'Local' is commonly assumed to be best for the environment, but when it comes to heated glasshouse crops this is often not the case. Even with the help of tunnels or glass, without heating tomatoes can only be harvested in this country from July to October. The bulk of the crop is harvested in August and September; a very short season even for the most die-hard seasonal eater.
Intensive, highly professional hot house producers plant their crops in heated greenhouses in January or February so they can harvest from March or April through to November or December. This produces prolific yields over a long season but only at the expense of huge amounts of heat which is normally produced by burning gas or oil. For every kilo of tomatoes picked two to three kg of CO2 are released into the atmosphere.