tree directly, but also create a favourable environment for the development of pests and fungi, with the extreme heat, as well as the combination of water and sun, your bonsai is more exposed to them. Also, the normal weakening caused by heat can make it more vulnerable to various adversities.

There is an easy solution! And for sure you already know it… Observe and check your bonsai regularly to anticipate and act in time in case of any suspicious signs.

Acer leaves in summer

In summer, it is inevitable that, as a natural defence of the bonsai against the heat, some of the Acer leaves will burn.

Although it is tempting, we do not recommend cutting them off, as this would force a new sprouting that would be a waste of the tree for autumn and winter. We will let the tree remove the leaves by itself, so that in autumn it closes the buds and will sprout again vigorously in spring.

We cannot prevent this from happening, but we can soften the impact with the techniques explained in the blog.

Do you want more information about Acer and its leaves in summer? Read the blog: My Acer’s leaves have scorched, what do I do?

What about indoor bonsai?

The blog has focused on advice for outdoor bonsai, as they are most affected by the changing weather conditions of each season. However, they also affect indoor bonsai in a lesser scale. Here are 3 tips for adapting your indoor bonsai to summer:

• They should be away from air conditioners or draughts from appliances such as fans.
• Increase the distance of the bonsai from the window in order to avoid a possible magnifying glass effect where the glass multiplies the power of the sun’s rays and burns the leaves. In any case, it is important that the bonsai receives enough sunlight.
• As with outdoor ones, they will benefit from creating a more humid environment with the help of watering trays.

These are the tips we offer you to protect your bonsai from the heat so that they look gorgeous and are affected as little as possible during the summer. We hope you have found this blog interesting and helpful, as well as those we recommend below:

Summer tasks on our bonsai

https://www.mistralbonsai.com/en/our-bonsai-in-summer-part-1/