Aubergines or eggplants as we also call them were thought to be exotic but are now becoming popular vegetables to grow at home in the greenhouse, mainly thanks to new cultivars that are more suited to the British climate. Generally, they are frost-sensitive and will really enjoy a warm climate.
Aubergines belong to the same family as tomatoes, potatoes and peppers as they are members of the Solanaceae family. Unlike aubergines, these were all found in the Americas whereas the eggplant is Asian if not an Indian plant because of its place in their cuisine.
The eggplant is fantastic and iconic in Mediterranean dishes. Moussaka from Greece is probably THE iconic eggplant dish. In India it is known as brinjal. Commercially in Asia it is a highly productive and important food crop. These plant probably began in cultivation in India but the Chinese started growing them 2,500 years before they were taken along the silk road and grown both in the Middle East and Africa. In Europe, the fruits were grown when trading with merchants from the Middle East. The French know the plant as ‘aubergene‘ because the Spanish call them’ berenjena‘ which is derived from Moorish Arabic. The Italians call aubergines ‘melazana‘ or mad apples which again is derived from Arabic and refers to a particular type of aubergine which they were especially fond of. The name became ‘melongene‘ and led to their scientific name Solanum melongena.
Aubergines produce extremely versatile and delicious fruit although these are all used in savoury dishes. There are many types available where deep-purple or a black colour is the most common but other types include white, pink, orange, yellow, multi-coloured, freckles and green and they also appear in different sizes and shapes. Shapes include round or spherical, long and thin. Sunshine and warm growing conditions are the keys to success as they grow similarly to tomatoes and peppers which they are related to. The greenhouse really is the best place for them unless you live in a frost free, relatively warm part of the UK.
Modern cultivars are F1 hybrids. There are also a number of wide ranges of older open pollinated types where they are bred in East and South Asia. They make great ornamental plants for the warm conservatory and sunny patios in more northern climates. Try them in containers.
Varieties Of Aubergines
‘Black Pearl‘ F1 hybrid. Deep coloured, high-yielding type, suitable for greenhouse growing.
‘Bonica’AGM F1 hybrid: Ideal for an unheated glasshouse, early cropping with top-quality, good-sized, attractive, glossy black fruits. More tolerant of a cooler season than some.
‘Clara‘ AGM F1 Hybrid. Heavy cropping with large white fruits. Not suitable for outdoor cultivation.
‘Emerald Isle‘ F1 hybrid. Numerous small green fruits.
‘Fairy Tale‘ AGM. Compact plants bearing many elongated small lavender-purple fruits. Well suited to container cultivation.
‘Galine‘ AGM F1 hybrid. Compact, producing small purple fruits, suitable for containers.
‘Giotto‘ F1 hybrid: Moneymaker type with tolerance of verticillium root disease. Round fruits. Good for outdoor cultivation because of its verticillium resistance.
‘Kaberi‘ AGM F1 hybrid. Compact fruits, suitable for container and patio cultivation.
‘Ophelia’ – common type and quite hardy.
‘Moneymaker‘ F1 hybrid. Large slightly elongated purple fruits. Nowadays being superseded by modern cultivars but is worth it for cooler environments.
‘Pintung Long’: The slender lavender/purple fruits, which are tender and full of flavour, grow to 30cm long.
‘Rosa di Bianca‘ (Organic) F1 hybrid. Attractive, spherical fruits with a creamy, delicate consistency.
‘Thai Green Pea’: A tall plant, covered with masses of tiny green fruit with a strong aubergine flavour. Ideal in Thai recipes.
‘Red Egg’ a fat red fruiting type
‘Rossa Bianca’: A gourmet variety with white, rose-tinted fruit and a mild, creamy taste.
‘Violette di Firenze’: Unusual dark mauve fruits make this an attractive plant for the potager. It needs warmth to ripen fully and is similar but a longer version.
Scatter the seeds thinly on top of moist compost – Levingtons No. 1 is ideal. Most seeds germinate so you only need to sow two more seeds than you need in case of losses from wilt. The seed must be sown early in the year; February is the earliest time because of cold so a heated plant propagator is invaluable. A temperature of 21 Centigrade is ideal for a propagator. Alternatively, germinate seedlings in the airing cupboard or warm but dark room. Cover the seeds trays when in the dark with a sheet of polythene but let air circulate.
Cover seeds with a fine layer of vermiculite, water and label – this is important to help you identify them when sowing several varieties. Light is important but not necessary in the first instance. Only bring into a warm, light once these very small seedlings have germinated.
Although aubergines can be grown outside, they rarely do well except in mild areas or during very good summers. As a result they are better grown in a greenhouse or growing frame.
