One of the most common questions I receive about starting seeds is "When do I start giving seedlings fertilizer?"
Although some claim to begin feeding their seedlings with water-soluble fertilizer as soon as they emerge, most University Extensions, including the University of Maine Extension, recommend fertilizing seedlings with 1/2 strength fertilizer once a week after they get their first set of true leaves.
Others mix a weak solution of fertilizer, typically 1/8 to 1/4 strength, and use the solution every time they water the seedlings. This method is convenient, as you can mix the solution and keep it nearby in a container for watering your seedlings.
I'm partial to Miracle Grow, but Bonnie Plants sells a liquid fertilizer that mixes quickly in water. You can also use organic fertilizers, such as fish emulsion, if you prefer. As long as the formula is balanced and contains Nitrogen, Phosphorus and Potassium you will be fine.
Until next time . . . HAPPY GARDENING!