You need to harden them off by putting out during the day and taking back into the greenhouse at night for a week or more. Depending where you are in W Yorkshire this could be now or another week or so before you start. You need to make sure that all risk of frost is past or they'll not survive.

Hi, if you have a cold frame, I would suggest you transfer them from the greenhouse to the cold frame, in about 2 weeks time, leave the top open through the day, and for the first night close the top, second night leave it slightly open, increase the opening each night, until you can leave it completely open all the time, by this time we should be into june, and the risk of frost passed, { hopefully}, Derek.

hopefully Derek!

LOL, Mg, Derek.