Eggplant (family Solanaceae; Solanum melongena) is thought to have originated in Southern to Southeastern Asia. Eggplant is closely related to pepper, tomato, tobacco and potato, and shares diseases with some of these crops. Cultivation methods are similar to those for pepper, but it is more heat tolerant and cold sensitive. Deep, well-drained sandy loam soils are ideal for eggplant. Southern slopes that warm early in the spring may yield better.
Types and Varieties
Eggplants come in a diverse array of shapes, colors and sizes, and preferences vary widely among markets. The most common type is large, oblong, and deep purple with a green calyx. Asian types are long and slender, often deep purple with purple calyxes. Specialty varieties include finger-sized eggplants, small round eggplants, and different colors in all shapes and sizes. Some varieties are marketed specifically for tunnel or greenhouse production.
|Oblong Large-Fruited||Slender Long Asian|
|Angela (striped) - GH||Orient Express|
|Aretussa (white) - GH||Millionaire|
|Black Bell||Slender Finger|
|Clara (white)||Gretel (white)|
|Dancer (pink)||Fairy Tale (striped)|
|Jaylo - GH|
|Michal - GH|
|White Lightning (white)|
|GH: developed for tunnel or greenhouse production|
Apply lime according to soil test results to maintain soil pH at 6.5-6.8.
Use a liquid starter fertilizer at transplanting, especially with cool soil conditions. Use a high phosphorus starter fertilizer mixed according to label directions (typically 3 lb/50 gal of water). Apply 8 fl oz (1 cup) per transplant. If plants are to be grown on plastic mulch, the amount of nitrogen fertilizer to be sidedressed can be reduced, since leaching is minimized. Nitrogen can be applied through drip/trickle or overhead irrigation. Drip fertigation is especially advantageous with plastic mulch. Too much nitrogen fertilization will lead to plants that are bushy, leafy and slow to bear fruit. See the sections, Plastic Mulch and Row Covers and High Tunnels, for more information.
Less nitrogen fertilizer will be needed if legume sod was plowed down or if manure was applied (see Table 1 and Table 7).
|PLANT NUTRIENT RECOMMENDATION ACCORDING TO SOIL TEST RESULTS FOR EGGPLANT|
|EGGPLANT||NITROGEN (N) LB PER ACRE||PHOSPHORUS (P) LB P2O5 PER ACRE||POTASSIUM (K) LB K2O PER ACRE|
|SOIL TEST RESULTS||VERY LOW||LOW||OPTIMUM||ABOVE OPTIMUM||VERY LOW||LOW||OPTIMUM||ABOVE OPTIMUM|
|Broadcast and Incorporate||50||150||100||25-50||0||150||100||50||0|
|Sidedress 3-4 Weeks after Planting||30-50||0||0||0||0||0||0||0||0|
Eggplant is normally grown from transplants. Between 2 and 4 ounces of seed are required to produce plants for one acre. Germinate seeds in flats at 70-75ºF. Move to 50-cell trays after emergence. Sowing directly into 50-cell trays will shorten the time needed to produce transplants by approximately 1 week. Good transplants are 6-8 weeks old, fairly large and slightly hardened. Transplant in the field with 18" (small plant types) to 30" (large plant types) between plants. This requires from 66-40 plants per 100' of row respectively. Allow 36-42" between rows. Eggplants are much less cold hardy than tomatoes. Plant eggplants out after overnight low temperatures are consistently above 50ºF.
The use of black plastic mulch will usually result in increased early growth and yield with less damage from Verticillium wilt, perhaps because the plant is more healthy and vigorous at the time of infection. Eggplant benefits from irrigation during the period of flowering and fruit set. If soil moisture is limited at this time, yields will be reduced. Large plants may benefit from being staked. Use one 4.5' stake per plant. Temperatures above 90ºF, and night temperatures below 60ºF or above 70ºF, can cause poor flowering and flowers drop. Fruit are also vulnerable to sunburn so enough leaf coverage is critical.
When growing eggplant in a high tunnel or greenhouse, consider trellising to prevent plants from toppling and improve ease of harvesting later in the season. Pruning to a two- or four-leader system may improve yields, although labor cost tradeoffs should be considered for your farm.
Harvest and Storage
Fruit should be harvested by clipping them off with sharp shears when the outside color is a glossy purple, the fruit is firm and before the seed changes color. Soft fruit, loss of glossy color and dark colored seed are signs of over-maturity. Harvest fruit as they mature to ensure continued fruit set. Fruit can be stored up to 10 days at 50-54ºF and 90-95% relative humidity. Eggplant are susceptible to chilling injury if held in temperatures that are too cold.