Some people go to great lengths to get the hottest peppers around. So what can you do to turn up the heat in hot peppers?
Perhaps the best way to get the most pungent fruit is to plant the hottest cultivars you can get your hands on, assuming that they'll ripen in your area. There is another route, but take care to try it only on a small plot.
Spanish researchers reported that peppers of the cultivar "Padron" were significantly hotter when the plants were drought stressed. It stands to reason. Drought stressed grape vines produce more flavorful wines, and many other fruit, when shy on water, develop more intense flavors.
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The trick here is not to go too far. If you withhold a little too much water, plants will not yield well. If you withhold a lot too much water, they die. Peppers are no exception.
The Spanish research did not report yields, but it's likely that the water stressed pepper plants had lower yields than plants that received sufficient irrigation. So if you skimp on water in hopes of heating up your peppers, best limit the experiment at first and pay attention to yield decreases.