I have recently helped my daughter plant her first raised bed garden in New Jersey two and a half weeks ago. She has tomatoes zucchini peppers and herbs. She has noticed some of the plants have a couple of yellowing leaves on the veggies. The soil supposedly feeds for up to three months. I have always thought yellowing leaves mean to much water and brown are dying leaves. Not sure if it needs an extra nutriant. Any help would be appreciated in know when plant leaves turn different color and why?