What is the Best Fertilizer for Lettuce? Greenway Biotech, Inc. Blood Meal Fertilizer 13 0 0 Organic Fast Release Nitrogen for Gardens Greenway Biotech Greenway Biotech, Inc. MasterBlend Lettuce Formula 8 15 36 Fertilizer Buy from PowerGrow PowerGrow Systems & Utah Hydroponics Amazon.com : Greenway Biotech, Inc. Lettuce Fertilizer 8 15 36 Powder Water Soluble with Chelated Micronutrients for Lettuce Kale Spinach Microgreens Helps Prevent Tip Burn Hydroponics or Soil 1 LB : Patio, Lawn & Garden Understanding NPK: The Three Key Nutrients in Fertilizers When you look at a fertilizer label, you'll often see three numbers. These numbers stand for nitrogen (N), phosphorus (P), and potassium (K). Each