Terry here is a Video to watch for you this is how commercial growers do things http://www.eurofresh.com/envirolock/default.asp The company has 330 acres of Glasshouses growing Tomatoes, Cucumbers & Peppers. If commercial growers are to be supplied then these standards are expected. Also have a look at http://www.verticalgrowing.co.uk/Pages/default.aspx This has a Video of the Largest UK glasshouse.