+1 on fertilizer burn. You don't need to be feeding small plants like that, and if you do use very small doses. Since you have them in pots, you may want the flush the soil. Nutrient salts get trapped in the soil and can keep hurting the plants. Flush with 2-3 gal of water per gal of soil. After that just feed if they look like they need it and start with small doses then work your way up until you get a feel for what they can handle.