Ortho

• Ortho liquid fertilizer was the original liquid fertilizer. The molecules of Ortho liquid fertilizer contain a single atom of phosphorus. Because Ortho molecules contain only a single atom, the fertilizer can be readily absorbed by the addition of water. The molecules are simple, provide ready energy and are important for early plant growth.
  
  

Poly

• Poly liquid fertilizer is a concentrated form of Ortho liquid fertilizer. The molecules in Poly contain multiple atoms of phosphorus. In order for this form of liquid fertilizer to be absorbed, it must go through a chemical reaction in order to convert it into the Ortho form. The reaction is created by adding water. Poly must break down into Ortho in order for the molecules to be absorbed by the plant. If the Poly liquid fertilizer does not break down, it will not be absorbed by the plant roots. Polys were created as a way to reduce costs in shipping, reduce the amount of liquid required and provide more plant food per gallon of fertilizer.
  
  

Application

• Both Ortho and Poly are typically sprayed on the soil. Affecting a typical application is soil condition, soil temperature, clay content and proper application methods. Most applicators come with a hose-end sprayer. Some applicators, however, do not allow you to adjust the rate of application or the flow volume per minute. Lightly spray young plants if you use a sprayer that does not allow you to minimize the volume of liquid.