I am relatively new to growing and want to know more about the nutrients involved, particularly how they’re sold. Why do some come in three parts, others come in two parts, and there are some brands that are just one part?

When growers are choosing a base nutrient, they will quickly discover there are one-part, two-part or three-part options. Although these base nutrients vary by the amount of parts they come in, they are all designed to provide plants with the essential micronutrients, macronutrients and trace elements needed for healthy plant growth.

The reason why base nutrients are separated into two or three parts on the store shelves has to do with the chemical compounds used in the formulation; more specifically, the calcium source used in the formulation. One-part nutrients use a fully soluble suspension of calcium sulfate. This form of calcium remains stable even when combined (in concentrated form) with the other various elements in the formula. Two- and three-part nutrients always separate the calcium source from other chemical compounds that may cause the nutrients (in concentrated form) to coagulate or otherwise react poorly. This is why the calcium is always found in part A of a two-part formula or in the first part of a three-part formula. When using a two-part or three-part formula, it is important for the grower to dilute part A or the first part of a three-part formula before adding part B or the second part of a three-part formula.

So which is best, a one-part, a two-part or a three-part base nutrient? For many growers, a one-part base nutrient is a good starting point. The ease of use makes this type of formula a popular choice with hobby growers. I have seen comparable results come from one-part, two-part and three-part formulas. In other words, it is possible to get good results when using any of the base nutrient options. Two-part or three-part formulas are great for hydroponic growers or for growers looking for ultimate control over their feeding regimens. All in all, choosing a base nutrient comes down to the grower’s personal preference and what formulation fits best with his or her particular system.