Taking an environmentally sensitive approach to pest management
The National Garden Bureau selects a vegetable to promote each year and 2008 has been designated by that organization as “the year of the eggplant”. In the past it was thought to cause a wide array of harmful effects in humans ranging from pimples to insanity. Today, eggplant is appreciated for both its inspiring beauty and delightful flavor. An essential ingredient in cuisines around the world, it is the essence of Greek moussaka, Middle Eastern baba ganoush, Italian eggplant parmigiana, and French ratatouille. The emergence of Asian cuisine has introduced a whole new range of eggplants flavoring delicious stir-fries and curries. Gardens and markets are filled with eggplants in a variety of sizes from small and pea-like, to egg shaped, to long and slender. Their fruits offer a stunning array of colors from the traditional royal purple to shades of rose, violet, green, yellow and white, often enhanced with lovely stripes in a contrasting color.
Eggplant (Solanum melongena L.) is believed to have originated in India and was cultivated in China as early as 500 B.C. Eaten in the Middle East and Asia for centuries, it was taken to Africa by the Arabs and Persians during the Middle Ages, eventually finding its way to Italy in the 14th century. Even though eggplants were consumed without hesitation in other parts of the world, it was not eaten by all Europeans. In fact it was called mala insana (mad apple or bad egg). The fruit was considered dangerous because it belonged to the nightshade family (Solanaceae) which contains many poisonous plants including jimson weed, angel’s trumpet, belladonna and deadly nightshade.
Louis XIV, during his reign in the 1600’s, was among the first in Europe to introduce eggplant to the table. Unfortunately, the fruit was not well received and was said to “be as large as pears, but with bad qualities.” It was also thought that eating eggplant caused fever, epilepsy and even insanity. For more than a century eggplants were grown for their ornamental value by the Europeans who prized the plant’s beautiful purple, star-shaped flowers and colorful fruits but found its bitter flavor unappealing.
Thomas Jefferson introduced eggplant into the United States in the early 1800’s. An avid gardener, Jefferson was interested in discovering new plants and grew many flowers and vegetables from around the world in his gardens at Monticello. Because of its botanical connection to other poisonous plants, eggplant largely remained an ornamental curiosity until the late 1800’s and early 1900’s. Immigrants arriving in America from China and Italy brought with them a long and rich tradition of using eggplants in their cuisine and helped to promote approval of the eggplant in North America as a culinary item.
Eggplant probably got its English common name from John Gerard, a noted herbalist, who described eggplants growing during the 16th century as having “the bignesse of a Swans egge, and sometimes much greater, of a white colour, sometimes yellow and often browne.” Around the world it goes by a variety of other common names. In its native India eggplant is known as brinjal. In Britain, France and other parts of Europe, it is called aubergine. Italians call it melanzana while the Greeks know it as melitzana. Australians refer to it as eggfruit and in Africa the eggplant is called a garden egg. These many names reflect the rich diversity of eggplant varieties available today.
In nature eggplants are frost-tender, herbaceous perennials but most gardeners treat them as annuals. Their branched plants reach 2-4 feet in height and are covered with hairy leaves, sometimes having tiny spines. They bear attractive, star-shaped flowers that usually are purple, sometimes white, and produce edible fruit that may be black, purple, green, white, yellow, orange or red, sometimes striped or shaded. The flesh of eggplant is creamy white and speckled with tiny brown seeds. Harvest dates vary from 45 to 90 days after transplanting seedlings into the garden.
Eggplants are generally classified by the shape of their fruit into one of five basic groups: globe, elongated or cylindrical, egg-shaped, specialty and pea eggplants. Each category offers a choice of eggplants in varying colors, sizes and days to harvest. In the variety descriptions the number of days from transplanting to harvest is shown in parentheses.
The most common type in North America is the Western or oval eggplant that has large, deep purple, pear-shaped fruits. This type is most commonly used for stuffing, baking, sautéing and grilling. Unfortunately, it has the undeserved reputation for having tough skin and bitter flavor, generally not a problem when harvested at proper stage of maturity.
Japanese varieties are typically small-fruited with a variety of shapes, and thin skins in beautiful, deep purple or light violet colors, sometimes blended with white or green. The skin is so tender that fruits don’t need to be peeled before consumption. These varieties are ideal for stir-frying, grilling, sautéing and pickling.
Recently, two varieties of eggplant received the prestigious All-America Selections Award. Both have excellent flavor and texture, are highly productive over a long harvest period. ‘Fairy Tale’ hybrid (51 days) won the award in 2005 for its attractive white fruits striped in violet and purple shades. Fruits can be picked when small (1-2 ounces) for a unique miniature eggplant, or left on the plant to double in size without losing any flavor or tenderness. Compact plants make this variety ideal for growing in containers. ‘Hansel’ hybrid (55 days) is a 2008 award winner that produces clusters of glossy, dark purple fruits borne over a long season on plants that out-yield traditional varieties. Fruits can be harvested when only 2-3 inches in length or left to grow to a full 6-10 inches long.
