Polytunnel

If you have a plastic tunnel what would it mean for annual flowers? i.e. could you plant them now then put them out as soon as they are suitable and have flowers earlier - how many months early?

 

Yes you can sow then earlier, and yes they will flower earlier. But you need enough heat in the greenhouse to get them to germinate, keep them alive, and keep them growing (and you need light too, which restricts how eary you can start, to some extent)

The greenhouse alone will give you some gain, but if you want to start even earlier you'll need some heating - a gas-fired greenhouse heater would do the trick, and you'd only need it for a few months of the year.

Half hardy annuals, grown in greenhouses for transplanting outside later, tend to be sown Feb - Mar (earlier if you have the heat in your greenhouse, and perhaps a propagator for germination (or germinate them in the airing cupboard or somesuch ...)

 

A polytunnel is a different proposition than a greenhouse they are more expensive to heat the temperature is suject to instant change they are difficult to ventillate and keep at a constant temperature,having said that they will protect your plants from the wind and rain you would need to start off your plants in the manner that Kirsten has descibed because polytunnels are difficult to insulate and heat what I have done with mine is build a smaller tunnel inside this holds 3-4c higher temp.than the rest of the tunnel,under the bench inside the second tunnel there is a small tube heater set to give frost protection.