I started my tomatoes and peppers indoors last year, but moved them under my hoop houses once they sprouted. I opened the ends first for several days, then moved the plants out to a place that gets sun about half the day (remember that your plastic blocks some light, so they can still get shocked by full sun) and near the house for wind protection. I had very healthy, sturdy seedlings, though I did have a bit of phosphorus deficiency, which means I should have let it warm up a bit more before moving the plants out.