Starting Tomatoes From Seeds

Let's get ready to grow!

*We recommend starting your tomato seeds indoors, 6-9 weeks prior to your region's last spring frost.

To calculate when to plant, you will need to find out when the approximate last frost date occurs in your region. Enter your zip code into the USDA Plant Hardiness Zone Map generator here to learn more about your Agricultural Grow Zone, low and high temperatures, first and last frost dates, and lengths of seasons in your area: .

Once you know your average last frost date, plant your seeds approximately 6-9 weeks prior. By the time the last threat of frost has passed or you have a heated structure with workable soil to plant in, you will have established seedlings, with strong root systems, ready to go in the ground. You should aim to plant outdoors 1-2 weeks after your average last freeze to ensure these tender annuals are safe from cold temperatures.


Agriculture grow zone: 6b

Average last frost date for zone 6b: June 1

(Calculate 6-9 weeks prior to June 1)

Seed Starting Date: March 30 - April 16 (6-9 weeks prior to June 1)

There are many alternative methods to sewing seeds- such as different planting containers, different soil mediums, different ways to label, etc. Below is a step-by-step guide that can be tailored to your preferences!


For some of our favorite seed starting supplies, click on the underlined items or visit our Amazon Shop.

Happy Gardening!


  1. Prepare your soil: Pour your seed starting mix, plus a handful of worm castings if using, into a bowl or bucket.

  2. Add a few cups of lukewarm water and mix well, removing any large twigs and breaking down chunks of mix at this time. The mix should be evenly damp, but not soggy wet.

  3. Fill your seed cells to the top with soil and gently press down, to ensure there are no air pockets in the bottom of the cells. After pressing the soil down gently and topping off where necessary, there should be about a 1/4 inch of room at the top of each cell.

  4. Use a pencil to poke 2-3 small holes, side by side, near the center of each cell. The holes should be shallower than the depth of a pencil’s eraser, just under an 1/8 of an inch deep each.

  5. Plant 1 seed in each hole, totaling 2-3 seeds per cell, to ensure germination.

  6. Cover gently, making sure all sides of the seed has come into contact with the soil.

  7. Label and date each pot promptly as it can be very easy to forget what was planted. Tomato seeds can take anywhere from 4-14 days to germinate- all varieties are different.

  8. Fill the drainage tray / water reservoir that your pots will sit in with approximately 1/4 - 1/2 inch of lukewarm water. You want to allow your seedlings to soak up water from the base of the pots like a sponge, rather than pouring water into the soil, which can potentially dislodge your seeds. Watering from the base can establish a stronger root system, prevent dampening off and the surface soil will remain dryer preventing fungus gnats.

  9. Cover with a dome or use a sedan wrap or a clear plastic bag. This will help retain moisture, warmth and speed up germination. Note* Remove the covering a couple of times each day to offer air flow and to prevent algae growth, mold and dampening off.

  10. Place your entire set-up on top of a heat mat or warm surface or at least keep it in a room that stays between 70-85° Fahrenheit. Tomato seeds do not need to sprout.

  11. At the first signs of life, remove the dome or plastic bag promptly, even if only a few seedlings have emerged. At this time, you can also remove the heat mat, but make sure to keep the room itself heated. Side note: The other seedlings will follow shortly if you are keeping the soil moist and the environment warm. Over the next two weeks, if multiple seeds have germinated, you can pinch out the weaker sprouts, cut them at the base with scissors or alternatively, choose to separate the seedlings (also known as “pricking out“). Simply pop them out of the seed cell and gently detangle the roots. It is important to do as minimal damage to the stem and roots system as possible, and replant quickly into a new pot with prepared potting soil. Stout, strong stemmed seedlings with large cotyledons (first set of leaves) are choice contenders to grow out.

  12. Immediately provide light to your seedlings at first signs of life. Place the light directly above your seedlings, as close as possible, without damaging your plants. Keep in mind that if your light emits high heat, they should be distanced further to prevent burning the sensitive seedlings or drying the soil out too quickly. Watch very closely the first few hours to see how the seedlings and soil react. If the soil dries up right away, the light may be too close. If the plants are reaching upward, the light is too far. The goal is to keep your lights close enough so they support your plants growing stout and strong, instead of leggy and weak.

  13. The hours of light you provide to your seedlings is a personal preference, but it is best to offer approximately 14 hours a day at minimum if possible.

  14. Once your seedlings have begun to sprout and are placed under the light, you will turn your fan on low and have it rotate back and forth. It should offer a light breeze, good airflow and gently vibrate the seedlings as they grow. This not only provides airflow and can help prevent dampening off, but also encourages the plants to root deeper, promoting stronger and hardier plants.

  15. Check the moisture of your soil daily. Tomatoes do better in soil that is damp to somewhat dry versus overly wet. Practice a consistent watering schedule by pouring about a 1/2 inch of water into the reservoir that your seed trays sit in when the soil begins to dry. Additionally, mist the the top layer of the soil while your seedlings are germinating to help them emerge from their seed casing. Refrain from pouring water into the soil until your seedlings are larger and have strong root systems.

  16. Your plants will first produce cotyledons, which are the first leaves to emerge on a seedling. After approximately 2 weeks, you will see their first set of TRUE LEAVES emerge, which will look like tomato plant leaves. Some choose to feed their tomato plants immediately after germination, but I prefer to feed after the first true leaves have emerged. It is recommended to mix an all purpose, water-soluble fertilizer at half the recommended strength and feed the seedlings 1-2 times a week simply by pouring it into the reservoir in place of your normal watering.

  17. After around 4 weeks, when your plants are on their second set of true leaves, you will want to plant them into larger containers.

Have fun and enjoy the process. Growing your own food will reward you in many wonderful ways!

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