get The Very Best Crop From Your Gro-sacks, With Our Specialist Potato Fertiliser.specifically Formulated For Growing Potatoes, Just Mix Some Of This Potash Rich, Pelleted Fertilizer In With Your Compost Or Soil Prior To Planting.a Little Goes A Long Way, A 75g Packet Is Enough For 3 Gro-sacks. the N:p:k Balance Is: 15:21:24.5