Eggplant

History

The eggplant is a member of the Solanaceae family, also known as the nightshade family, which includes crops such as the Irish potato, tomato, tomatillo, and pepper (see Figure 1).

Eggplant is thought to have originated in Asia (mainly parts of India and Burma/Myanmar). The first record of this vegetable is from a 5^th-century Chinese book. The original eggplant was a wild plant with orange, pea-sized, spiny fruit (see Figure 2) — very different from present-day eggplant!

Using newly established trade routes, the Arabs and Persians likely brought the eggplant to Africa around the 8^th century, and then the Moors to Spain around the 12^th century. It was a common vegetable in northern Europe by the 16^th century. When Spaniards colonized the New World, eggplant was transported along with many new crops. Eggplant was documented in Brazil by 1650. By the 1800s, ornamental eggplant varieties were grown in the U.S., introduced by Thomas Jefferson. It wasn’t until the 1900s that other varieties were grown for consumption. See Figure 3.

Another name for an eggplant is aubergine (preferred in the U.K., Ireland, and France) or brinjal (preferred in South Asia and Africa). Eggplant was once called the “mad apple” and considered to cause insanity, and was also known as the “apple of love” since it was believed to have the properties of a love potion. Today, eggplant is most popular in Asia where leading producers include China and India.

Eggplant are annuals (with a life cycle of one year) that require a long, warm growing season. Very tolerant of hot weather, many eggplant varieties are highly suitable to the Louisiana climate.

Varieties

Eggplant can be grouped into three main types: (1) Asian, (2) Italian, and (3) miniature or specialty (see Figure 4). These types vary in shape, size, and mature fruit color (such as purple, white, orange, red, or green). Asian varieties generally produce elongated, purple-hued fruit, and also include smaller, round varieties ranging in color from purple and green to white. Italian varieties are the more traditional eggplant, producing medium-sized and oval fruit in various shades of purple. Miniature or specialty eggplant varieties are smaller in size and are often very attractive and superior in taste. Some Asian varieties can also be grown as miniature eggplants.

Eggplants have either open-pollinated (including heirloom) or hyrbid varieties. Some eggplants are heirloom varieties, like Rosa Bianca, meaning the seeds have been saved for at least 50 years, can be saved each season and replanted, and are open-pollinated.

Eggplants produce perfect flowers (both male and female parts in each flower), which may be cross-pollinated, but open-pollinated is more common. Flowers generally remain open for 2 or 3 days and are most receptive to pollination in the morning. The extent of natural crossing depends upon insect activity. If seed saving, different varieties should be separated by a distance of 300-1,600 feet to avoid cross-pollination. Generally, it is not recommended to save seed for future planting with hybrid varieties, as they are usually not expressed properly in the next generation.

See the recommended eggplant varieties for Louisiana in Table 1.

Table 1. Recommended Eggplant Varieties for Louisiana

When and How to Plant

Eggplant seeds should be started inside 8-10 weeks before the desired transplanting dates (see the Eggplant Planting Guide, Table 2). Seeds will germinate best in warm soil temperatures (75-90 degrees F) and will take longer to germinate in cooler soil (keep above 60 degrees F). Using seed germination trays (with at least 1.5-inch diameter cells), plant one seed per cell at a shallow depth, about 1/8-1/4 inch deep, just deep enough to be covered with a thin layer of soilless potting mix. Make sure to keep the seed trays in a well-lit area above 70 degrees F. Keep soil moist, which usually requires daily light watering. A seedling heat mat and plastic dome lid are helpful in maintaining ideal germination conditions.

A few days before transplanting outside, it is recommended to follow a hardening-off process to transition seedlings to outdoor conditions. Eggplant easily survives transplanting, but seedlings are susceptible to cold-shock and growth may be stunted if soil and air temperatures are too low. Aim to transplant outside 1-2 weeks after the last frost date and when the daytime/nighttime temperatures are around 70-85 degrees F during the day and 65 degrees F at night (there should be no danger of frost). Transplants should be 6-8 inches tall. Refer to the Eggplant Planting Guide (Table 2) for the recommended spacing when transplanting. The expected growing season for eggplant is 2-3 months (this is how long they will continue to bear fruit).

