1. Greenhouse Management
Growing Media 1
Greenhouse Management

2. Four Functions of a Growing Medium (Root Medium)
Provide a source of nutrients
Provide a source of water
Provide aeration and drainage
Support the plant in the container

3. Types of Media
Soil-based: contains soil
Soil-less: contains no soil

4. Soil-based Media
Require pasteurization.

5. Soil-less Media Contain no soil.
Generally do not require pasteurization.
Available to purchase bagged or in bulk.
May be mixed on site.

6. Bulk bags

7. Soil-based Medium Recipe
A typical recipe used by the greenhouse industry consists of:
1 part soil
1 part sphagnum peat moss
1 part perlite or coarse sand

8. Soil-less Media Ingredients
Various components are mixed together to create a soil-less growing medium.

9. Sphagnum Peat Moss Origin Organic or Inorganic? Role in the Medium
Decomposed sphagnum moss.
Organic
-Water holding capacity.
-Acidic.

10. Composted Bark Origin Organic or Inorganic? Role in the Medium
-Composted hardwood and softwood barks.
-minus ¼ inch diameter.
Organic
-improves aeration and drainage.
-CEC.

11. Composted Yard Waste Origin Organic or Inorganic? Role in the Medium
Composted leaves, grass clippings and brush.
Organic
-Water holding capacity.
-CEC.

12. Coir Origin Organic or Inorganic? Role in the Medium
Waste product from coconut hulls after the fibers have been extracted.
Organic
-Water holding capacity.
-Used like sphagnum peat moss in the medium.
-Can be high in salt; leach before using.

13. Perlite Origin Organic or Inorganic? Role in the Medium
Volcanic rock that has been crushed and heated to high temperatures.
Inorganic
-Improves aeration and drainage.
-Available in different grades.

14. Vermiculite Origin Organic or Inorganic? Role in the Medium
Mica-like mineral that is crushed and heated in a furnace to high temperatures.
Inorganic
-Water holding capacity.
-CEC.
-Available in grades.
-Coarser grades improve aeration and drainage.

15. Calcined Clay Origin Organic or Inorganic? Role in the Medium
Clay heated in a furnace to high temperature.
Inorganic
-Water holding capacity.
-CEC.

16. Rockwool Origin Organic or Inorganic? Role in the Medium
Synthetic fiber made from melted basalt, coke and limestone.
Inorganic
-Ground rockwool can improve water holding capacity.

17. Sand Origin Organic or Inorganic? Role in the Medium
Coarse silica sand.
Inorganic
-Adds weight to the medium.
-May improve aeration and drainage.

18. Pasteurization vs. Sterilization
Kills harmful organisms such as weeds, weed seeds, insects, certain fungi, and nematodes without killing certain beneficial fungi and bacteria.
Sterilization: kills all organisms.

19. Methods of Pasteurization
Steam (aerated to lower temperature)
Electric
Chemical Treatment

20. Steam Pasteurization
Steam Generator

21. Steam Pasteurization
Aeration Blower

22. Cart - 2 cubic yard capacity
Steam Pasteurization
Cart - 2 cubic yard capacity

23. Electric Pasteurization
1 cubic foot capacity electric unit

24. Chemical Treatment
Methyl Bromide
Vapam
Basamid

25. Disadvantages of Using Chemicals
Chemicals are toxic.
Worker Protection.
Proper ventilation prior to use.

26. Preferred Method of Pasteurization
Steam

27. Temperature/Time Parameters for Steam Pasteurization
Text says between degrees F.
Time: minimum of 30 minutes after all the medium has reached degrees F.

28. The End