METHODS OF SECURING WIDE POLYTHENE SHEETING TO GREENHOUSE STRUCTURES USED FOR COMMERCIAL GROWING

With one notable exception, every type of Greenhouse Structure covered with flexible plastic sheeting requires a rigid or semirigid support to which the plastics is secured. The exceptional type is of course the air-supported or "Bubble" greenhouse which is the subject of another paper in this conference.

This paper examines some methods of fixing plastic film and illustrates some recent greenhouses in England which are covered with polythene films in seamless widths of 36 ft. (12 metres) wide.

Polythene film in common with most other thin translucent films weakens slowly on prolonged exposure to sunshine and the commercial grower is concerned not only with the initial cost of a greenhouse, but also with the recurring cost of recovering it at intervals. This cost is divided between the cost of the plastic sheeting and the labour cost of replacing it. A primary virtue of polythene sheeting is that it is cheap. Any fixing method which reduces the labour cost of recovering is of great importance. Wide seamless sheeting used in conjunction with synthetic or wire netting appears to offer a grower an economical method of covering his greenhouse structures.