Growing Under Cover
Growing under cover is one of the best ways to maximise your urban food production. Most Urban farms especially in temperate or colder climates maximise their crops with either greenhouses or polytunnels.
There are advantages and disadvantages to both depending on your personal urban farm or circumstances. Greenhouses are more of a permanent structure usually requiring a concrete base. This usually means that greenhouse growers are restricted to growing in pots or small raised beds limiting the advantages from the warm light conditions growing undercover provides. Polytunnels however can be erected over larger growing mediums usually meaning you can plant straight into the soil or larger raised growing beds. This also makes it easier to keep the moisture content of the soil and air humidity optimum.
Generally Greenhouses heat up very quickly and cool down very quickly whereas polytunnels being usually larger maintain a more stable temperature which overall is much better for healthier crops. One of the draw backs of polytunnels however are the covers will need replacing every few years adding inconvenience and cost. Having said that! Greenhouses are more permanent but are much more expensive than tunnels. Unless you have endless financial resources to install a very large green house I would say a polytunnel is the better bet!
The greatest benefit of growing under cover is you have more control over your crops. In urban farms it is always safer to have more crops under cover to reduce exposure to vandalism and pollution. Growing this way also helps you to control bests and maximise the micro climate of urban environments. In temperate climates exotic crops can be grown in summer and more traditional leaf vegetables in winter.
Watch this video from the urban farmer for everything you need to know about growing under cover on your urban farm.