What nutes do you use? How much, and how often? What's it's N-P-K?
Are you giving any other additives or micronutes? (Any CalMag Plus, Superthrive, Reverse, hydrogen peroxide...?)
Are you treating for any bugs or other issues that may require you to spray them too much, or gunk-up the leaves?
Did you add anything to the soil before planting or transplanting?
Possible underwatering or overwatering?
Using proper lighting and schedules?

Would likely help if you filled out the troubleshooting form. Just giving bits-n-pieces of info you'll get a wide variety of opinions, over a longer period of time.