They like fertile, well drained, consistently moist soil. They need plenty of phosphorus (middle number on the fertilizer bag), calcium (they can suffer from blossom end rot without it), magnesium, and sulfur. Too much nitrogen will yield beautiful plants with few fruits, but, of course, nitrogen is important too. I bury a book of matches (without the book), and crushed eggshells in the hole with each plant. These supply sulfur and calcium, respectively. Magnesium (and sulfur) can be supplied with epsom salts. (Mix a bit of salts with water and spray on the plants when blooms begin to appear.)

Other than that, they need warmth. I have good luck growing them in tomato beds. (You do know that the red, orange and yellow peppers are ripe versions of green peppers, right?)