Starting peppers under lights allows you to get the plants off to the best possible start in early spring. Outdoor soil is often too cool to grow the warm-weather peppers until early summer. Getting a head start on the gardening season with grow lights ensures that your pepper plants are strong before transplanting them outside and provides them enough time to mature over summer. While pepper plants produce the best fruit outside, they can also be grown indoors over summer with the proper warmth and light.
Fill individual 3- to 5-inch seed-starting pots with a quality potting mix. Water the mix until it is evenly moist throughout.
Sow two pepper seeds in each pot to a ¼-inch depth. Cover the top of the pot with a plastic bag and set it on a germination heat mat set to 65 to 70 degrees F. Germination mats keep the soil at an even temperature necessary for successful germination.
Remove the plastic bag once seeds germinate, usually 14 to 28 days after sowing. Place the seedlings under fluorescent grow lights so the tops of the plants are approximately 6 inches from the lights. Leave the lights on 14 to 16 hours a day.
Water as needed to keep the soil moist but not soggy. Adjust the light as the seedlings grow to maintain the 6-inch distance between the plants and the light tubes.
Transplant the peppers to their permanent pots when they are 5 inches tall and about six weeks old. Fill a 2.5- to 5-gallon pot with potting mix. Lift the pepper seedling by the leaves from its existing pot and plant it to the same depth as it was at in the seedling pot. Water thoroughly after repotting.
Water the plants once a week with a soluble 15-15-15 analysis fertilizer. Water between fertilization when the top 1 inch of soil in the pot begins to feel dry.
Leave the lights on for 14 to 16 hours a day each day. Continue to adjust the height of the grow light to maintain the 6-inch distance between the plant and the tubes. Harvest peppers as they ripen.