Rima,

Bitter Melon is a tropical plant. It does not like cold weather. While it may not die at 40 degress, it will not be happy at all. If it's going to be cold for a long time, bring it in. Where did you purchase seedlings?

Bitter Melon performs best between daytime temperatures of 82ð - 95ðF and night temperatures between 69ð-77ð. It requires more heat than the other gourds to produce maximum yield..

Here is a link that might be useful: How to Transplant with Success

Most plants will be a little wilty after transplanting until their roots get reestablished. Are yours perking up yet? Often it only takes a couple of days.

I usually transplant late in the day so they don't have the heat of the sun to contend with for the first few hours. And I water them well, of course.

Good luck.

Jim

Cover the plants with pots (up side down ) haveing holes for drainage,for few days.