Table 2. EGGPLANT PLANTING GUIDE

Where to Plant

Since eggplant is a warm season crop, it requires warm soil and full sun (at least 6 hours/day). Eggplant prefers well-drained, sandy loam soil with a pH between 6.0 and 6.8. It is recommended to plant eggplant in box beds or in traditional raised garden rows that are about 12 inches tall to ensure good drainage. In all types of gardens, it is recommended to add a layer of compost, peat moss, rotted hay, or other organic matter and mix into the soil to optimize plant health.

Reflective plastic mulch — or a plastic fabric/film — is recommended to deter aphids that transmit viruses, as well as to increase soil temperature and control weeds. Drip irrigation is also recommended when using plastic mulch to maintain ideal soil moisture and to encourage productive plants.

Each season, rotate plant families — avoid planting crops from the same plant family in the same area of the garden — to reduce disease and pests. A longer crop rotation is recommended for Solanaceae crops to avoid Verticillium wilt disease.

Plant Care

Watering

To prevent a bitter-tasting eggplant, make sure the soil has adequate moisture and irrigate during dry and hot weather. Consistent watering of about 1 inch per week is recommended, using a thorough soaking to promote deep root growth. Increase watering during high temperatures and high winds, or for sandy soils.

Fertilization

Eggplants may produce small, misshapen fruits if inadequately supplied with nitrogen. Like many solanaceous crops, they are prone to blossom-end rot, a disorder resulting from calcium deficiency. This may be due to inconsistent watering, which may cause calcium to be poorly dissolved in the soil for uptake. If blossom-end rot persists with even watering, conduct a soil test, and discuss the results with a local county extension agent.

Organic fertilizers such as compost, fish emulsion, composted poultry litter or manure, worm castings, and blood or bone meal originate from living organisms. They are far more environmentally sustainable and safe than traditional synthetic fertilizers. They naturally release nutrients more slowly and over a longer period of time. When applying organic fertilizer, it is important to use in unison with compost, cover crops, and crop rotation, which all work together to build soil health. Learn how to convert inorganic fertilizer recommendations to organic fertilizers here.

Alternatively, a synthetic fertilizer may be used at a rate of about 1.25 lbs (2.5 cups) of 13-13-13 for every 25 feet of row or 75 square feet. Broadcast, or sprinkle evenly, over the soil before planting and then mix in about 3-6 inches deep using a rake. Supplemental sidedressing, or reapplication of synthetic fertilizer, is recommended when the first immature fruits are visible. Sidedressing is the addition of a small amount of fertilizer to the soil around already established plants when the plant begins to fruit or vine, primarily to provide nitrogen. When using synthetic fertilizer, sprinkle 2 tablespoons around each plant, keeping it about 6 inches away from the plant stem; water into the soil. Additional sidedressing may be applied every 3-4 weeks to keep this long season crop productive. Fish emulsion is a good, fast-release source of nitrogen for sidedressing if an organic fertilizer is preferred.

Support

It is recommended to stake and trellis eggplant as it grows to avoid collapsing and falling over due to the weight of the fruit, and to prevent wind damage. Staking will also improve yield and fruit quality. The recommended, most effective staking and trellising method is the Florida Weave Technique. Place a metal T-post at the end of each row and one in the middle; then place squared wooden stakes between every few eggplants. When the plants are 12-15 inches tall, use garden or butcher twine to weave between each plant (about 10 inches above the soil) on both sides and tie the twine to the stakes. In this method, the plant is never tied to the twine or stake. It is recommended to do one more level of trellising when the plants have grown another 12-15 inches, about 10 inches above the last support weave. Watch this helpful video tutorial on the Florida Weave System (skip to 4:00 for eggplant-specific trellising).

Weeds

Plastic mulch will control most of the weeds; hand-pull weeds close to the plant, especially in the planting holes.

