I have just put up an unheated polytunnel, is it too cold to start squash and courgettes off? The packet says they need 25 degrees C, which it is during the day, but its very cold at night.
Have some blue banana, Waltham butternut, Cousa courgette and ball courgette.
I put some Crown Prince in the poly this year - it took about two week to germinate. I covered the pots with a bell cloche and covered the whole try with bubble wrap.
If you can provide a bit of extra local insultation, I think you should be OK
Aha, forgot about good old bubble wrap. Have several metres of it at home!
Here I would still think it too soon... :-\
Too soon XX Jeannine
One can only try....I have just one courgette plant to try if I can get few extra early ones out of it...but squash..hmm..and why not... ;D
It is OK if you are prepared to lose plants if the weather turns cold, have some back-ups and remember that they can be sown as late as May.
It is however debatable how much advantage you get from early sowing/planting.
A good rule of thumb is that they do not like a minimum temperature of less than 10C.
You can see results on :-
http://allaboutallotments.com/Butternutsquash.html