Growing tomatoes made simple for beginners: achieve a delicious harvest

Growing tomatoes: your guide to success

Sowing your tomato seeds

Sow seeds from February to April in clean plastic pots, using one or two seeds per pot. Lightly cover with sand or peat and label each variety. Use clean, unfertilized seed starting mix or garden peat. Keep the soil moist and cover with cloth until germination. You can also sow multiple tomato seeds in a shallow container.

Growing tomatoes from seeds

The optimal germination temperature is 22–25°C. Once sprouted, move seedlings to a bright area around 18°C, like a windowsill.

If natural light is insufficient, use plant lights. Adequate lighting of 14–16 hours daily ensures robust seedlings.

Begin fertilizing with a mild liquid fertilizer when seedlings have two pairs of leaves.

Transplanting and potting tomato seedlings

Once the roots reach the pot’s edges, transfer seedlings to larger pots. When they have two pairs of leaves, carefully transplant each seedling into its own pot. Be careful not to damage the roots. The lowest leaves should be at soil level and removed after planting. If the pot becomes too small, transplant again, burying the stem deeper if necessary to encourage root growth.

Plant tomatoes in their final location in a greenhouse or a warm outdoor spot only after frost risk has passed, ensuring temperatures remain above 10°C. Aim to plant the tomato when the first flower cluster opens.

Acclimatizing tomato seedlings

Gradually acclimate seedlings by exposing them to outdoor conditions for a few hours daily over several weeks, starting in the shade or under a protective cloth, then moving to sunlight.

Plant them outdoors or to a greenhouse when night temperatures remain above 8°C.

Tomato growing conditions and medium

An ideal growing medium is nutrient-rich garden patch, with ample phosphorus, compost, lime, and a pH of 6–7. Use nutrient-dense garden soil or grow bags.

Standard vine tomatoes thrive in pots of at least 10 liters or in well-fertilized beds.

Tomatoes need a sunny, warm, and wind-protected spot. Optimal daytime temperatures are 20–24°C and nighttime temperatures are 16–18°C. Cool temperatures slow growth, and frost protection or glass may be needed in cooler summers.

Planting your tomatoes

You can plant tomatoes up to the lowest leaves. For tender seedlings, remove the lower leaves and plant at an angle so deep that it stabilizes. Ensure adequate spacing: seedlings planted too densely are prone to fungal diseases. For vine tomatoes, 40–50 cm is suitable and for bush varieties, 60–80 cm.

Caring for and fertilizing tomatoes

Watering your tomato plants

During hot periods, especially when growth is most vigorous in July and August, tomatoes require ample water. Provide 3–4 liters per plant on hot days. However, tomatoes do not like wet soil but need even moisture. If the growing medium dries out in between, the fruits are prone to cracking. Only the surface soil can dry slightly between waterings. As the plants grow, remove the lower leaves of vine tomatoes.

Providing support for tomato plants

You can support your tomato seedlings with for example stakes or cages.You can easily make your own tomato support [in Finnish] or purchase one from a store.

Fertilizing your tomato plants

During the growing season, apply a fruit and berry plant or other low-nitrogen liquid fertilizer weekly. If the tops of the tomato plant are strongly green and curled, it may be a sign of over-fertilization, while pale leaves and stunted growth indicate nutrient deficiency.

Few flowers and withering may result from excessive nitrogen. Adjust the fertilization accordingly.

Encouraging tomato pollination

To aid pollination, gently tap the flower clusters daily. A paintbrush can also help, especially in greenhouses, to boost yields.

Temperature affects pollination success. Optimal pollen release occurs at 17–23°C. Below 15°C, pollen fails to germinate, and above 27°C, pollination is hindered.

Managing tomato suckers

Monitor tomato suckers [in Finnish] regularly. Suckers grow between the stem and leaf joint. Pinch them off, except for hanging basket and bush tomatoes.

Topping your tomato plants

Consider topping [in Finnish] tomatoes in late summer when they reach sufficient height or have enough clusters. Removing about a third of the plant’s leaves during topping allows more light for the fruits.

Ripening and cracking issues in tomatoes

Tomatoes typically ripen [in Finnish] a couple of months after planting.

Cracking in fall tomatoes often stems from reduced soil strength. Increase potassium-rich fertilizers as needed, following package instructions.

Sudden weather changes from sunny to cloudy can also cause cracking due to increased humidity, leading to excess liquid in fruits. Reduce watering significantly in late summer.

Early frosts typically end cultivation in September–October. When growth ceases, harvest green tomatoes to ripen indoors on a flat surface.

Tomatoes are unsuitable for crop rotation, thriving best when planted in the same location every year. Keep plants healthy with compost containing tomato debris. Add compost, horn shavings, bone meal, and composted chicken manure to the soil after harvest.

Tomato varieties: choosing for different mediums

Select a tomato variety based on the growing location. Different varieties suit pots, open fields, and greenhouses.

A warm wall or balcony also works well for tomatoes. Prioritize the warmest, brightest, and most sheltered spot for outdoor cultivation.

Label the variety name on the support to track growth specifics.

Varieties for open fields

Varieties for greenhouses

Varieties for balconies

Read more about different tomato varieties! [in Finnish]