Careful planting them near other, milder varieties of pepper ... this may sound strange, but I've eaten ordinary green peppers out of my garden that apparently cross pollinated with a nearby row of habañeros - surprise - hot!!!
Been there, done that!!!!!
I learned that lesson the hard way more than 10 years ago. My hot and sweet peppers are seperated by about 150 feet. And I have my hots in rows, habaneros at one end and jalapenos at the other, and in between they are in descending order of heat.