So, during the much higher than usual temperatures here in the UK, I have learned another valuable, but fortunately not fatal, lesson.

I noticed my Elm started shedding leaves as if it had suddenly decided autumn was upon us. I was concerned after a couple of days of finding dried up and yellowing leaves on the floor. An otherwise healthy tree appeared to be struggling. I had been watering more often, and checking my trees a bit more than I normally do, but hadn’t fully appreciated the effect this heatwave would have. The ficus hasn’t shown any distress, but deciduous trees are, apparently, a different matter.

A quick bit of research led me to other stories and advice. Luckily, I’ve been home this week so was able to keep it misted, and kept it in the shade on the patio coping stones, and also kept the ground around it wet so as to further help with humidity.
One source cited that above 30 degrees C, some species will show signs of distress, and that thermal death can occur above 45. Also, the transpiration rate can be a lot higher than the ability of the tree to uptake moisture through the root system. On top of that, fertilising may need to be altered, or withheld in some cases, due to increasing nitrogen levels and further stressing the tree.

I’m sure many of you know this already, so this post is really for those of us, me included, who haven’t fully considered what high levels of prolonged heat can have on your trees.

If there’s other advice or knowledge that can be added to this post, feel free, and maybe we can save a few more trees!!

Today is the first day for a long time that I have not had to water at least twice every day. I never mist just plenty of water. Most of my trees are in full sun as I have little shade in the garden. I have not had problems with most species, the only one is one of my White Beech which had a few burnt leaves but has since recovered.

I'm getting used to this tropical sun+bonsai here in Brazil.
Some species, like maples, suffer leaf burn, and even tropicals like calandras have to be protected from the strong midday sun.
And... Plenty of water!
Now I imagine this unusual summer in Europe, with temps getting over 40C, how the temperate trees behave... Quite badly I suppose.
Leaf burn is the smallest of the problems, I guess.

Here in Alabama exactly what you describe happens almost every year with some trees, not just bonsai but the trees in the yard and the trees on UAB campus. I have wondered if it happens to ornamentals not from this area but that is just a guess.

They almost all come back ok and grow more leaves. They have another two months at least before time to fall off the tree, so they can make their contribution to the tree.

No real problema. But i have been watering twice a day. Only during my holidays me tree sitter missed a few trees and did not check again for 4 days. I asked him to come every third but well.. lost 3 trees that the sprinkler did not cover well enough. The rest is doing well, mostly. Beech are in their 4th growth phase this year..

@Cliicio

It’s interesting you mention that actually, as I recently read that many tropicals will suffer in full, direct and strong sun. In their habitat, they are generally shaded slightly by other trees and receive, effectively, filtered sunlight.

I suppose we can add to that the fact we are keeping them in small pots as well.

Franky wrote: @Clicio, many tropicals will suffer in full, direct and strong sun. In their habitat, they are generally shaded slightly by other trees and receive, effectively, filtered sunlight.
I suppose we can add to that the fact we are keeping them in small pots as well.

Exactly.
And many trees receive direct sun only in the canopy (when living in a tropical jungle), and the soil and smaller trees never get hot.

While my trees are fine this is a pic I took two days ago of a street near where I live. It looks like Fall.

that's tropica heat! The plants go dormant here during high-summer (February)

I’ve got fatality with a Nothofagus antarctica, which didn’t supported the sudden weather change from 23C rainy to 36 sunny.
JM Deshojo got some new leaves scorched, but nothing serious.
Others looks fine, except that all my outdoor moss dried which ones was full contact with the sun on the past two weeks.