XVII.OTHER GREENHOUSE CONSIDERATIONS A.Selection structure/covering 1.Initial cost balanced by: –energy cost –labor cost –risk of cover

2.Wholesale greenhouse –ridge and furrow; double layer plastic lower initial cost: heat savings sufficient light less land/unit 3.Retail greenhouse –glass attractive

4.Other considerations –Replace old glass with plastic –Combination houses poly side walls; permanent roof –new roof opening systems natural ventilation

B.Greenhouse Orientation 1.Factors to Consider a.light intensity –reduce shadows b.space available –may dictate orientation

c. maximum light intensity - reduce shadows 1)Northern latitude a)single house E-W b)ridge & furrow houses N-S 2)Southern latitude N-S

C.Other greenhouse structures 1.shade houses reduce light intensity reduce insect problems Materials –Lath –Saran

2.cold frame and hot bed a. use Hardening and growing –bedding plants –vegetable transplants propagation over wintering woody plants

b. construction materials Frame –Wood –Concrete blocks –Transite Sash –Glass –Plastic

c.heating 1)solar 2)steam or hot water –Boiler Pipes around frame 3)electricity –Light bulbs –Heating cable 4)manure

Heating with manure

Heating with exhaust from boiler

Heating with electric cable

Layout of electric cable