How to grow aubergines
Learning to grow your own aubergines. Tips and helpful information.
The aubergine is a vegetable that belongs to the solanaceous or potato family, and which is known scientifically as Solanum melongena.
It is an herbaceous plant although the stems, with their lignified woody tissue tend to make it resemble a small tree or bush. It is cultivated as an annual.
The aubergine plant possesses a very strong deep root system.
The stems are strong, hairy and thorny with a determined growth rate when referring to creeping shoots or an indefinite growth rate when talking about straight, erect stems.
The main stem includes short internodes which fork out into secondary stems, which then divide at the leaf axils.
The leaves are positioned alternately along the stem. They have a long stalk and are large, complete and oval in shape with thorny nerves.
The underneath part of the leaves are covered with a greyish down.
The flowers tend to droop and can appear either by themselves or in clusters of 3 to 5 flowers.
They possess between 5 and 7 green sepals and the same number of elongated violet petals.
The stamens have highly developed anthers which are yellow in colour and are situated under the stigma, which makes direct fertilization difficult.
The fruit is an egg-shaped or bulbous berry which is black, purple, white or white-tinged purple or green with small yellow seeds.
The aubergine requires a warm dry climate which is why it is considered to be one of the most demanding crops with regard to heat.
It is a plant that thrives in high temperatures as long as the relative humidity is at the right level. It will tolerate temperatures as high as 40-45ºC, although the average temperature must be set between 23-25ºC.
With regard to optimum relative humidity, this will vary between 50% and 65%. A very high relative humidity will encourage the development of air born diseases, and this in turn, will make fertilization difficult.
The aubergine is a plant that needs a lot of sunlight and it will require between 10 and 12 hours daily.
With respect to soil requirements, the aubergine is not particularly demanding, nevertheless, the best soil for growing this crop is deep loamy soil.
Choked roots may be the result if aubergines are cultivated in siliceous soils.
Optimum pH levels for soil vary between pH 6 and pH 7 although in sandy soils this crop may be grown with pH levels set between pH 7 and pH 8,5.
The use of acidic soil will cause problems with regard to both the growth and production of this crop.
When considering soil salinity and the water used to irrigate, it must be said that the aubergine is less resistant than the tomato and more resistant than the pepper.
The planting of aubergine plants in greenhouses is carried out with seedlings taken from seedbeds.
Transplanting into permanent soil takes place 45−50 days after the seeds are sown in seedbeds, and once the plant has 4−6 well established leaves and has grown to a height of between 10−12 cm.
In order for transplanting to take place, holes are made in the soil and once the root ball is placed into the hole it is covered and watered so the plant takes a firm foothold with regard to the root taking process.
The setting for planting is established depending upon; the requirements of the variety of aubergine being cultivated, the system of cultivation being employed, the crop cycle and the number of stems to be left for the proper formation of plant shoots.
Once the plant has taken root and up to the beginning of fruit formation, the irrigation points should be situated as far away as possible. This is so that the root system might be encouraged to permeate deeply into the soil, therefore ensuring that vegetative growth does not take place too quickly. If the contrary were to occur, the ensuing lush foliage may well cause difficulties with relation to flowering and the fertilization of the flowers.
At approximately the 40−50 day stage after transplanting, pruning for the proper formation of plant shoots takes place, and due to this, the number of shoots that the plant will develop is deliberately limited to 2, 3, or 4.
Staking and tying the plants will maintain them in an upright position; it will also improve general aeration of the plants and will make it easier to take advantage of sunlight and to undertake all of the care necessary with relation to crop production.
De−leafing consists in removing those leaves which can be found situated under the “cross”, such as senescent leaves. In this way, both aeration and an improvement in fruit colour will be facilitated.
It is also necessary to carry out a thinning out of the fruit, this will ensure the elimination of any fruit which may have been damaged or deformed due to plagues or disease.
Normally, the first inflorescents will appear at the “cross” of the plant, approximately 20−30 days after transplanting has taken place.
In order to improve the pollenization of the flowers, beehives of Bombus Terrestris are placed inside the greenhouse.
After the fertilization of the flower has taken place, the ovary will begin to develop and will turn into a fruit. From this moment onwards, the water requirements of the plant will increase. Therefore, watering must be adjusted in accordance to the specific needs of the plant, and depending upon its rate of evapotranspiration.
With regard to nutrition, it is important to take care with regard to the amount of nitrogen fertilizer used, in order to prevent excessive vegetative growth.
Whitefly and thrips are among the main plagues that are found to adversely affect the aubergine plant.
In order to biologically control these plagues the release of auxiliary fauna is undertaken, the most commonly practised method being the use of Amblyseius swirksii and Nestidiocris tenuis.
Depending upon both crop and temperature, the growth period from flowering to harvest will range from 10 to 40 days.
Fruit picking should be carried out while the fruit has still not reached physiological maturity as the presence of seeds within the fruit will make their taste bitter.
The fruit should be cut in the morning, and if possible, they should be exempt from any humidity or wetness. Pruning shears should be used in order to avoid any tearing of the fruit and so that at least one centimetre of the stalk remains.
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