Name 5 types of greenhouse covering materials and describe.
Glass: various pane sizes, breakage, high cost, lasts long, heavy
Plastic film: polyethylene, polyvinylchloride, 2-8 cm thick, single and double thickness, longevity a problem
Flexi plastic sheeting: acrylic, polycarbinate, shatter-resistant, filter heat transfer
Fiberglass: less used than any other
Saran netting: woven/knitted, various degrees of light transmission