Stages of Tomato Plant Growth

Understanding the various stages of growth in a tomato plant can significantly enhance your tomato-growing success. Each stage has its unique characteristics and care needs.

This guide will take you through the journey of a tomato plant, from seed to ripe fruit, highlighting the essential care at each stage. I have included the best time of year for each stage and the number of days each stage should take; helpful if you have small children telling you “nothing is happening”.

StageApproximate Duration
Germination5-14 days
Seedling Stage4-6 weeks
Transplanting1 day (Process itself)
Flowering2-3 weeks after transplanting
Fruit Set and Ripening2-3 months
HarvestingVaries (Until first frost)

Stage 1: Germination

Tomato growth begins with seed germination. This process typically starts once the seed is sown in warm, moist compost or a specialised seed-starting mix. In the UK, this is usually done indoors around late February to early March. After 5-14 days, you’ll see the first sign of life as the seedling breaks through the soil surface.

The emerging plant has two embryonic leaves known as cotyledons, which provide the seedling with initial nutrients.

startaing off my tomato seeds

During this stage, seedlings need warmth more than light, so keep them in a warm spot or use a heat mat to maintain an optimal temperature of around 18-21°C.   I use heated propagators to keep the soil at a consistent temperature; sometimes, window sills can become cold and draft, especially if you live in an old house like mine.

Stage 2: Seedling Stage

Once the true leaves that look like tomato leaves start appearing, the plant enters the seedling stage. This stage is characterised by rapid foliage growth. Seedlings require plenty of light to prevent them from becoming ‘leggy’ and weak. A sunny windowsill or under grow lights will suffice if you’re growing them indoors.

This is also the stage where you might need to ‘prick out’ or ‘pot on’ your seedlings, transferring them to larger pots if they start outgrowing their initial containers. Continue to keep the compost moist but avoid waterlogging.

Stage 3: Transplanting

Once the risk of frost has passed and the plants are around 15-30cm tall – usually from mid to late spring in the UK – it’s time to transplant your tomatoes to their final growing location. This could be a greenhouse, outdoor beds, or containers, depending on the tomato variety and your preference.

Seedlings being moved from the propagation tray to larger pots.


Ensure the plants are well ‘hardened off’ before transplanting. This involves gradually acclimatising them to outdoor conditions over a week or two. When planting, bury the stems up to the first set of leaves. This encourages the growth of additional roots along the buried stem, leading to stronger plants.

Stage 4: Flowering

After the transplanting stage and as the weather warms, tomato plants enter the flowering stage. The plant’s energy focuses on creating blossoms, which will become the fruit.

To encourage fruit set, you might want to provide a tomato-specific feed, which is high in potassium. Keep the plants consistently watered, as erratic watering can lead to issues like blossom end rot or fruit cracking.

Stage 5: Fruit Set and Ripening

After successful pollination, the flowers will develop into green tomatoes, marking the fruiting stage. The small fruits will continue to grow and eventually begin to change colour, indicating the ripening process.

During this stage, continue with regular feeding and watering. In some cases, you might need to support the plants if the weight of the fruits becomes too heavy for the stems to support.

Stage 6: Harvesting

The final stage is the most rewarding – harvesting. For most varieties, the fruit is ready when it achieves its full colour, whether red, yellow, orange or even purple. Tomatoes can be harvested as soon as they start to show colour and are allowed to ripen fully indoors if needed.

After harvesting, the plants will continue to produce until the first frost of autumn. Then, the cycle can start again next spring!

Understanding these stages of tomato growth and their specific care needs can greatly improve your tomato-growing success. From germination to harvest, each phase is part of the fascinating journey of growing tomatoes, bringing the joy and satisfaction that comes with cultivating your own delicious fruit.