CORVALLIS, Ore. – Eggplants are tropical in origin and sensitive to cool temperatures. They will not grow much or set fruit unless night temperatures stay mostly above 50 degrees.
Eggplant "starts" are young plants with six to seven leaves. The best time to plant young eggplant starts in Oregon gardens is mid-May to mid-June, depending on where you live, the varieties you plant and the microclimate of your gardening site, says Jim Myers, Oregon State University professor of vegetable breeding.
If you live in either a coastal area or the mountain and plateaus of central and eastern Oregon, you must help young eggplants along with a heat enhancer such as a cloche, plastic soil mulch, spun fiber row cover (example: Remay), or wall-o-water. Or, make your own cloche or hot cap using a gallon plastic milk jug with the bottom cut out. Cover your eggplant starts until the first hot stretch of summer.
Plant eggplant starts about two feet from each other in a fertile soil. Four to six plants should produce enough eggplants for a family of four. Eggplants take about nine to 11 weeks of warmer weather to produce harvestable fruits.
A common mistake is to harvest eggplants too late. Eggplant should be harvested after they reach the proper size and color for their type, but before their fruit becomes seedy.
"The luster of the skin is a good indicator of readiness for harvest," said Myers. "If they are glossy, the fruit should be good. If the skin looks dull, then it is over the hill. If left on the plant too long, they will become tough and off-flavored."
The main disease problem with growing eggplants in Oregon is verticillium, said Myers.
"There's not much we can do about it, though," he said. "It causes leaf browning and necrosis (tissue death) that is evident at the end of the growing season. All varieties are susceptible, some more than others. The list below includes those that have better tolerance for verticillium."
The OSU Extension Service recommends the following varieties of eggplants as growing well in most areas of Oregon, except at the coast or the higher elevations of the state, where a protective cloche is needed.
Dusky, Epic, Bambino, Cloud Nine, Calliope, Burpee Hybrid, Millionaire, Classic, Lavender Touch, Megal, Bride and Orient Express.