Heirloom tomatoes are as close to "good old fashioned" tomatoes as you can get. They are tomatoes that have not been part of the hybrid process of genetically mixing or breeding tomatoes to achieve a specific goal (such as square tomatoes or tomatoes that last longer on the grocer's shelf). Many gardeners feel that heirloom tomatoes have a taste that is superior to that of hybrid or store-bought tomatoes. There are no special steps involved in growing heirloom tomato seeds.
Fill a growing tray with a commercial starting mix. Dampen it thoroughly and lightly. Press it down to remove air.
Press your heirloom tomato seeds into the growing mix approximately 2 inches apart. Push them in no more than 1/4 inch, then cover with growing mix. Press down lightly on the growing mix.
Dampen the mix well, but do not make it soggy. Too much water could cause fungal growth.
Place the growing tray inside a large plastic bag but leave the end of the bag untied so that some air can circulate around the growing tray.
Put the bagged growing tray in a warm, well-lit location that is out of direct sunlight. Keep the temperature between 70 and 80 degrees F.
Check the growing tray every couple of days to make sure that the growing mix is damp. Add water as necessary, but only to keep the growing medium damp. Your seeds should sprout within 5 to 10 days.
Remove the plastic bag once the seeds sprout and allow the tray to get full direct sunlight for up to four hours each day until the plants are 2 to 3 inches tall, at which point they can be transplanted to the garden into a mixture of 50/50 garden soil and humus.