Insect Pests and Diseases

Eggplants are hardy and can withstand moderate insect pressure, but regular garden monitoring is recommended to identify insect pest issues. Common insect pests for eggplants include aphids, whiteflies, flea beetles, cutworms, and red spider mites. Most eggplant diseases are caused by fungus due to high humidity and moderate temperatures. Generally, prevent diseases by selecting disease-resistant eggplant varieties; rotating crops; following the recommended spacing and watering; and removing diseased plants. Common diseases for eggplants include blight, leaf spot, Phomopsis fruit rot, and Verticillium wilt. See Table 3 to aid in diagnosis and management of some common eggplant insect pests and diseases.

Table 3. Organic and Natural Management for Common Eggplant Insect Pests and Diseases

Harvest and Storage

Harvest eggplant throughout the summer when the skin is glossy and the fruit reaches the approximate harvest size (it’s better to harvest young than to have overmatured fruit). A good test is to press the fruit with the thumb: if the flesh bounces back, it’s ready to harvest; if it’s firm and hard, it’s too young. Clip the fruit, leaving a small stem attached (1/2 inch), using a knife or shears (avoid twisting/breaking the stems). Wear gloves when harvesting eggplant, since the stem and calyx (green top of the eggplant) often have prickly thorns. Keep plants well-picked (harvest once or twice a week) and remove overmatured or poor-quality fruit to encourage high productivity.

Eggplants can be stored in the refrigerator for 5-7 days (ideal storage temperature is 46-54 degrees F, with 90-95% relative humidity). Do not cut the fruit until you are ready to use it, as eggplant will quickly turn brown. The fruits also bruise easily, so avoid overhandling.

Preserve eggplant by freezing raw or cooked (blanched or fried) slices in freezer bags for up to 8 months.

Eggplant is Nutritious and Good for You

Good source of dietary fiber

Important for bowel health, lowering cholesterol, controlling blood sugar, and maintaining a healthy weight

High in Potassium

Essential for body function, especially the heart, kidney, nerves, bones

Recipes

Louisiana Harvest of the Month: Eggplant Parmesan

Common methods of preparing and cooking eggplant

Video on how to cut an eggplant

Taste-testing ideas: baked crispy eggplant sticks with marinara sauce, eggplant dip (baba ghanoush) with pita wedges, ratatouille

Other websites with many eggplant recipes:

USDA MyPlate Kitchen

SNAP-Ed San Francisco

SNAP-Ed Arizona

Produce for Better Health Foundation

Sources

• Southeastern Vegetable Extension Workers, 2020 Southeastern U.S. Vegetable Crop Handbook
• LSU AgCenter, Louisiana Vegetable Planting Guide
• LSU AgCenter, Louisiana Commercial Vegetable Production Recommendations
• LSU AgCenter, Vegetable Gardening Tips: Eggplants
• UF Extension, Planting Guide
• UF Extension, Vegetable Production Handbook of Florida
• Texas A&M AgriLife Extension, Easy Gardening: Eggplant
• Texas A&M AgriLife Extension, Vegetable Varieties for Central Texas
• Alabama A&M & Auburn Universities Extension, Integrated Pest Management
• UMass Extension Vegetable Program: Disease, Insect, and Mites Fact Sheets
• Alabama A&M & Auburn Universities Extension, Crop Production
• University of Illinois Extension, Eggplant
• UA Cooperative Extension, The Elegant Eggplant
• Purdue University, History and Iconography of Eggplant
• UC Davis, Home Vegetable Gardening: Eggplant
• USDA SNAP-Ed Connection: Eggplant
• Purdue Extension FoodLink: Eggplant
• Maynard, Donald N & Hochmuth, George J (2007). Knott’s Handbook for Vegetable Growers (5th edition). John Wiley & Sons, Inc.
• Decoteau, Dennis R (2000). Vegetable Crops. Prentice-Hall, Inc.
• Swiader, John M & Ware, George W (2002). Producing Vegetable Crops (5th edition). Interstate Publishers, Inc.
• Sukprakarn, S, Juntakool, S, Huang, R, and Kalb, T (2005). Saving your own vegetable seeds—a guide for farmers. AVRDC publication number 05-647. AVRDC—The World Vegetable Center, Shanhua, Taiwan. 25 pp.
• Seed Savers Exchange, Seed Saving: A Guide to Isolation Distances
• University of Georgia Extension, How to Convert an Inorganic Fertilizer Recommendation to an Organic One, Circular 853