How Do I Start Aubergines (Eggplants) Indoors from Seed?

Aubergines are among the most heat-demanding vegetables to grow in a temperate climate. Outside the Mediterranean and warm US zones, they essentially require a greenhouse or polytunnel to produce reliably. But starting them correctly from seed gives you the best possible chance — and success with aubergines from seed is deeply satisfying.

When to Sow Aubergines

Sow aubergines 10–12 weeks before your last frost date — typically late January to mid-February in the UK and most of the northern US. Their long growing season and slow early growth mean an early start is non-negotiable if you want to see fruits before autumn. In cooler climates, aubergines usually produce better when kept under glass all season rather than planted out.

Germination Requirements

Aubergines need 24–27 °C (75–81 °F) at compost level for reliable germination. Below 20 °C germination is very slow; below 15 °C it largely fails. A thermostatically controlled heated propagator is strongly recommended. Sow seeds 5–6 mm deep in individual pots or cells, cover, and place in the propagator. Expect germination in 10–21 days at the right temperature. Seeds from the previous year may be slower — sow two or three per cell and thin to the strongest.

After Germination: Light and Warmth

Aubergine seedlings are very sensitive to cold. Keep them at 18–20 °C during the day and never below 15 °C at night — cold nights cause purple discolouration of leaves and stunted growth that is hard to reverse. Give them 14–16 hours of light daily; grow lights are particularly valuable for aubergines started in January and February when natural light is at its lowest.

Potting On

Prick out or thin to one plant per pot at the first true leaf stage. Move into 9 cm pots, then 13 cm pots as growth demands. Aubergines are bush plants that do not need staking while small, but they develop into substantial plants (60–90 cm in a pot) by planting-out time. Use a rich potting compost from the first pot-on stage and feed with dilute balanced fertiliser weekly from the third true leaf stage.

Growing On: Greenhouse vs. Outdoors

In the UK and similar climates, aubergines are best kept in a greenhouse or polytunnel all season — they simply do not get enough sun and warmth outdoors to fruit reliably. In warm parts of the US (zones 7 and above) they can be planted out after all frost risk passes. Harden off carefully over two full weeks before any outdoor planting, as aubergine foliage scorches easily in direct outdoor sun.