Peppers are described as sweet (bell) or hot (jalapenos). Pepper heat is rated in Scoville units, named after the man who developed a way to test their hotness. Jalapenos actually rate low on the heat scale.
Light During Germination
Hot chile types like jalapenos need light for germination. A strong light source will increase the number of seeds that germinate.
Jalapenos are sun-lovers that need long days to set fruit. Locate them in a spot in the garden where they get full sun.
Jalapenos need long hours of sunlight to grow and prefer a southern exposure where soil warms up quickly. They need at least six hours of sun per day to grow properly. “They flower and set fruit best when days are eight to 12 hours long,” advises Doug Dudgeon of Brooklyn Botanical Garden.
Even though jalapenos need at least six hours of sunlight daily, they are susceptible to sunscald. “The heat of the sun may burn the side of the fruit exposed,” warns Eldon Everhart of Iowa State University’s Extension. If you live where there are extreme high temperatures, peppers will require some afternoon shade.
Greenhouse Light Requirements
Jalapenos can be grown entirely in the greenhouse or raised to transplant size. Greenhouse-grown jalapenos require at least 13 hours of light and 16 hours of light is ideal.