Nighttime Temperatures for Planting Peppers

Starting Peppers

• The day and nighttime temperatures play an important part from the moment you start your pepper seeds. To germinate, constant exposure to a high temperature of about 80 to 85 degrees Fahrenheit is required. Start the seeds indoors in a seed-starting flat eight weeks before the last spring frost date. Sow them at a depth of 1/4-inch and use a heat mat to provide the ideal temperature. Upon germination, which occurs within seven to 10 days, place the flat in a sunny south-facing window.

After Germination

• When the seedlings have their first true leaves, transplant them to individual 4-inch pots. Then expose them to a nighttime temperature of 60 degrees Fahrenheit and a daytime temperature of 70 degrees Fahrenheit. Once the plants have their third set of true leaves, provide a jolt of cold temperatures to boost flower and fruit production. For about one month, expose the young plants to a nighttime temperature of 55 degrees Fahrenheit by placing them outside in a cold frame. After this, grow the plants at 70 degrees Fahrenheit during the day and night until it's time to transplant.

Transplanting

• Transplanting should only occur after the soil warms up to 60 degrees Fahrenheit and the nighttime temperature is above 50 degrees Fahrenheit. The ideal temperature to grow peppers is between 60 and 70 degrees Fahrenheit at night and between 70 and 80 degrees Fahrenheit during the day. If your plants are exposed to nighttime temperatures below 60 degrees Fahrenheit, the blossoms may drop. High daytime temperatures of 90 degrees Fahrenheit or more can have a similar effect.

Protection

• To protect your pepper plants from an unexpected cold spell, use row covers. Row covers come in a variety of materials that offer different degrees of frost protection. The heavier the material the more protection is offered. The covers drape over the plants like a tent and shield them. When the weather warms up, remove the covers to avoid overheating the plants and triggering blossom drop. Consider using row covers in combination with black plastic, which speeds the soil-warming process, to give your peppers an earlier start.