[Stiofain]

This may sound like a daft question but here goes. What are the advantages of adding a heater to a tunnel over winter, at least for particularly cold period. Is it a case that there will be little or no growth during cold periods without heating the tunnel?

[tagwex]

Not daft at all. But it would depend on what you want to grow as some veg can be sown in autumn, they will go dormant over the winter and start growing again in spring so you therefore have a headstart. Also you could start a month or so earlier in the spring time and again get a headstart with some crops. Sowing outside is mostly done in April/May whereas the heated tunnel could start in March.