The hottest part is the membrane inside to which the seeds are attached. Some of the heat can be removed by cooking, sauteing is the best method for mellowing.
Peppers get hotter when grown under stress.
Once your seedlings are established, its OK to neglect them a bit. They will get back at you for it. Plants may be grown in pots and cut back and brought inside to over-winter in a warm sunny room, or artificial light can be used. This one will make grown men cry, shudder and fall to their knees. We have seen it happen many times, well actually, every time.