Well, I see one problem right off which is that you do not have enough calcium in your soil or water for the plants ant the low leaves are sick because of that, or the soil acidity is wrong and they cannot use the calcium that is there.

What is the soil?
Where do you get your water?
What kind of fertilizer?
How big pot, and how tall plant?
What is the temperature and humidity, high and low?
How long have plants lived in the same pot, or how long since last transplant?
Do you know the pH of the runoff out of the bottom of the pots when you water? Read the soil chemistry link in my signature for help with that one.