Chapter 10

Growing Media for Greenhouse Crops

(draft book excerpts)

The production of greenhouse crops involves a number of cultural inputs. Among these, perhaps the most important is the growing media or substrate for growing plants. Growing media are made of engineered materials designed to provide ideal physical and chemical characteristics for the root environment. In greenhouse agriculture, it is important that the substrate has good structural characteristics so it can hold up to frequent irrigation, root growth, temperature change, pH and EC over the life of the crop. At the same time, it has to serve as a reservoir for water and nutrients and be able to allow air exchange between the root system and the aerial environment. It is important that the substrate has low cation exchange Capacity (CEC) so there is better control over fertilizer management and pH of the substrate. Growing media for greenhouses contain a variety of soilless substrates such as peat moss, vermiculite, perlite, shredded coconut husks (coir), or composted materials plus starter nutrients and a wetting agent. Recipes are specially formulated for propagation, specific crops or general use. Field soils are generally unsatisfactory for the production of plants in containers. This is primarily because soils do not provide the aeration, drainage and water holding capacity required. They also need to be pasteurized or fumigated to prevent the development of diseases and germination of weed seeds.

Click on the following topics for more information on growing media for greenhouse crops.

Topics Within This Chapter:

  • Introduction to Growing Media for Greenhouse Crops
  • Properties of Growing Media
  • Growing Media Chemical Properties
  • Cation Exchange Capacity
  • pH
  • Carbon-to-nitrogen Ratio
  • Electrical Conductivity
  • Growing Media Physical Properties
  • Bulk Density
  • Porosity
  • Water-holding Capacity
  • Media Stability
  • Media Column Height and Containers
  • Types of Substrates
  • Organic Substrates
  • Soil
  • Peat
  • Bark
  • Coir
  • Sawdust
  • Animal Manure Composts
  • Crop By-products
  • Inorganic Substrates
  • Vermiculite
  • Calcined Clay
  • Sand
  • Perlite
  • Polystyrene Foam
  • Rockwool
  • Substrate Additives
  • Limestone
  • Wetting Agents
  • Commercial Media Formulations
  • Self-blended Media Formulations
  • Soil Pasteurization and Fumigation
  • Soil Pasteurization
  • Temperature
  • Aerated Steam
  • Soil Preparation
  • Types of Steam Application
  • Soil Fumigation
  • Methyl Bromide
  • Chloropicrin
  • Methyl Iodide
  • Growing Media for Certified Organic Production
  • Certifying Agents
  • Ingredients Allowed for Organic Media
  • Soil
  • Compost
  • Sphagnum Peat Moss and Other Forms of Peat
  • Newspaper
  • Sawdust
  • References