In this article, we will discuss how to cultivate organic eggplants while defending the plant against pest attacks. Eggplant is one of the quintessential summer vegetables, and its cultivation has some peculiarities. This is especially true for organic pest control since this cultivar is a favorite target of harmful insects in the garden. So, if we want to grow eggplants organically, we need to pay attention to various aspects that are essential for a healthy crop.
These are small but crucial details, and in this article, we will examine them in detail.
Eggplant, origin, and spread
Eggplant, known as Solanum Melongena in Latin, is a vegetable that belongs to the Solanaceae family, just like tomatoes. Therefore, the rules of crop rotation apply to it as well.
The plant is native to South Asia, probably India, where it has been cultivated since ancient times. It arrived in the Mediterranean with the Arabs in the 15th century, first in Spain and then in Italy, particularly in Sicily, where its cultivation is still one of the most widespread gardening practices.
The name “eggplant” comes from the Arabic word bandigian, which transformed into “melangiana” in Italian and then “melanzana”, interpreted in popular tradition as “unhealthy apple”. This name comes from the fact that the vegetable cannot be eaten raw due to the presence of solanine, a toxic substance for our body.
Characteristics of eggplant plants
Eggplant is one of the hardiest and most resistant vegetables from many points of view. Observing a grown plant, you can see that it resembles a small bush. It has an erect stem with many branches, easily reaching 70 cm or more in height. The leaves have small spines at the center, which can be quite annoying, and are covered with a thin down. Like tomatoes, the eggplant shoots, which later become branches, emerge at the intersection between the leaf and the stem. The flowers, small and spiny, usually have a purple color.
For eggplants to grow, they require pollination, and the plant is self-pollinating, meaning its flowers are hermaphroditic. The plant can, therefore, have self-pollination or cross-pollination, which occurs through insects. This adaptation gives eggplant cultivation a certain resilience and high productivity, even in the absence of pollinating insects.
Varieties and Nutritional Aspects of Eggplants
There are countless types of eggplants, varying in color, shape, taste, and, of course, culinary uses. We have black, purple, white, or red eggplants. They come in round, oval, elongated, or mushroom-shaped varieties. Some are ideal for roasting, others for stuffing, and still, others are used for preserving, and so on.
From a nutritional standpoint, eggplants are ideal for low-calorie diets, as they provide only 18 kcal per 100 grams. They contain a lot of water, are rich in minerals such as potassium, and offer an excellent source of vitamins A and C. To fully benefit from their dietary advantages, careful attention should be paid to their preparation in the kitchen. One of their characteristics is the very spongy flesh, which can hold seasoning, such as oil, very well, sometimes resulting in a dish that is far from low in calories. Therefore, if you want to use them for a diet, grilling or boiling them would be the ideal cooking methods.
A curious aspect related to eggplant cultivation is its contribution to technological development in the field of solar energy. The anthocyanin pigment present in this vegetable is, in fact, an essential element for the composition of third-generation photovoltaic cells.
How to Grow Organic Eggplants
To grow healthy and vigorous eggplants, it is essential to avoid frost and temperatures below 10°C (50°F). Eggplants prefer a mild climate but can withstand heat well.
Sowing and Transplanting Period
When it comes to choosing whether to grow eggplants from seeds or seedlings, similar considerations apply as we discussed in how to grow organic tomatoes. Eggplants, being part of the Solanaceae family, require a considerable amount of time to develop from seeds into seedlings. We’re talking about at least 45 days, so it’s essential to calculate your timing and the transplanting period. It is recommended to use a seedbed for seedling formation and avoid sowing directly in the field. This prevents the seeds from being overwhelmed by weeds. Seedbeds offer more control and protection in case of adverse weather conditions.
Also, don’t forget to choose organic seeds or seedlings from certified producers or through seed exchange.
Finally, the ideal transplanting period is from March to May for greenhouse cultivation, and from April to the end of June for open-field cultivation.
Growing eggplants requires special care, especially regarding adequate soil preparation, which can be done manually or mechanically. Eggplant plants have strong and vigorous roots that penetrate deep into the ground, resembling thick fibrous roots. The soil should be worked deeply to allow the roots to develop optimally. Hard clods should be removed as they can negatively impact the well-being and growth of the plant. If possible, using a tractor and ripper is recommended.
Similarly, pre-seeding fertilization should be generous. To grow vigorously, eggplant cultivation requires a significant amount of organic matter, particularly nitrogen, which is essential for vegetative growth.
During the winter months, in the areas of the soil designated for eggplant cultivation, apply ample amounts of cow or horse manure.
If you cannot find manure near your land, you can purchase pelletized manure commercially.
