Cucumber seedling wilting

Good Morning Folks.
I'm looking for advice regarding my cucumber seedlings which have wilted.
I have never had this happen before to them all, occasionally a few will do so, however
this time all but one have wilted, after doing really well.
They have been in a heated greenhouse, so well protected from frosty nights and draughts.
This happened to them suddenly.
Any advice or suggestions will be gratefully received.

Hope you all have a great day.

 

I think you need to be able to maintain roughly 20c during the day and above 12c at night for hybrid cucumbers, and preferably a bit warmer.
If not they stand a good chance of getting the wilts, often they don't recover well, if at all.

 

Thank you for your reply, which is very much appreciated.
I have a attached a photo. Kind regards.

 

Thank you for your information regarding temperatures.
My overnight temperatures have been a wee bit lower than 12c.
The seeds are 'Beth Alpha F1' and I also have 'perfection'. I will have another go at sowing in a few weeks and see how they get on. Kind regards.

 

Thank you JWK.
I will see how they get on. I gave some plants to a friend for her 4 year old daughter, she sent me a photo of them and they are doing great!
I put the 2 biggest droopy plants in the heated propagator overnight and they have perked up.
Your advice is much appreciated, thank you for taking the time to reply.
Happy gardening.