Temperature problems - if they're in the greenhouse and its sunny, it gets very warm - then overnight, temperatures fall. You need something to even out the temperature fluctuation - leave the doors open when the sun is out, provide a bit of heat on cold nights if possible.

You could even put the plug plants out during the day if it is warm and sunny to start hardening them off. Just make sure you bring them in at night.

Moon grower, Thank you for answering my question in april about my begonia plug plants. They are all thriving very well now and have responded really well to the TLC given to them during the long cold spell in spring.
Mayamurdo

You are welcome Marym.