How to Start Tomatoes from Seed

newly sprouted tomato seedlings, tomato seedlings, tiny tomato plants

If you love tomatoes in any form and can garden, you’ll probably want to grow some yourself. Tomatoes are one of the most rewarding things to grow in a vegetable or container garden, and if you find you really enjoy growing tomatoes, you’ll eventually want to try growing them from seed. Some good reasons grow them from seed are found here.

What You Need To Start Tomatoes from Seed:

  • Some kind of tray or pot in which to plant the seeds. I often use cut off coffee cans or, for larger plantings, an inexpensive plastic dishpan with  few holes drilled in the bottom.
  • “Soiless Growing Medium”  is a fancy word for “potting soil. Don’t use garden soil unless you can afford to lose you little plants. Regular “dirt” comes with lots of pathogens and even some “critters” which can harm your seeds and plants. Something about the artificial environment of having that soil “disconnected” from the rest of the garden, often brings out the worst in these things, killing the small plants, so check with a good garden center for a good seed starting medium.
  • Light: The growing plants require the minimum equivalent of 6 hours a day of FULL SUN. This can be a challenge in the winter time. Grow lights may be necessary if you don’t have a good southern, eastern or western exposed window sill available. (Southern is the best.)
  • Heat: Germinating tomato seeds require warmth. They should be started at a temperature between 70 and 90 F. Once germinated they will be okay at 60 F, but tomatoes simply LOVE warmth. For a small flat, one might try setting it on a heating pad until the seeds germinate.
  • Time: Count on 5 days to 3 weeks time for the seeds to germinate and sprout. Cooler temps will slow this process. Older seed may take considerably longer to germinate than fresh seed. The ideal is to start tomato seeds 6 to 8 weeks before you want to transplant into the garden.

How to Start Tomato Seeds:

  • Fill the pot/tray to within an inch of the top with good quality soiless potting soil.
  • Saturate the potting soil and let drain until barely dripping.
  • Drop seeds on the surface of the soil, giving them about 1/2″ to an inch space between them.
  • Either use a knife tip to push the seeds down about 1/8″ to 1/4″ into the soil, or sprinkle that much soil mix on top of them, misting to moisten it.
  • (Optional) Place plastic wrap over the pot/tray, to conserve moisture. Be sure to remove the plastic wrap when the first tiny plants emerge.
Starting tomato seeds, planting tomato seeds, sowing tomato seeds
A dishpan makes a nice seed starting tray.

What to do after the seeds germinate:

  • Be sure they get plenty of light and air movement, to prevent fungal problems and promote healthy growth.
  • Transplant the seedlings into fresh potting mix once they’re up about 3″.
  • Fertilize with a dilute fertilizer to promote constant, steady growth.
  • Try to keep them above 50 F.
Tomato seedlings, pepper seedlings, vegetable seedlings.
This is the same tray, about 2 1/2 weeks after planting.

Before Transplanting into the Garden:

Make sure that they have been gradually introduced to real, unfiltered sunlight. Even real sunlight, streaming through a glass or plastic window, will lack the UV rays which can cause sunburn. If suddenly left exposed to naturally occurring  UV light the little plants will bleach out and die. They must be hardened off before they can be put outdoors full time. To do this one needs to give the plants a small amount of exposure to natural sunlight, in the time period of a day, gradually building it up.

Blog post: Four Tips for Planting Tomatoes

Green Country Seed Savers Post on Starting Tomatoes from Seed

Related article: Why Grow Tomatoes from Seed


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