Organic Onion Fertilizer 3 lbs. Organic Onion Fertilizer All-Natural & Non-GMO Sourced Onion Fertilizer (3-4-3). 3 lbs. will feed 240 onion plants for an entire season. Guaranteed to increase yields, size, health and vigor of your onion plants. Derived from: Fish Bone Meal, Gypsum, Blood Meal, Alfalfa Meal, Sulfate of Potash & Feather Meal.