A crucial aspect is crop rotation. Eggplants, being part of the nightshade family, significantly deplete the soil. It is necessary to follow them with lighter crops both before and after cultivation.
Excessive soil exploitation can lead to problems and diseases in subsequent crops, and it may even encourage the presence of nematodes, actual parasites that thrive in tired soils. Intensive eggplant cultivation can indeed exhaust the soil.
To address this, avoid planting eggplants in the same area where tomatoes grew the previous year. Additionally, during the autumn and winter months immediately after growing eggplants, avoid planting heavy crops like cruciferous vegetables (cabbage, savoy cabbage etc) that further exhaust the soil. Instead, opt for lighter crops like lettuce (romaine and leaf lettuce) or consider using green manure with leguminous plants to naturally replenish the soil with nutrients.
Irrigation and Transplanting Distances
As you can imagine, growing eggplants requires a substantial water supply due to their deep roots and dense vegetation.
To avoid water wastage and dangerous waterlogging, we strongly recommend using drip irrigation whenever possible, using hoses with drippers for even water distribution.
Regarding proper irrigation spacing, eggplant plants need plenty of space to grow adequately. We recommend a distance of 60 cm (about 24 inches) between each plant and one meter (about 40 inches) between rows.
A fundamental practice for successful organic eggplant cultivation is mulching. Eggplants have a long life cycle and can last from May to late October if well-tended and under the right conditions. Performing regular manual cleaning operations is impractical, so mulching becomes essential.
For eggplants, we recommend prioritizing the use of plastic mulch sheets over natural mulch. This is due to the plant’s prolonged life cycle. Plastic, biodegradable, or jute sheets provide better control over weed growth. You can find a suitable type of mulch sheet here.
Like tomatoes, cultivating eggplants requires an adequate support system. This is necessary for two reasons: first, to prevent the plant from bending and breaking; second, to keep the vegetation compact and facilitate harvesting.
For supports, we recommend a system that has yielded excellent results: wooden poles (usually chestnut) about 2.2 meters (7.2 feet) tall, arranged every 2 meters (6.6 feet) along the rows of plants. Nylon threads, thick enough to hold the plant, are then passed around these poles.
Alternatively, you can use bamboo canes for the support system, which you can find here.
Pruning of Eggplants
A recommended but lesser-known practice to ensure vigorous growth and cultivation of eggplants is the initial pruning. From the early stages of growth, eggplants develop multiple shoots, which will become the branches of our plants, many of which emerge directly from the base. It is essential to clean the plant by removing the initial shoots up to the first main branching point, creating a V-shaped structure for the plant.
Refer to the images below to better understand. In the first image, the plant appears clean and unbranched up to the first main branching point (the “V”). In contrast, the second image shows a plant that was not pruned, with many shoots growing from the bottom, now becoming branches. These branches cause confusion, no fruit development, and are more susceptible to insect attacks.
To perform this pruning, use pruning shears and gloves and proceed with this operation. The balance and productivity of your eggplant plants will be significantly improved.
Pruning, or rather a rejuvenation process like this, can be performed at different stages of growth. Remove older and damaged branches, leaving the younger, flowering branches. Usually, the lower part of the plant is the first to be pruned, while the upper part with new shoots is left with more space. This extends the life of your eggplant plants and, consequently, your harvest.
For eggplant harvesting, keep in mind a few recommendations. Firstly, remember that the plant is very spiny, and the thorns are quite venomous. If you get pricked, remove the thorns as soon as possible. It is ideal to wear gloves and use appropriate pruning shears for harvesting the fruits.
Secondly, harvest the fruits in a timely manner to avoid finding oddly developed eggplants with hardened skin and an excessive number of seeds.
Parasites and Biological Control
As you can imagine, cultivating eggplants requires an appropriate strategy for biological pest control. This cultivar is a favorite target for many garden pests. The most problematic ones include aphids (which we have already discussed in detail), red spider mites, flea beetles, and whiteflies.
For biological defense against aphids, we recommend reading our dedicated article on these insects.
Red Spider Mites
In addition to aphids, eggplants are often attacked by red spider mites, a pest that can cause significant damage if not adequately controlled. To defend against mites, you can use a frequent and alternating application of garlic infusion and nettle macerate. Another natural remedy to combat red spider mites is to spray the plants with cold water, which limits the development of new generations.
For spraying the macerates and water on the plants (to be done during the cooler hours of the day), we recommend using a backpack sprayer like the one you can find here. The use of a sprayer ensures even distribution of the liquid over the plant’s surface.
