Leaves turning yellow and reddish on some

[AllNewToThis]

Hi, I am hoping someone can help. My leaves are turning yellow/reddish on my outdoor plants just like in the fall. I haven’t changed anything with regards to watering or nutrients. Can anyone help. Do I need to trim off the yellow leaves or leaves them On to fall off on there own? As everyday there seems to be more and more. I live in southern Ontario Canada.

 

[Grownsince95]

I would really defolliate that and get some airflow in there. And yes the yellow leaves can go as well as any other big lower fan leaves. Hard to tell from pics but some leaves look like there's powdery mildew spots?
Some yellowing and color changes are normal as the plants get deeper into flower though.

 

[blit98]

they look hungry to me but im new...

 

[Beachwalker]

they look hungry to me but im new...

+1