General
Aubergine is a heat-loving member of the nightshade family grown as an annual in cool climates. It needs long, warm summers or a greenhouse/tunnel in most of Sweden. Compact cultivars suit pots; larger types need staking. Consistent warmth, high light and steady watering are key to preventing blossom drop and producing glossy, firm fruits.
Light
Full sun; 8–10 hours of direct light daily. Warm, sheltered exposure.
Soil type
Deep, fertile, well-drained loam enriched with mature compost; high organic matter. Use large containers (15–20 L) with airy peat-free mix if growing in pots.
Water requirement
Even moisture; never waterlogged. Water deeply 2–4 times per week depending on weather. Mulch to reduce evaporation.
Nutrient requirement
Heavy feeder. Moderate nitrogen early; higher potassium and calcium from flowering to harvest. Use balanced organic fertilizer at transplant, then K-rich feeds.
Precultivation
Sow indoors 8–10 weeks before the last frost. Optimal germination temperature is 24–28°C; use a heat mat until emergence. Sow 0.5–1 cm deep in small modules; prick out once true leaves appear. Provide strong light (grow lights 14–16 h/day) and keep temperatures 18–22°C after germination to avoid leggy plants. Pot up progressively to 9–12 cm pots; do not let roots get pot-bound. Harden off 7–10 days before planting.
Planting
Plant when nights are reliably above 10–12°C and days above 18–20°C (air temp ≥15°C). Spacing: 45–60 cm between plants and 60–75 cm between rows, or one plant per 15–20 L container. Incorporate well-rotted compost and a balanced organic fertilizer at planting. In greenhouses, maintain good airflow and avoid cold drafts. Use dark mulch or black fabric to warm soil; consider cloches early in the season.
Pruning
Stake or cage most cultivars. Remove the first flower on small plants to encourage vegetative growth. For larger types, prune to 2–3 main stems by removing weak side shoots below the first fork; thin excess suckers for better airflow. Pinch growing tips in late summer to direct energy into ripening existing fruit.
Maintenance
Keep soil evenly moist; avoid swings that cause blossom end rot. Mulch with straw/leaf mold. Feed every 10–14 days from first flowers with a potassium-rich organic feed (e.g., tomato fertilizer or comfrey tea) plus a source of calcium if needed. Maintain daytime 22–28°C, nights 16–20°C; shade lightly above 30–32°C and ensure ventilation. Gently tap flowers at midday to aid pollination.
Harvest
Pick when fruits are glossy and firm; the skin should spring back after a gentle press and seeds are still pale/soft. Color should be full (purple types deep purple; white/green types before any yellowing) and the calyx bright green; dull skin means overripe. Cut with secateurs leaving a short stem—beware spines on the calyx. Frequent picking speeds further set; in cool climates, stop new flowers and pinch tips 3–4 weeks before season end and harvest all usable fruit ahead of the first frost. Store short-term at 10–12°C (not in a cold fridge).
Common issues
Blossom drop: usually cold nights, heat >32°C, or drought; stabilize temperature and moisture. Blossom end rot: calcium imbalance from uneven watering—mulch and steady moisture. Aphids/whitefly/red spider mite: encourage beneficials, use insect netting, wash with soap solution if needed. Flea beetles outdoors: use row cover and sticky traps. Verticillium/wilt: practice strict rotation, avoid planting after nightshades, use clean pots and media.
Rotation schedule
Rotate away from nightshades for 3–4 years. Follow heavy feeders with legumes or green manures. In containers, replace or sterilize growing media each year.
Pollination
Self-fertile flowers; pollination improved by bumblebees and gentle vibration/shaking.
Companion plants
Basil, marigold (Tagetes), nasturtium, oregano, thyme, chives, bush beans, peas, calendula. Flowers that attract bumblebees are beneficial.
Incompatible plants
Fennel, potatoes; avoid planting next to or after other nightshades (tomato, pepper, potato) due to shared pests and diseases.
