If starting your own transplants, sow seeds into plastic plug trays with 50-72 cells per tray filled with a good soilless mix. Adequate light is essential to produce a quality plant. Supplemental light may be necessary when growing transplants in the winter and early spring. Cool white fluorescent lights positioned 2 to 3 inches above the plants for 14 to 16 hours per day will ensure large and healthy seedlings. Optimum germination occurs at 86°F, and the use of heating mats will increase speed of germination and the percentage of seedlings that emerge. Optimal temperatures for plant growth are 75°F during the day and 65°F at night.
Allow 8 to 10 (pepper and eggplant) or 6 to 8 (tomato) weeks for growth of transplants depending on greenhouse temperatures. Transplants should have 5 to 7 mature leaves and a well-developed root system. Irrigate plants regularly to avoid excessively dry soil. Apply a complete soluble fertilizer (20-20-20) diluted to 100 ppm once or twice a week. Gently brushing the plants each day or exposing them to wind helps make the plants stocky and strong. Condition or “harden off” transplants for a short time each day by exposing them to cool temperatures (60-65°F for eggplant and pepper, and 50-60°F for tomato), starting one week before transplanting. This prepares the plant for fluctuating light and temperature conditions prior to transplanting outdoors.