The aubergine, botanically Solanum melongena, belongs like tomato and pepper to the nightshades and is a true sun worshipper. It comes from the tropics of Asia and needs, of all the fruiting vegetables in the garden, the most warmth and the longest season.
That is exactly what makes it a small challenge here: in the cool open ground it often just stands still. With the right spot, an early start and a little patience, though, you can harvest glossy, aromatic fruit even in Germany. This article shows you how.
The most heat-loving of the fruiting vegetables
The aubergine germinates only at around 25 degrees and grows only when it is really warm. Cool nights and draughts make it stand still and drop its flowers. That is why growing it in the greenhouse, the polytunnel or a large pot against a sunny south wall is almost always the safer choice than the open bed.
How to raise and harden off heat-hungry young plants correctly applies to the aubergine just as it does to its relative, the pepper and chilli. Both share the same demands almost to the degree.
The right harvest moment
With the aubergine people most often harvest too late, and that is punished with a bitter taste. The best indicator is the skin: as long as it is taut and shiny, the fruit is spot on. Once the skin turns dull and matt, the aubergine is overripe, the seeds grow hard and dark and the flavour tips into bitterness.
More than dark purple: the range of varieties
Whoever thinks of aubergine only as the fat, dark purple fruit from the supermarket misses a lot. The diversity in the garden is wide, and some types ripen earlier and therefore more reliably than the classic fat variety.
Which type suits you?
- Classic dark purple
The fat, club-shaped standard variety such as Aubergine 'Black Beauty'. Plenty of flesh, ideal for grilling and baking. Needs the longest and warmest season.
- Long Asian types
Slim and thin-skinned, often cropping earlier and more heavily. The flesh is more tender and milder, perfect for the pan and the wok.
- Striped and white
Pretty striped varieties such as Aubergine 'Listada de Gandia' or white, egg-shaped fruits. A visual highlight and often especially mild in flavour.
- Mini aubergines
Small-fruited varieties for pot and balcony. They ripen fast, crop heavily and are the best choice when the summer is short or space is tight.
How you grow aubergines
The sequence resembles that of the pepper, only a shade warmer and more patient.
Sow early
Sow from February to early March in seed compost. The season is long, an early start is decisive. How that succeeds is in Sowing on the windowsill.
Keep warm and bright
To germinate, the aubergine needs around 25 degrees. After that plenty of light counts, so the young plants stay sturdy and compact instead of growing leggy.
Harden off and plant out
Only after the Ice Saints in mid May does it go into the greenhouse or the pot. Accustom the plants slowly to the sun beforehand, see Hardening off young plants.
Support and pinch out
The plants grow heavy and topple easily, a stake gives support. Trained to two or three main stems and pinched out in moderation, they put their strength into fewer but larger fruits.
The aubergine forgives no cold. Give it the warmest spot, harvest while the skin still shines, and it rewards you richly.
The core rule for aubergines
Frequently asked questions
Why does my aubergine turn bitter?
Usually it was harvested overripe. As long as the skin shines, the fruit is mild. Once it turns dull and matt and the seeds darken, taste and texture grow bitter. Better to harvest a little early than too late.
Can I grow aubergines in the open ground?
In very warm spots and good summers yes, but the greenhouse or a pot against the warmest south wall is safer. Cool nights and wind make the plant stand still and drop its flowers, and then the harvest fails to come.
When do I have to sow aubergines?
Early, from February to early March on the warm windowsill. The culture is long and the plants grow slowly. Planting out happens only after the Ice Saints in mid May, when it is reliably warm.
Do I have to pinch out aubergines?
It helps but is no must. Trained to two or three main stems and pinched out in moderation, the plant forms fewer but larger and faster-ripening fruits. That pays off above all in cooler spots with a short season.
Why does my aubergine set no fruit?
Almost always it is too cool. Below about 15 degrees at night the aubergine drops its flowers and sets nothing. A warmer, more sheltered spot and even watering usually solve the problem.
