Why Are My Four O’clock’s Leaves Turning Yellow And Falling Off?

Question

They have been really healthy, however our region was hit with catastrophic wildfires. Due to the smoke, several of my plants aren’t fairing well. Could it be the same thing as my other plants??

• 
• 

Answer 1

It could be due to smoke, which can clog the plant's tiny pores used to absorb carbon dioxide. Smoke can also destroy chlorophyll, thereby reducing photosynthesis. Try rinsing the leaves with water, and applying fertilizer to give it a boost.
I would also examine the leaves for insect pests (though smoke can deter them).

https://www.gardeningknowhow.com/ornamental/flowers/four-oclocks/four-oclock-plants.htm