You can grow new tomato plants from seeds inside the fruit or from stem cuttings taken from a living plant

Growing tomatoes from seed is the most common method and gives you the widest choice of varieties. You harvest seeds from ripe tomatoes, dry them, store them, and plant them indoors 6 to 8 weeks before your last spring frost. Growing from cuttings is faster — you take a 6-inch stem from an existing plant, root it in water or soil, and transplant it once roots form. Both methods work, and which one you choose depends on whether you want variety or speed, and whether you already have a healthy tomato plant to take cuttings from.

The seed method takes longer overall but costs almost nothing and lets you grow any variety you can find seeds for. The cutting method skips the seed stage entirely, so you can have a flowering plant in 4 to 6 weeks instead of 8 to 12. If you are new to growing tomatoes, either method is straightforward — seeds need warmth and light, and cuttings need moisture and humidity.

Key Takeaways

  • Seeds from store-bought tomatoes often come from hybrid plants and will not grow into plants that match the parent fruit, so save seeds only from heirloom or open-pollinated varieties if you want predictable results.
  • Tomato seeds need to be fermented in water for 2 to 3 days to remove the gel coating that prevents germination, then dried completely before storage.
  • Start seeds indoors under grow lights or on a sunny windowsill 6 to 8 weeks before your last frost date, keeping soil warm (70 to 80 degrees Fahrenheit) and moist but not waterlogged.
  • Stem cuttings root in 1 to 2 weeks in water or moist soil and skip the seed stage entirely, so you can have a flowering plant in 4 to 6 weeks instead of 8 to 12.
  • Hardening off — gradually exposing seedlings to outdoor conditions over 7 to 10 days — prevents shock and leaf damage when you move plants outside.

Saving and preparing seeds from ripe tomatoes

To save seeds, choose a fully ripe tomato and cut it in half. Scoop the seeds and gel into a small jar or cup. Add a little water — just enough to cover the seeds — and let it sit at room temperature for 2 to 3 days. The fermentation breaks down the gel coating that naturally prevents seeds from sprouting inside the fruit. You will see mold on top; this is normal and part of the process.

After fermentation, rinse the seeds in a fine strainer under running water, rubbing them gently with your finger to remove all gel and mold. Spread them on a paper plate or coffee filter and let them air-dry completely in a warm, dry place away from direct sun. This takes 1 to 2 weeks. Once completely dry, store seeds in a paper envelope in a cool, dark place — a basement, closet, or refrigerator works well. Tomato seeds stay viable for 4 to 5 years when stored this way.

One important note: seeds from hybrid tomatoes (most supermarket varieties) will not grow into plants that produce the same fruit. If you want seeds that will grow into tomatoes matching the parent fruit, save seeds only from heirloom or open-pollinated varieties. The seed packet or plant label will tell you which type you have.

Starting seeds indoors under lights or on a windowsill

Start seeds indoors 6 to 8 weeks before your last spring frost date. You can find your frost date by searching "[your city] last frost date" online — it varies by region and changes year to year. Fill seed trays or small pots with seed-starting mix (a light, sterile blend sold at garden centers), moisten it, and plant seeds about a quarter-inch deep. Tomato seeds germinate best in warm soil, ideally 70 to 80 degrees Fahrenheit.

If you have a grow light, place the tray directly under it about 2 to 3 inches from the bulbs. If you are using a sunny windowsill, choose a south-facing window and rotate the tray every few days so seedlings grow straight instead of leaning toward the light. Keep the soil moist but not soggy — soggy soil causes damping off, a fungal disease that kills seedlings at the soil line. Seeds usually sprout in 5 to 10 days.

Once seedlings emerge, they need 14 to 16 hours of light per day. If they look pale or stretch toward the light, move the light closer or move the tray to a brighter window. When seedlings develop their first true leaves (the second set of leaves that appear), thin them out or transplant them into individual 4-inch pots filled with potting soil. This gives roots room to grow and prevents crowding.

Hardening off seedlings before moving them outside

Seedlings grown indoors are tender and will wilt or turn purple if moved directly into outdoor sun and wind. Hardening off — gradually exposing them to outdoor conditions — takes 7 to 10 days and prevents this shock. Start by placing seedlings in a sheltered spot outdoors (a porch or against a wall) for 2 to 3 hours on the first day, in dappled shade or morning sun only.

Each day, increase the time outdoors and the amount of direct sun they receive. By day 7 or 8, seedlings should be outside all day. On the final days, leave them out overnight if temperatures stay above 50 degrees Fahrenheit. Once they have been outside overnight without damage, they are ready to plant in the garden or larger containers. Skipping this step often results in sunburned leaves and stunted growth, so it is worth the extra week of attention.

