Jobe's Organics Fast Start Granular Fertilizer with Biozome, 4-4-2 Organic Fertilizer Formulated for Seeds and New Plantings, 4 pound bag
I got it on Amazon, but they also sell it in Home Depot and Lowes
I have also used this one which you can dilute in water for feedings once the plants are growing
Jobe's Organics Vegetable & Tomato Fertilizer, 3-1-2 Water Soluble Plant Food Mix with Biozome, 10 oz Box Makes 30 Gallons of Organic Liquid Fertilizer