Leathery leaves of box car willie
I live in Singapore, and it's at least 32C/ 90F in the daytime with high humidity; and around 27C/80F at night.
I'm experimenting growing box car willie and virginia sweets in containers. The plants are placed out under full sunlight.
About 4 days ago, I noticed that all the 7 week old box car willie plants have developed leathery leaves at the lower part of the plant(some leaves have curled/scorched looking edges), save for the new shoots growing out.
The 5 week old virginia sweets leaves don't seem to show any leathery leaves symptoms.
We'd also experienced rain for 3 consecutive days over the past couple of weeks.
Appreciate if someone could tell me if it's normal for the box car willie plants to have the leathery leaves. What should I do? Should I place them in the shade to grow?