Growing tomatoes from stem cuttings

Cuttings are a faster way to clone an existing tomato plant. Choose a healthy stem 6 to 8 inches long from the top or side of the plant, cutting just below a leaf node (the bump where leaves attach). Remove all leaves except the top 2 or 3, and strip any leaves that would sit below the waterline if you are rooting in water.

To root in water, place the cutting in a glass or jar filled with room-temperature water, and set it on a bright windowsill out of direct sun. Change the water every 2 to 3 days to keep it oxygenated. Roots usually appear in 1 to 2 weeks. Once roots are at least half an inch long, transplant the cutting into a small pot of moist potting soil.

To root in soil, dip the cut end in rooting hormone powder (optional but speeds rooting), then insert it into a small pot of moist seed-starting mix or potting soil. Cover the pot loosely with a plastic bag to keep humidity high, and place it on a warm windowsill. Check soil moisture every few days — it should be moist but not waterlogged. Roots form in 1 to 2 weeks. Once you see new growth at the top, remove the plastic bag and treat the cutting like a young seedling.

Transplanting seedlings and rooted cuttings into the garden

Tomato seedlings and rooted cuttings are ready to plant outside once they are 6 to 8 inches tall, have several sets of true leaves, and have been hardened off. Plant them deeper than they were growing in their pots — tomatoes can develop roots all along the buried stem, which strengthens the plant. Bury the stem up to the lowest set of leaves if the plant is tall and leggy.

Space plants 24 to 36 inches apart in full sun (at least 6 to 8 hours per day). Tomatoes need well-draining soil rich in organic matter. At planting time, add compost or aged manure to the planting hole. Water deeply after planting and keep soil consistently moist — about 1 to 2 inches per week from rain or watering. Inconsistent watering causes problems like blossom-end rot and fruit cracking.

Troubleshooting common problems with seedlings

Leggy seedlings (tall, thin, pale) mean insufficient light. Move the light closer to the tray or move seedlings to a brighter window. Increase light to 14 to 16 hours per day if you are not already doing so. Leggy seedlings can still be saved — bury them deeper when transplanting to the garden, and they will develop roots along the buried stem.

Damping off (seedlings collapse at the soil line) is caused by overwatering and poor air circulation. Let soil dry slightly between waterings, and run a small fan on low speed near the seedlings to improve air movement. Once damping off starts, it is hard to stop, so prevention is key. Use sterile seed-starting mix rather than garden soil, which can harbor the fungus.

Slow growth can mean soil temperature is too cold (tomatoes need 70 to 80 degrees to grow well), nutrients are lacking, or light is insufficient. Check soil temperature with a thermometer, and consider a heat mat under seed trays. Use potting soil, not garden soil, which compacts and lacks nutrients. If growth remains slow after addressing these factors, seedlings may need a diluted liquid fertilizer every 2 weeks.

Frequently Asked Questions

Can I grow tomatoes from store-bought tomatoes?

Yes, but only if the tomato is an heirloom or open-pollinated variety. Most supermarket tomatoes are hybrids, and seeds from hybrids produce plants that do not match the parent fruit — the tomatoes may be smaller, a different color, or taste different. Check the label or ask the farmer at a farmers market whether the variety is heirloom or open-pollinated before saving seeds.

How long does it take to grow a tomato plant from seed to fruit?

From seed to first ripe tomato usually takes 70 to 85 days, depending on the variety and growing conditions. This includes 6 to 8 weeks indoors as a seedling, 1 to 2 weeks hardening off, and 4 to 6 weeks in the garden before flowering and fruiting. Cuttings skip the seed stage and can produce fruit in 50 to 60 days.

Do I need rooting hormone to grow cuttings?

Rooting hormone is optional but helpful. It contains plant hormones that speed root formation and increase success rates, especially with woody or older stems. For soft, tender tomato stems, rooting hormone is less critical — many cuttings root fine in water or soil without it. It costs a few dollars and is worth having on hand if you plan to take cuttings regularly.

What temperature should I keep seedlings at?

Tomato seeds germinate best at 70 to 80 degrees Fahrenheit. Once seedlings emerge, they can tolerate slightly cooler temperatures — 65 to 75 degrees is fine. Temperatures below 60 degrees slow growth significantly. If your home is cool, a seedling heat mat placed under the seed tray will warm the soil without heating the whole room.

Can I save seeds from the same plant year after year?

Yes, if the plant is an heirloom or open-pollinated variety. Seeds from these plants will grow into plants that produce the same fruit, so you can save seeds each year and replant them. Hybrid plants will not breed true — seeds from a hybrid will produce plants with different traits. After a few generations of saving hybrid seeds, you will end up with unpredictable results.