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Hydroponic Nutrients v. Additives

Choosing the "food" that your plants get and don't get comes down to the nutrients you decide to use. Whatever form of nutrient you need, you’ll find many choices in the GrowersHouse plant nutrient store on these pages.

Hydroponic nutrients come in two main categories:

  • Base nutrients. These are the main source of vital elements, including minerals and vitamins.
  • Additives. These supplements should be applied only in small amounts as needed.
    • Most base nutrients have multiple parts, denoted for vegetative growth or for the blooming—the flower—stage. Additives typically come in smaller amounts and can be applied when your plant is showing deficiencies in a certain element. Additives also are used to arouse certain characteristics in your plants, such as taste, flower size or even root growth.

      Matching Nutrients to Media

      Always match the appropriate form of grow room nutrients to your growing medium, whether it is soil, coco, or inert materials such as Rockwool or Hydroton clay pellets for hydroponics. Most big brands come in forms to work with any one particular type of media, while others are labeled universal because they work with all media.

      Nutrients for use in soil are typically made to supplement and eventually replace the nutrients originally available in the soil mix. Nutrients for coco and hydroponics are all the nutrients your plants will ever receive, so they should be applied throughout the life of the plants. Many brands come with two parts—one for vegetative growth, the other for flowering.

      Base nutrients

      Base nutrients come in organic and synthetic options:

      • Organic Nutrients may contain larger particulates that can clog pumps, tubing, sprayers and misters. That makes them more appropriate for use in soil, soilless media, and coco coir where the nutrient solution is not reused or recirculated.
      • Synthetic Nutrients make up most of the available hydroponic grow nutrients. Often they can also be used in coco coir and soil, depending on the brand and formula. (You know the drill: Read the label.)

      All nutrients come labeled with numbers that are the ratio of nitrogen, phosphorous and potassium (N-P-K), always in that order. The numbers represent the percentage of respective nutrients that are immediately available to the plant. Synthetic nutrients for hydroponics typically have higher numbers because the nutrients they contain are immediately available, while the nutrients in organics take longer to break down for absorption by the plant.


      Additives come in many formulas, covering the entire plant's life from root growth to flower sweetening. Each has its own purpose and usage, often keyed to one or more plant phases:

      Importance of pH Levels

      The pH level of your medium is highly important at all times because plants are able to take up some nutrients only in certain pH ranges. Remember, no nutrients would mean no growth.

      For hydroponics, keep your pH at 5.5 to 6.5; for soil, keep pH at 6.2 to 7.2. Use pH Up and pH Down to bring water and nutrient solutions to the proper pH. You can determine pH levels quickly, easily and affordably with a pH tester or meter.

      Need Help Choosing Your Nutrients? Get more details and tips in our Nutrient Buyers Guide.