Greenhouse Substrates and Fertilization

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Everyone seems to be searching for the ideal plant mix. The criteria are simple: make a mix with good aeration, that doesn’t dry out too quickly, can be used in all cell sizes, contains all the nutrients necessary, can be used for all species of and stores indefinitely. All that is needed is a substrate that is not affected by other forces in the greenhouse; a mix that does not change with cultural practices. Obviously, trying to make the mix totally responsible for air, water and nutrition will be unsuccessful. A better strategy is to integrate the mix into a production system that addresses substrate aeration and water retention as well as plant nutrition and fertilization requirements.


  • Aeration and water retention
    • The substrate
    • The container
    • Substrate handling
    • Watering practices
  • Nutrition and fertilization
    • Incorporated fertilizers
    • Substrate pH
      • Preplant materials
      • water alkalinity
      • Fertilizer acidity/basicity
      • Species effect on substrate pH
      • Strategies to control pH
    • Postplant fertilization
    • Fertilizer formulations
    • Nutritional monitoring
      • Collecting a substrate sample for laboratory analysis
      • Preparing a subtrate extract for in-house measurement of pH and EC
      • Collecting a plant tissuesample for a foliar analysis.
      • Collecting a water or fertilizer solution sample for a laboratory analysis
      • In-house analysis of water and fertilizer solution pH and EC
      • In-house analysis of water alkalinity
      • Interpretation of test results


D. A. Bailey
W. C. Fonteno
P. V. Nelson
North Carolina State University