Eggplants can be started from seeds indoors or purchased as transplants ready to set out in the garden. They prefer a rich, fertile soil with plenty of organic matter. The latter can be accomplished by incorporating peat moss, well-rotted compost or manure into the soil before planting. Plant eggplants in full sun where they will receive at least 6-8 hours of direct sunlight each day. The mature size of the plant determines the correct spacing. Allow 18-24 inches between standard-sized eggplants. Smaller varieties can be planted closer together with 12-18 inch spacing between plants. In addition to warm temperatures, eggplants need regular watering, about 1 inch of water per week, to keep plants productive. A layer of organic mulch such as well-rotted compost, sawdust or straw applied around the base of the plant helps retain moisture, improve the soil and provide weed control.
Eggplants have the reputation of being a bit challenging and may require a little extra care in the garden. If nights become cool after planting outdoors in the spring, protect plants with a cover such as hot caps or fabric row cover in the evening and remove them during the daytime until the temperatures have warmed up again. Eggplants that produce large fruits can bend or break and are best staked for support. The long, slender varieties of eggplants also produce straighter fruits when staked. A small, wire tomato cage can also be used.
Flea beetle and Colorado potato beetle are eggplants most common insect pests. Holes in the leaves of eggplant often indicate damage from these troublesome pests. A fabric row cover applied at transplanting will help to exclude these pests. Spinosad (sold as SpinTor®) is a relatively new pesticide on the market that controls these two pests quite well. Because it is derived from a naturally-occurring soil microbe it is considered organic in nature and is not harmful to most beneficial insects.
Aphids often gather on the underside of leaves, on stems and young buds. They can be dislodged from the plant by washing them off with a strong stream of water, or spraying them with insecticidal soap according to label directions. Make sure to cover the underside of the leaves when applying pesticides. Since aphids can be a recurring problem check leaves regularly for signs of infestation.
Mites are another common problem that often aren’t noticed until considerable damage has been done. Mites are very small and thrive under hot, dry conditions. They damage plants by sucking on plant juices causing the leaves to discolor and yellow. When their population builds, a fine Webbing on the underside of the leaves is visible. Mites can be controlled by washing them off with water every day for about a week, or use insecticidal soap applied to the tops and undersides of leaves.
Verticillium wilt is a disease that affects eggplants, as well as tomatoes, peppers and potatoes. The disease is caused by a soil-borne fungus that causes plants to wilt, turn yellow and eventually die. Interior sections of the stem will be brown and discolored. Prevent verticillium wilt by rotating eggplant, tomato, pepper and potato plants to different areas of the garden every year so you are not planting these crops in the same soil.
Harvesting eggplants at proper state of maturity is necessary for best eating quality and maturity varies with variety. In general, large-fruited eggplants are ready to harvest 75-95 days from transplanting, while the small-fruited varieties and many of the newer hybrids are ready to harvest within 50 to 60 days of planting outdoors. Fruits should feel firm and have a glossy colored skin when harvested. Maturity can be judged by pressing lightly on the skin of the eggplant with one’s finger. If the pressed spot springs back it is ripe; if the imprint remains the fruit is overripe and will tend to be seedy and somewhat bitter.
Harvest fruits regularly to keep plants producing. Use a sharp knife or pruning shears to cut the eggplants from the plant. To prevent damaging the plant, don’t try to remove the fruit by twisting or pulling it as damage to the plant is likely to occur. In climates where the plants will die from frost, remove any new blossoms beginning about a month before the first anticipated fall frost. This will promote ripening of the existing fruits.
Eggplant fruits are best used fresh but will keep for about a week when loosely wrapped in a perforated plastic bag and stored in your refrigerator’s vegetable crisper or in a cool pantry. To preserve eggplant for later use, blanch or steam slices or cubes and store in the freezer for up to 6-8 months.
Growing eggplants in containers adds color and ornamental value to decks and patios, as well as a harvest of nourishing vegetables. Dwarf eggplant varieties grow well in an 8-inch diameter pot or even a deep window box. Larger varieties need a 12-inch diameter pot or 5-gallon container in order to have sufficient room for roots to develop. Make sure the container has drainage for excess water. Then fill with a soilless mix designed for container gardening. After transplanting check the soil regularly and water as needed, especially during the heat of summer and when eggplants begin to form on the plant. Use a water-soluble fertilizer according to label directions on a regular basis.
Eggplant is a versatile vegetable that can be prepared in a variety of ways. It is excellent grilled, stuffed, roasted, sautéed, puréed or served in soups or stews. It can also be used to make curries, stir-fries and kabobs. Some cooks recommend soaking large eggplants in water for 15 minutes before using to reduce bitterness. Others recommend peeling the skin which tends to contribute most of the bitter flavor. All varieties taste better when harvested on time, when the flesh is still springy when pressed, before becoming overripe.
Naturally low in calories, fat and sodium, eggplant is also high in fiber and an excellent source of potassium, as well as folic acid, copper, vitamin B6, vitamin A, and magnesium. To keep calories and fat low, avoid cooking eggplant in oil since it absorbs it like a sponge. If oil is used, coat eggplant with bread crumbs or a flour and egg mix prior to frying.
If you can’t remember the last time you ate eggplant, celebrate “The Year of the Eggplant” by planting a few in your garden. They offer nearly endless possibilities to try something different this year and in years to come.
Credit: National Garden Bureau
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REVISED: September 30, 2015