Tomatoes grow from seed through a flowering stage, then develop fruit over 60 to 85 days depending on the variety

A tomato plant starts as a seed that germinates in warm soil, usually between 70 and 80 degrees Fahrenheit. Once the seed sprouts, a small seedling emerges with two seed leaves. Over the next 4 to 6 weeks indoors or in a protected space, the plant grows taller and develops true leaves — the ones that look like actual tomato leaves. When the seedling is 6 to 8 inches tall and the soil outside has warmed, you transplant it into a garden bed or container.

After transplanting, the plant enters a growth phase lasting 3 to 4 weeks. During this time, it develops a stronger root system and more branches. Once the plant is established, it begins to flower. The flowers are small and yellow, and they appear in clusters along the stem. Each flower that gets pollinated — by wind, insects, or your hand — will become a tomato fruit.

From the moment a flower is pollinated to the moment the fruit is ready to pick, 20 to 30 days pass. The fruit starts as a tiny green ball behind the flower, then swells as it fills with seeds, juice, and flesh. The color change from green to red (or yellow, orange, or purple, depending on variety) signals ripeness. This entire cycle — from seed to ripe fruit — takes roughly 70 to 85 days in warm conditions.

Key Takeaways

  • Tomato seeds germinate in 5 to 10 days in soil between 70 and 80 degrees Fahrenheit, and seedlings are ready to transplant outdoors when they reach 6 to 8 inches tall.
  • The plant spends 3 to 4 weeks establishing roots and branches after transplanting before it begins to flower.
  • Flowers must be pollinated to form fruit, and this happens naturally through wind and insects or can be done by hand.
  • From pollination to a ripe, harvestable tomato takes 20 to 30 days, with the color change from green to red marking readiness.

The seed and seedling stage

Tomato seeds need moisture, warmth, and air to germinate. If you start seeds indoors, plant them about a quarter-inch deep in seed-starting mix or potting soil. Keep the soil moist but not waterlogged, and maintain a temperature around 75 degrees Fahrenheit. A heat mat under the seed tray speeds germination to 5 to 10 days; without one, it may take 2 to 3 weeks.

Once the seedling breaks through the soil, it needs bright light — ideally 14 to 16 hours per day. A sunny windowsill works, but a grow light positioned a few inches above the seedlings produces sturdier plants. As the seedling grows its first true leaves (the ones that look like tomato leaves, not the smooth seed leaves), it develops the ability to photosynthesize and grow faster.

When the seedling has 2 to 3 sets of true leaves and is 6 to 8 inches tall, it is ready to transplant. This usually happens 4 to 6 weeks after germination. If you are moving it to a larger pot indoors before the garden, bury the stem deeper than it was in the seed tray — tomatoes will root along the buried stem and develop a stronger base.

Transplanting and the growth phase

Tomatoes need warm soil to thrive outdoors. Transplant seedlings into the garden or a large container once the soil temperature reaches at least 60 degrees Fahrenheit, and ideally after the last frost date in your area has passed. The plant will survive at 60 degrees but grows slowly; at 70 degrees or warmer, growth accelerates.

Space plants 24 to 36 inches apart, depending on the variety. Determinate varieties (bush types) need less space; indeterminate varieties (vining types) need more. Bury the stem deeper than it was in its pot — up to the first true leaves if the seedling is leggy. The buried stem will develop additional roots.

For 3 to 4 weeks after transplanting, the plant focuses on root and branch development. You may see little growth above ground during this time, but the root system is expanding. Once the plant is established — usually visible as faster leaf growth and thicker stems — it will begin to produce flower buds. This transition typically happens 4 to 6 weeks after transplanting, depending on temperature and sunlight.

Flowering and pollination

Tomato flowers appear in clusters called inflorescences. Each cluster can hold 5 to 10 flowers, and a healthy plant produces multiple clusters over the growing season. The flowers are small, yellow, and self-fertile, meaning they contain both male and female parts. However, the pollen must reach the stigil (female part) for fruit to set.

In nature, wind and insects handle pollination. Bees visit tomato flowers, and wind shakes the flowers as well. Indoors or in still conditions, pollination may not happen reliably. You can hand-pollinate by gently shaking the flower cluster when it is in bloom, or by using a small brush to move pollen from flower to flower. Hand-pollination takes only a few seconds per cluster and significantly increases fruit set.

A flower that is not pollinated will drop off the plant within a few days. A pollinated flower will retain its base (the ovary) and begin to swell into a fruit. You will see a tiny green ball forming where the flower was. This is the beginning of the tomato.

Fruit development and ripening

After pollination, the fruit grows rapidly for the first 10 to 15 days. The green tomato swells as it fills with seeds, juice, and flesh. During this phase, the plant needs consistent water and nutrients — a balanced fertilizer or one slightly higher in potassium supports fruit development. Irregular watering can cause problems like blossom-end rot (a dark, sunken spot on the bottom of the fruit) or fruit cracking.

