hardening off-getting the plants ready for the garden
it's a good idea to take plants that were grown inside in as greenhouse or in a window and allow them a few hours of suntime to get used to being outside BEFORE you plant them. Try just an hour in the sun and maybe an hour in shade the first day and increase it a few hours each day to help acclimatize them to a harsher environment. Resist the temptation to give them too much direct sun just at first, because they can become sunburned and delay their optimum planting date by damaging the tender plants, Also do not water the foliage while the sun hits them.
I know whereof I speak on this. Also do not try to set them out when the temperatures are not warm enough.
On this as in many things in life caution must rule the day. And following the rules is best.