A   B O U N T I F U L   G A R D E N

---

The Elegant Eggplant

by Linda Trujillo,
Master Gardener

Botanical Name
Solanum melongena, Solanum integrifolium, Solanum gilo

Common Names
Eggplant, eggfruit, aubergine, brinjal, tomato-fruited eggplant, gilos, guinea squash, mad apple, nasubi

Origin, History and Folklore
Eggplant is a member of the Solanaceae or nightshade family, which includes tomatoes, potatoes, and peppers. Its origin is considered to be India where it continues to grow wild. This spiny, bitter, orange, pea-sized fruit has been cultivated throughout India and China for more than 1500 years.

As trade routes opened, eggplant was introduced to Europe by the Arabs and transported to Africa by the Persians. The Spaniards carried it with them to the New World and, by the early 1800s, both white and purple varieties could be found in American gardens.

According to the American Horticultural Society Encyclopedia of Gardening -- Vegetables, "A 5th Century Chinese book contains one of the oldest references to eggplant. A black dye was made from the plant, and ladies of fashion used it to stain their teeth - which, when polished, gleamed like metal."

In China, as part of her "bride price," a woman must have at least 12 eggplant recipes prior to her wedding day. In Turkey, "imam bayeldi," a tasty treat of stuffed eggplant simmered in olive oil is said to have made a religious leader swoon in ecstasy. When first introduced in Italy, people believed that anyone who ate the "mad apple" was sure to go insane.

Description
Eggplant is a frost tender, heat loving, branching bushy plant with thick, woody stems. The green to grayish green leaves are large, lobed, and alternate with the underside typically covered with spiny fuzz. Mature plants range from 1 to 8 feet in height. Although eggplant is a perennial, it is more commonly grown as an annual.

Eggplant flowers are star-shaped in various shades of purple and usually form on opposite leaves as either solitary blooms or grouped in clusters of two or more. They are perfect and primarily self-pollinating. However, some cross-pollination can occur with the help of bees, ants and other insects. Flowering is thought to be day neutral and, therefore, not dependent on a specific number of daylight hours.

Solanum melongena is the more commonly recognized eggplant. There are many sizes and shapes of fruit, with skin colors ranging from blackish purple to florescent purplish green to gold or white. In addition, some varieties produce lovely bicolor or striped skin. The fruit has a dense, uniform and firm, white, sweet flesh.

The standard eggplant is an oval or pear-shaped, glossy, purplish fruit 6 to 9 inches long. Japanese and oriental varieties tend to be elongated and slender with a thinner, more delicate skin. "Ornamental" varieties are edible and tend to produce small, white-skinned, oval-shaped fruit.

The purplish black color found in eggplant skin is the result of a water-soluble flavonoid pigment, anthocyanin, which is also responsible for the red, purple and blue coloring in flowers, fruits and vegetables.

Fruit of the Solanum integrifolium and S. gilo lack a solid interior and resemble their tomato relatives. The "tomato-fruited eggplant" plant ranges in height to about 4 feet and typically bears fruit that is 2 inches in diameter or less. Common skin colors range in hues of green, red or orange, as well as bicolor or striped.

How to Grow
Eggplant is easy to grow in the low desert southwest. It does well in a variety of soil textures, but prefers rich, well-drained soil with a pH of 5.5 to 6.5. It thrives in full sun and requires at least five months of warm weather for fruit production.

The optimum daytime growing temperature ranges between 70°F and 85°F. When temperatures rise above 95°F, eggplant ceases to set fruit and may drop flowers or abort immature fruit. Fruit set is also reduced when temperatures fall below 60°F.

Because eggplant requires a long growing season, gardeners typically set out transplants in March once danger of frost has passed and daytime temperatures are consistently above 70°F.

A gentle reminder here - temperatures below 50°F can damage these tropical natives so, if an unexpected cold spell hits, cover the plants to provide protection.

One way to get transplants is to purchase them from local, reliable plant nurseries. Look for healthy, sturdy, bushy plants with no flowers or fruit. Eggplant does not like to have its roots disturbed, so check to make sure the plant is not root bound.

The second way to get transplants is to grow your own from seed. There is an exciting assortment of eggplant varieties, and choosing to grow your own expands your gardening and culinary horizons.

Start seed indoors in January, 4 to 8 weeks prior to planting. Sow seeds 1/4 to 1/2 inch deep in flats or seed pots filled with rich soil mixture. Seeds usually germinate in 7 to 14 days, depending on environmental conditions and the age of the seed.

Germination temperatures range from 70°F to 90°F, so it is important to keep the soil warm. You may need to provide bottom heat and/or cover the flats or pots to maintain soil temperatures.

Adequate moisture is essential to germination. Try misting, rather than watering, to maintain soil moisture and keep seeds from washing away or becoming too deeply buried. Once seedlings emerge, continue to keep the soil warm and moist, but not soggy.

To encourage compact, bushy growth, provide seedlings with 12 to 14 hours of bright light, whether natural or artificial. In addition, you may need to apply fertilizer if it is not included in your potting mix.