Once the fruit reaches full size — typically 2 to 3 inches in diameter for most varieties — it enters the ripening phase. The color change from green to red (or the final color for your variety) is driven by temperature and light. Tomatoes ripen faster in warm conditions, around 75 to 85 degrees Fahrenheit. Below 68 degrees, ripening slows significantly. At temperatures above 85 to 90 degrees, the plant may stop ripening altogether and focus on survival.

The ripening phase lasts 10 to 15 days under ideal conditions. You can pick tomatoes at the "breaker stage" — when the first blush of color appears — and they will continue to ripen indoors. This is useful if frost is approaching or if you want to avoid splitting from heavy rain. A fully ripe tomato is soft to the touch and comes off the vine with a gentle twist.

Factors that affect growth speed

Temperature is the single biggest factor. Tomatoes grow fastest between 70 and 85 degrees Fahrenheit during the day and 60 to 70 degrees at night. Below 55 degrees, growth nearly stops. Above 90 degrees, the plant struggles, flowers may drop, and fruit may not set.

Sunlight matters too. Tomatoes need at least 6 to 8 hours of direct sun per day to grow well; 10 to 12 hours is better. In low light, plants grow tall and spindly, produce fewer flowers, and ripen fruit slowly. Water consistency also affects speed — a plant that alternates between dry and wet soil grows slower and produces lower-quality fruit than one watered regularly.

Soil nutrients support growth as well. A soil rich in organic matter and balanced in nitrogen, phosphorus, and potassium produces faster, healthier growth. Nitrogen promotes leafy growth; phosphorus and potassium support flowering and fruiting. A plant in poor soil will grow, but more slowly and with smaller fruit.

Indeterminate versus determinate varieties

Indeterminate tomatoes are vining plants that grow continuously throughout the season. They flower and fruit in waves, producing tomatoes from early summer until frost. These varieties take longer to reach first fruit — often 75 to 85 days — but they keep producing. Examples include 'Brandywine', 'Cherokee Purple', and 'Sungold'.

Determinate tomatoes are bush types that grow to a set size, then flower all at once or in a short window. They produce most of their fruit within 2 to 3 weeks, then slow down or stop. These varieties reach first fruit faster — often 60 to 70 days — and are popular for canning because the harvest is concentrated. Examples include 'Roma', 'San Marzano', and 'Mountain Magic'.

The choice between the two depends on your goals. If you want tomatoes throughout the summer, choose indeterminate. If you want a large harvest at once for preserving, or if you have a short growing season, choose determinate.

Common problems during growth

Blossom-end rot appears as a dark, sunken spot on the bottom of the fruit. It is caused by calcium deficiency, usually triggered by irregular watering. Keep soil consistently moist, not waterlogged, and mulch around the plant to regulate moisture.

Flower drop happens when flowers fall off without setting fruit. Causes include temperature stress (below 55 or above 90 degrees), inconsistent watering, or too much nitrogen fertilizer. Adjust conditions and wait for the plant to produce new flowers.

Slow ripening in late summer is normal as temperatures cool and daylight shortens. You can pick fruit at the breaker stage and ripen it indoors, or prune some foliage to allow more light to reach the fruit.

Splitting or cracking occurs when fruit absorbs water too quickly after a dry spell. Consistent watering and mulch prevent this. Varieties differ in crack resistance; 'Sungold' and 'Black Cherry' are prone to splitting, while 'Roma' and 'San Marzano' are more resistant.

Frequently Asked Questions

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

From seed to ripe fruit takes 70 to 85 days under warm conditions. This includes 5 to 10 days for germination, 4 to 6 weeks for seedling growth, 3 to 4 weeks for establishment after transplanting, 3 to 4 weeks until flowering, and 20 to 30 days from pollination to ripeness. Cold soil or air slows every stage.

Can I pick a green tomato and ripen it indoors?

Yes. Pick tomatoes at the breaker stage — when the first hint of color appears — and place them on a windowsill or in a paper bag at room temperature. They will ripen in 5 to 10 days. Fully green tomatoes take longer and may not develop full flavor, but they will ripen if the fruit is mature enough.

Why are my flowers dropping without making fruit?

Flowers drop when the plant is stressed by temperature (below 55 or above 90 degrees), inconsistent watering, or too much nitrogen. Check soil moisture, may support the plant gets 6 to 8 hours of sun, and avoid over-fertilizing. New flowers will appear once conditions improve.

Do I need to hand-pollinate my tomatoes?

Outdoors, wind and insects usually pollinate tomatoes, so hand-pollination is not necessary. Indoors or in a greenhouse with no air movement or insects, gently shaking the flower clusters or using a small brush to move pollen between flowers increases fruit set and yield.

What temperature is best for growing tomatoes?

Tomatoes grow fastest between 70 and 85 degrees Fahrenheit during the day and 60 to 70 degrees at night. Below 55 degrees, growth stops. Above 90 degrees, the plant struggles and may drop flowers. Consistent warmth produces the fastest growth and best fruit.