@Mirtha, Here is a great website that lists a bunch of different reasons why your plant could get sick, and has pictures to show what they look like. That should give you an idea of what you need to add/remove to the soil to assess the problem. Also make sure to check your PH levels to make sure your plant is up taking nutrients.
1 and a half weeks from Seed.
This is the best looking plant of the plants that I have
All plants are started Indoor and will get transplanted outdoors in a few weeks into 5 Gal CoCo pots with Drip Emitters.