I had the majority of my plants do this last year. I was assuming that it was the amount or intensity of the light. They did not do this, this year. Our summer was unbelievably hot and I had to put 60% shade cloth over the roof of my outdoor roofed area. Sorry not to be able to give a definitive answer.

With the Brugmansia that I grow, this is something that they do as the sun sets. Then the leaves open up in the a.m. as the sun comes up.

Rick

Thanks for the reply Rick.. How hot is hot wherever you are in Canada?. I live on the Hawaiian island of Maui (Canadian & USA citizen) where our temperatures are still hovering around 90 degrees F. and won't moderate for another month.. Let's see if anyone else can solve the leaf mystery so it can be avoided in the future.

Like Rick we had unusual temps and humidity for us (summer heat). Now we are cold. I have three, 5 yr old obesum that I pruned for more branching grow leaves up. I thought it was to much light. The branches are very close together. I might try wiring the branches for a more umbrella shape. The others I had pruned at the same time are not from the same seeds like these three and they are coming back more normal.

I wonder if it is telling you it is thirsty. Here, our corn leaves curl when it is dry so that any moisture trickles down the rolled leaves to the base of the corn plant ...

In the FWIW dept ...