Pasteurization of Greenhouse Substrates

Pasteurization of the soil substrate medium in greenhouse plant cultivation

Soil Steam Fumigation

Steam Fumigation Treatment - is used to kill many of the harmful microorganism and insect populations that can build up in the greenhouse. It is an excellent alternative to chemical fumigation and recommended for the long-term health of the greenhouse environment.

Super-heated steam and water vapor pasteurizes and disinfects the surface and subsurface levels of the soil.

Pasteurization is used to eradicate, or greatly reduce the populations or seeds of, harmful and undesirable organisms. Sterilization is a more extreme method of trying to kill everything in the substrate. Good sanitation practices help prevent a buildup of undesirable organisms in the greenhouse. Pasteurization can be really useful to reduce the buildup of soil pathogenic microbes, weed seeds, insects and insect eggs.

Soil Pasteurization Methods

Prior to steaming the soil is mixed well, fertilizers are added, and the bench is covered with a plastic tarp.

Surface steaming — This may be as simple as heating the soil surface to 200 degrees F for 35 minutes. Excessive steaming can lead to certain molds and fungus outbreaks.
Buried Pipes
Closed Container Steaming - Chamber or Vault steaming where the soil is brought to a special area for steaming.
Chemical Fumigants is not as effective as steaming methods and can be more cumbersome to administer and harmful to crops and workers. The soil must be relative warm for best results. After gas treatment, the soil should be sealed for 24 to 48 hours followed by a 10 to 30 day waiting period before planting. The exact duration depends upon which chemicals are used, how warm the soil is, and how much pasteurization is desired.