Transplant seedlings into prepared garden beds, spacing plants 18 to 24 inches from each other, in rows 30 to 36 inches apart. Eggplant is a heavy feeder. Side dress when plants reach about half their mature size, and again when the first fruit is harvested. Although most plants are self-supporting, plants heavy with fruit benefit from some support.

Eggplants prefer consistent soil moisture, but once established can tolerate dry spells. Although the majority of water- and nutrient-absorbing roots are found in the top 18 inches of soil, roots can reach a depth of 4 feet. To avoid flower and fruit drop, water deeply and regularly, especially during long, dry periods.

To conserve soil moisture, try planting in waffle beds or applying a 2- to 3-inch layer of mulch around the base of each plant. To minimize sun scald during the hot, intense days of summer, provide a bit of midday sun protection. Depending on your garden's location and layout, shade can be provided by tall, nearby plants or by shade cloth. Eggplant can be grown successfully in containers. Choose smaller plant varieties and large containers with good drainage. Be prepared to water more often, since the soil tends to dry out more quickly.

Varieties and Seed Sources
Choose varieties that reflect your gardening and eating preferences. My personal favorite, the oriental variety "Ichiban," produces abundant, tender, sweet, purple-skinned fruit that I harvest when 4 to 6 inches long. It is easy to grow and works well with my favorite recipes. This year I also plan to add a "tomato-fruited" variety.

Most local plant nurseries or mail order seed houses offer a selection of eggplant. My favorite mail order seed houses are Seeds of Change, Seed Savers Exchange, Bountiful Gardens, and Botanical Interests because they provide a wonderful variety, as well as organic options. Limited selections by Seeds of Change and Botanical Interests can be found locally at Whole Foods.

Pests and Diseases
Eggplant is susceptible to verticillium wilt and the best defense is to rotate plantings and choose resistant varieties. Pests include flea beetles, aphids, lace bugs, whiteflies, and red spider mites.

The University of California Davis, Vegetable Research and Information Center provides a guide for diagnosing eggplant problems that can be accessed online at http://vric.ucdavis.edu/veginfo/commodity/garden/crops/eggplant.pdf.

When to Harvest and How to Store
Eggplant fruit is edible once it reaches one-third its mature size and, as with many edible plants, regular harvest helps maintain consistent fruit production. Since the stems are thick, tough, and spiny, fruit should be cut off using pruning shears or a sharp knife.

I prefer small, tender fruit and usually harvest my eggplant before it reaches two-thirds its mature size. The key things to look for are a bright, shiny, smooth skin and fruit that firm to the touch. Eggplants with dull skin and soft, wrinkled fruit are over-ripe and, although edible, may be bitter and full of hard brownish black seeds. Over-ripe fruit can be used to save seed.

Eggplant does not store well, even under the best of circumstances, so plan to use it soon after harvesting. It can be stored overnight at room temperature. If longer storage is necessary, don't refrigerate this tropical native because it suffers when kept too cold. Ideal storage temperature is about 50°F. Another way to help extend the storage life of eggplant is to avoid storing it with ethylene-producing fruits such as apples, bananas, melons or tomatoes.

Seed Saving
Eggplant seeds maintain 50% germination for 7 years. The process for harvesting and saving seed is detailed in Susan Ashworth's book Seed to Seed.

Uses
Eggplant is versatile and can be roasted, grilled, baked, stewed, stuffed, dried, braised, mashed, pickled, pureed, or breaded and fried. It is an essential ingredient in Italian ratatouille and Middle Eastern babaganoush.

Eggplant is one of the "sponges" of the edible kingdom and "salting" or "soaking" prior to cooking help reduce its natural absorption tendencies and removes any lingering bitterness.

Nutritional Value
By itself, eggplant has nominal nutritional value. However, it is eggplant's natural ability to absorb that makes it a nutritional asset to the foods it is prepared with. A serving of 1/2 cup, cubed, boiled eggplant provides 13 calories, 0.1g fat, no cholesterol, 2mg sodium, 0.4g protein, 3.2g carbohydrate and 119g potassium.

Health Benefits and Concerns
When harvesting eggplant, some people may experience sneezing or develop skin irritations as a result of contact with the leaf fuzz and spiny calyx (fruit cap).

References: Ashworth, Suzanne. "Growing Eggplants Successfully," Tauton's Kitchen Gardener June/July 2000 (pp. 24-28). An excellent article containing detailed instructions on how she germinates eggplant seeds.

Ashworth, Suzanne. Seed to Seed. ISBN 0-9613977-7-2 (pp. 157-159).

Madison, Deborah. Vegetarian Cooking for Everyone. ISBN 0-7679-0014-6 (pp. 279, 366-371).

University of California Publication 7235, "Eggplant Production in California." http://anrcatalog.ucdavis.edu/pdf/7235.pdf


Maricopa County Master Gardener Volunteer Information
Last Updated January 25, 2003
Author: Lucy K. Bradley, Extension Agent Urban Horticulture, University of Arizona Cooperative Extension, Maricopa County
© 1997 The University of Arizona, College of Agriculture and Life Sciences, Cooperative Extension in Maricopa County
Comments to Maricopa-hort@ag.arizona.edu 4341 E. Broadway Road, Phoenix, AZ 85040,
Voice: (602) 470-8086 ext. 301, Fax (602) 470-8092