About  2 weeks before you are ready to transplant, you will need to get your new plants use to their new growing arena-THE OUTDOORS!. With the new outside sun, wind and cool nights these seedlings have alot to adjust to.  Start out by setting the new seedlings outside in a protected area, for an hour or two each day and then gradualy increase their exposure until the transplant date.  Be aware not to over do it the first few days, as they may dry out fairly quickly outdoors, then what they were use to in their warm and cozy home indoors.