Another troublesome insect for eggplant cultivation is the flea beetle. The challenge of biological pest control against this pest lies in its high mobility, making it challenging to reach. To defend against flea beetles, we recommend using sulfur powder, which effectively keeps them away. Sulfur powder is an efficient repellent for this insect. Use it together with a blower to apply the powder on the plants.
In case of infestation, before using sulfur, you can wash the plant with natural Marseille soap. Always apply this solution during the cooler hours with a backpack sprayer. This biological treatment will help eliminate the sticky substance left by flea beetles.
Finally, another effective biological pest control technique against several pests is the mechanical removal of affected leaves. Eggplant plants are quite resilient and can tolerate the removal of leaves quite well. By cultivating eggplants, you benefit from the plant’s ability to regenerate quickly. This way, you can eliminate major focal points of pest infestations.
In addition to pests, you must also consider biological defense against cryptogamic diseases. These include powdery mildew and downy mildew. We have already discussed these diseases in detail in our dedicated posts, which we recommend referring to for preventive and defensive strategies.
- J Agric Food Chem – “Chemistry and anticarcinogenic mechanisms of glycoalkaloids produced by eggplants, potatoes, and tomatoes” – This review discusses the chemistry and anticarcinogenic mechanisms of glycoalkaloids found in eggplants, potatoes, and tomatoes. It explores the exposure of cancer cells to these compounds and their effects.
- Iran J Biotechnol – “Green Nanoparticles Engineering on Root-knot Nematode Infecting Eggplants and Their Effect on Plant DNA Modification” – This research article focuses on the nematicidal effect of green nanoparticles on eggplants. It evaluates the effect on controlling root-knot nematode and its impact on plant DNA modification.
- Methods Mol Biol – “Androgenesis in Solanaceae” – This article discusses the importance of various solanaceous species, including eggplant, in worldwide agriculture. It explores the methods and applications of androgenesis in these plants.
- Microbiologyopen – “Eating eggplants as a cucurbit feeder: Dietary shifts affect the gut microbiome of the melon fly Zeugodacus cucurbitae” – This study explores how the gut microbiome composition changes in the melon fly when feeding on eggplants, a noncucurbit host.
- Food Res Int – “Characterization and discrimination of two varieties of eggplants using multi-element and metabolomics profiles coupled with chemometrics analysis” – This research characterizes and discriminates two varieties of eggplants using various analytical techniques, providing insights into their differences.
- Photosynth Res – “Hybrid AI model for estimating the canopy photosynthesis of eggplants” – This article presents a hybrid AI model for predicting the diurnal cycles of canopy photosynthesis in eggplants, demonstrating successful predictions with a small training dataset.
- J Basic Microbiol – “AMF and PSB applications modulated the biochemical and mineral content of the eggplants” – This study investigates the beneficial role of phosphate solubilizing bacteria (PSB) and arbuscular mycorrhizal fungi (AMF) in improving eggplant fruits’ biochemical composition and mineral content.
- PLoS One – “Purpureocillium lilacinum for plant growth promotion and biocontrol against root-knot nematodes infecting eggplant” – This research demonstrates how P. lilacinum can be used for plant growth promotion and biocontrol against root-knot nematodes in eggplants.
- Mdpi – “Effects of ascorbic acid and high oxygen modified atmosphere packaging during storage of fresh-cut eggplants” – This article explores the use of ascorbic acid dip and high O2 modified atmosphere packaging to alleviate browning and quality loss in fresh-cut eggplants.
- McGill University – “Eggplants Contain Nicotine” – Eggplant seeds contain nicotinoid alkaloids, responsible for the slightly bitter taste of the purple berry.
- University of Florida, Institute of Food and Agricultural Sciences – “Eggplant – Gardening Solutions” – This article describes edible eggplant, S. melongena, and how it can be grown in the Florida summer garden.
- Michigan State University Health4U – “Eggplants” – Unpeeled eggplants are high in antioxidants and a good source of fiber, according to Peggy Crum MA, RD.
- Iowa State University – “The Not So “Bitter” Truth About Eggplant” – Eggplant, also called an aubergine, is now in season as a ‘fresh from the garden’ vegetable.
- University of Missouri Extension – “Eggplant Production, G6369” – Learn how to grow eggplant, including cultivar selection, planting, fertilizing, staking, harvesting, and insect pest management.
- University of Kafrelsheikh, Egypt – “World Vegetable Center Eggplant Collection: Origin” – This article discusses the origin and diversity of the World Vegetable Center’s eggplant collection.
- University of Missouri Environment and Garden News – “Year of the Eggplant” – Gardens and markets are filled with eggplants in a variety of sizes from small to large.