Time to Start Tomatoes From Seed!

As thoughts turn to vegetable gardening in late winter and early spring, many of us want to start some vegetables indoors. Tomatoes, of course, are often the first choice! Starting tomatoes from seed is more work than buying transplants, but can be a very satisfying and rewarding way to try new, unusual and tasty varieties, while saving your money. It may even provide an earlier harvest!

To begin, plan your garden in the winter, review the seed catalogs that start arriving in January, and order seeds to arrive in time for planting indoors in your area. Consult the Virginia Cooperative Extension Home Garden Vegetable Planting Guide to help you plan for planting guidelines, frost dates and to estimate the number of plants needed for your garden size.

Purchasing your own seeds from catalogs, online sources, a seed savers exchange or fellow gardeners offers a wide range of fruit characteristics (beefsteak, cherry, paste, grape), as well as a choice of hybrid or heirloom tomatoes. Determinate or indeterminate tomato types provide options for harvesting over a 4-5 week period or continuing for the entire growing season. Catalogs and seed packets will also indicate which varieties are resistant to tomato diseases (Verticillium Wilt, Fusarium Wilt, etc.). Just be sure to buy high-quality seed from reputable seed companies or other sources.

Be sure to time your seed starting by sowing seeds five to seven weeks before the last average frost date. In Central Virginia, the average last frost date for plant hardiness zone 7a is April 15 to 25. This makes March a good time to start those tomato seeds growing in the local area. A common mistake is to start seeds too early, which can result in tall, leggy, weak plants that do not transplant well. A good source to calculate when to sow seeds is Johnny’s Seeds-Starting Date Calculator.

Once ready to start, you will need:

  • a south-facing window or grow lights (LED or fluorescent)
  • seed starting medium (sterile, soil-less, fine and lightweight texture)
  • pots, soil blocks or other containers (clean, 2-3 inches deep)
  • tray with cover or plastic wrap
  • tomato seeds
  • spray bottle for water
  • a warm place or heat mat (optional)
  • fan or other way to circulate air

 

Then, the planting begins:

  • fill a 2” pot or other small container with drainage hole with pre-moistened seed starting medium to within ¾” of top
  • do NOT use garden soil or potting soil
  • add 2-3 seeds per container or sow in rows ¼” deep
  • cover lightly with the seed-starting medium and place in a tray
  • label the tray or the individual plants if you have multiple types in one tray
  • water gently with the spray bottle until moist
  • put on cover or plastic wrap
  • place in a warm place or use a heat mat
  • keep moist, but not soggy
  • record planting date and plant name
  • room temperature should be above 55-60º F and soil temperature around 70-80º F
  • seedlings should appear in 7-10 days

Once the seedlings appear with the first set of leaves, called seed or cotyledon leaves:

  • remove plastic wrap and place in south-facing window or under grow lights for 12-18 hours a day, with lights 1-2” above plants
  • water from bottom, so plants soak up water, without having pots sit in water for long periods of time
  • when seedlings have 1-2 sets of true leaves (appearing after the seed leaves), consider transplanting to 3-4” containers
  • adjust lights as plants grow, and rotate plants
  • have fan at low setting to circulate air, which will develop stronger stems
  • fertilize at half strength after first true leaves appear once every 10-14 days.

Then prepare plants for transplanting when 6-10” tall by hardening them off, as follows:

  • decrease watering and fertilizing 2 weeks before transplanting
  • expose plants to filtered sun, then direct sun, light wind and cooler temperatures during the day over 5-7 days

Transplant them to your garden when the soil is warm and all danger of frost is over. You will be off to an outdoor tomato gardening experience that will likely pay off with beautiful and delicious tomatoes for your table. The references below will guide you on your tomato growing journey.

References

“Planning the Vegetable Garden,” Alex Niemiera, Virginia Cooperative Extension, Publication 426-312, 2015.

“Starting Seeds Indoors,” University of Maryland Extension, Home & Garden Information Center.

“Successful Tomatoes from Seed,” Susan Marquesen, Penn State Extension, Allegheny County Master Gardener, 2019.

“Tomatoes,” University of Maryland Extension, Home & Garden Information Center.

“Tomatoes,” Diane Relf et al., Virginia Cooperative Extension, Publication 426-418, 2016.

“Tomato Love!”, Colleen Kennedy & Dona Lee, Virginia Cooperative Extension, Master Gardeners of Northern Virginia, 2020.

“Virginia Home Garden Vegetable Planting Guide: Recommended Planting Dates and Amounts to Plant,” Alex Hessler, Virginia Cooperative Extension, Publication 426-331.