Cutting Edge Solutions Uncle John's Blend SP 0-0-27Uncle Johns Blend SP 4 0 27 combines essential trace micronutrients such as Manganese (Mn), Zinc (Zn), Iron (Fe), and Sulfur (S) along with the essential primary nutrient Potassium (K) to enhance the genetic potential of plants. Uncle Johns Blend SP 4 0 27 is the Soluble Powder(SP) version of the original liquid Uncle Johns Blend. Uncle Johns SP 4 0 27 is recommended as a supplement in all stages of plant growth, but is most critical in the flowering