Why Grow Tomatoes from Seed?
Tomatoes are one of the most rewarding crops a home gardener can grow. Starting from seed — rather than buying transplants — gives you access to hundreds of varieties, saves money, and lets you control every stage of growth. This guide walks you through the entire process from seed to ripe tomato.
What You'll Need
- Tomato seeds (choose a variety suited to your climate)
- Seed-starting mix (not regular garden soil)
- Small pots or seed trays with drainage holes
- Grow lights or a sunny south-facing windowsill
- Watering can with a gentle rose head
- Liquid fertilizer (balanced NPK for seedlings)
- Stakes or cages for support
Step 1: Starting Seeds Indoors
Start tomato seeds 6–8 weeks before your last expected frost date. Fill seed trays with moist seed-starting mix and plant seeds about 6mm (¼ inch) deep. Cover lightly with mix, mist with water, and cover with a plastic dome or cling wrap to retain humidity.
Place trays somewhere warm — tomato seeds germinate best at 21–27°C (70–80°F). Seeds typically sprout within 5–10 days.
Step 2: Providing Light
Once seedlings emerge, remove the cover immediately and move them to bright light. Seedlings need 14–16 hours of light per day. A grow light positioned 5–10cm above the seedlings works best. Without sufficient light, seedlings become "leggy" — tall and spindly — and won't develop into strong plants.
Step 3: Transplanting to Larger Pots
When seedlings develop their first true leaves (the second set of leaves), transplant them into individual 10cm (4-inch) pots. Bury the stem deeply — tomatoes can grow roots all along their buried stem, creating a stronger root system.
Step 4: Hardening Off
Before moving plants outdoors permanently, they need to be "hardened off" — gradually acclimatized to outdoor conditions. Over 7–10 days, place plants outside for increasing periods each day, starting in a sheltered, shady spot and gradually introducing more sun and wind.
Step 5: Planting in the Garden
Plant tomatoes outdoors after all frost risk has passed and soil temperature is at least 16°C (60°F). Space plants 45–90cm apart depending on variety. Dig a deep hole and bury the stem up to the lowest leaves. Add compost to the planting hole for a nutrient boost.
Step 6: Supporting and Pruning
Install stakes or cages at planting time to avoid disturbing roots later. For indeterminate (vining) varieties, remove "suckers" — the shoots that grow in the crotch between the stem and a branch — to keep plants focused on fruit production. Determinate (bush) varieties need little pruning.
Step 7: Watering and Feeding
Water deeply and consistently — about 2.5–5cm (1–2 inches) per week. Inconsistent watering causes blossom end rot and fruit cracking. Once flowers appear, switch from a balanced fertilizer to a low-nitrogen, high-phosphorus formula to encourage fruiting over leafy growth.
Step 8: Harvesting
Most tomato varieties are ready to harvest 60–85 days after transplanting. Harvest when fruits are fully colored and slightly soft to the touch. Tomatoes actually continue to ripen indoors at room temperature — you don't need to wait for them to be perfect on the vine.
Growing Timeline at a Glance
- Weeks 1–2: Seed germination indoors
- Weeks 3–6: Seedling growth under lights
- Week 7: Transplant to larger pots
- Weeks 8–9: Hardening off outdoors
- Week 10: Plant in garden
- Weeks 11–18: Growth, flowering, fruit set
- Weeks 18–24: Harvest season begins