By contrast, bell peppers, also called sweet peppers, generally grow languorously and ripen during long, hot summer days when the sun brings out all their flavor. The trick is to harvest this bonanza in late August rather than late September, when cooler nights will rob the peppers of their color and sweetness. Sweet peppers are a bit picky about temperatures. They won't grow at all in cold, wet weather. Mulching helps, especially if mulching with black plastic, which will not only heat the soil, but radiate heat upward into the pepper bush itself.
Moisture also is important.
Peppers must have full sun to produce fruit and for fruit to ripen. There's not a whole lot that a gardener can do if blooms begin to drop off. However, we can be heartened by an experiment conducted by Canadian scientists who actually denuded pepper plants of all open flowers through July and doubled their crops for the year. Most peppers start out green and mature to their ripe color. There are a few exceptions.