Plant the seedlings, as soon as they can be handled. Grow in 9cm (3½in) pots initially or cells from February onwards. Use a good general purpose compost, ideally peat-free and in a bright, warm place. Although a heated greenhouse (20-27 Centigrade) is great, good results are also possible using sunny windowsills.
Feed plants every week from four weeks after potting, using a balanced liquid fertilizer.
If planting out is not possible until later, repot these pots when the roots have fully filled their containers into 12-15cm sizes. When the next pot is filled with roots, transfer plants again to 23cm (9in) pots of compost in April in a heated greenhouse, or early May if unheated, or the end of May or early June if growing outdoors. Plants can be put into greenhouse growing bags or larger pots even. A grow bag will hold three plants. We prefer black pots filled with growing bag compost and placed in a bag. Black pots offer the warm root conditions that aubergines love as they harvest the sun’s warmth. Allow 45cm between plants and 75cm between rows.
Keep between 20 and 27 Centigrade. Do not allow temperatures to fall below 12 Centigrade.
Aubergines can also be grown in the open ground, in warm parts of Britain, spacing 60cm (2ft) apart, and ideally covered with cloches or fleece. The keys to success are sunshine and warm growing conditions. Warm the soil with polythene or cloches two weeks before planting once there is no danger of frost and cover young plants in cloches or frames for a further two weeks until acclimatised. Grow them in a sheltered, sunny position, ideally against a warm, sheltered wall. Start this type of growing in early June. A modest crop should be possible.
It is feasible to obtain ready grown young plants as offered by mail-order or through garden centres. They are offered from mid-spring at reasonable prices. Such plants need a long growing season so such plants are invaluable when temperatures are too low for sowing and a heated greenhouse is not available. Interesting results are obtained with grafted plants where they are grown on tomato rootstock. The rootstock offers exceptional vigour and also resists widespread verticillium fungal wilt disease.
Flowers are self-fertile but a lack of fruit set is a major problem with these plants. It all depends on the growing conditions and if they can be improved then do so.
Plants should be staked and tied against stout canes as they grow because the fruits will be weighty and hopefully numerous. When plants are 25-30cm (10-12in.) high, the tip is removed from the main stem to encourage further spreading and fruiting. The first flowers appear when the plants are quite small. You should see these flowers in mid-Summer. When this happens feed weekly with a high potash liquid feed such as one used for tomatoes.
Water regularly and feed with a high potassium liquid fertiliser every two weeks once the first fruit has set. Mist the foliage regularly, at least twice daily with tepid water as they like high humidity, it reduces red spider mite and helps fruit to set.
Once five or six fruits are set, all flowers should be removed. However, cultivars producing small or round fruit can be allowed to produce many more.
Most plants produce up to five fruits but this depends on the weather and the variety. Each fruit is cut from August onwards when they’ve grown about 15cm (6in.) long and the skin surface is still shiny. Cropping can continue well into the winter.
Harvest fruits as soon as they begin to develop their colour. If the fruits are white, pick when firm and glossy. Harvesting stimulates further fruits to form until the winter weather arrives.
Problems Growing Aubergines
Aubergines are generally pest and disease free but you can encounter issues with greenfly and aphids. Use biological controls is necessary. Another problem is red spider mite. It prevails when plants are under stress from dry conditions. Raise the humidity and try and bring in predators to be truly effective. Bring predators in before these mites become too numerous. Another issue caused by poor watering regimes is blossom end rot which is irreversible and leads to fruit loss. .
Whitefly is an occasional problem. Again predator control will work effectively. If the infestation is too large, some preliminary treatment is needed before any biological control can be used effectively. Insecticides based on vegetable oils and fatty acids or soaps. The pretreatment has little impact on the beneficial insects or the later biological controls
The leaves and fruits are eaten to produce holes. These are produced by tomato moth caterpillars, snails, slugs etc. Best picked off and squashed using a torchlight after dark.
We have mentioned verticillium fungal wilt a few times. It is a common fungus found in soils where it persists for long periods. It invades water conducting vessels called the phloem which leads to leaves or various parts of leaves. These wilt when the fungus invades. The infected plants often survive long enough to produce fruit but the crop is significantly reduced. The best and probably only recipe is to grow the plants in fresh soil-potting media. Grafted types are usually unaffected or at worst mildly damaged.
Aubergines don’t store very long so they are best kept in the refrigerator. Most can be sliced and cooked for freezing where they are used as a base in sauces for pastas, lasagne and soups. Roasting and storage in olive oil to serve as a starter is also a delight.
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