Native to Central America, tomatoes require a relatively long growing season. These warm-season vegetables cannot tolerate frost and suffer when temperatures drop below 50 to 55 degrees Fahrenheit at night. Starting tomato seeds indoors in late winter or early spring provides healthy, robust seedlings for you to transplant in your garden once the weather warms.
Start tomato seeds in flats or individual peat pots 8 to 12 weeks before the last expected frost in your area.
Fill the flats or pots with moist seed starter within 1/4 to 1/2 inch from the top. Mix equal parts peat moss, potting soil and perlite to use as your seed starter.
Plant the tomato seeds to 1/4 inch deep in the soil. Firm the soil down with your hands to secure the seeds and remove air pockets. Spray a mist on the soil to moisten the seeds. Cover the seeds with clear plastic wrap.
Place the seeds in a warm location. Bottom heat is preferred. Place the seeds on top of a water heater, refrigerator or other appliance that provides steady gentle heat. Tomato seeds usually germinate within three to seven days.
Remove the plastic once seedlings have emerged. Move them to bright, indirect sunlight for five days. Gradually increase light until the plants can tolerate full sun.
Keep the soil evenly moistened. Begin a regular schedule of adding water-soluble fertilizer to the soil once the seedlings are 3 to 4 inches high. Mix the fertilizer to 1/4 strength and apply it to the seedlings when watering.
Pinch out the center leaves when the plants are 6 to 8 inches high to encourage compact growth and sturdy stalks.
Transplant to the garden once the danger of frost has passed and the temperature remains above 55 degrees Fahrenheit at night.