Tomato Seed Germination Under Fluorescent Lights

When to Start Tomatoes Indoors

• Start tomato seeds indoor approximately six weeks before the last frost date. A common mistake is starting the seeds too early. Transplant the seedlings once they reach six to eight weeks. Keeping them under lights too long results in a weak plant.

Germination Conditions

• Tomato seeds germinate in either dark or light, but need light as soon as the seedlings emerge. They take anywhere from five to 10 days to germinate, then another four to five weeks to grow to transplant size. The seeds germinate best in warm conditions. Tomatoes germinate between 50 degrees and 95 degrees. A temperature of 80 degrees is best. The lights supply some warmth and bottom heat from a heating pad is desirable.

Lighting

• Lighting is essential once the seedlings germinate. While diffuse sunlight is best for tomato seedlings, fluorescent lights can be used. The bulbs must be as close as possible to the plants without burning them. Approximately 6 inches is best. Keep the lights on for 16 hours each day, turning them on and off at the same time each day. Seedlings that grow tall and leggy need more light.

Water

• Soil in warm conditions, especially under lights, quickly dries out. Keep the soil moist but not wet. Spray the soil with a fine mist or water from the bottom. A running stream of water washes the seeds into bunches. Placing the growing container in a clear plastic bag keeps the soil moist. Remove the bag when the seeds germinate.