I'm kind of an eggplant addict. I know, it's a weird thing to be addicted to but there are few things that are as delicious as just-picked eggplant, roasted with a little olive oil, salt and pepper. It tastes completely different than eggplant that has been refrigerated and has been sitting on a store shelf.
Eggplant is easy to grow and some varieties are so beautiful they can be used as ornamentals. The flowers are gorgeous and the eggplants themselves can be sculptural.
My favorite container for the maximum yield, ease of care is to use a grow box, and my favorite type of grow box is an Earthbox. These self-watering containers provide a constant level of moisture, which is important for eggplant.
Soil - One of the great things about growing eggplant in containers is that they are a lot less likely to get the nasty soil-bourne fungus, verticillium wilt, which they are prone to and is fairly common in traditional garden soil. Eggplant needs a fast draining potting soil, but also one that won't dry out too fast. If you are using a very light soil, you will have to water enough times during the day so that they soil doesn't completely dry out--in the heat of the summer, depending on your pot size soil, that may mean watering twice a day or more. Your goal is to keep the soil moist, not soaking wet. If you are growing eggplant in a pot or container, it is also a good idea to use some type of mulch, like straw or wood chips to cover the soil, which helps to keep the soil moist.
Fertilizer - Eggplant are fairly heavy feeders. I mix an all purpose fertilizer into my potting soil at the beginning of the season and then do supplemental feeding with a diluted liquid fertilizer every other week during the growing season. However if you are using a grow box system, you will only need to fertilize at the beginning of the season, according to the directions.
Sun - Eggplants are sun lovers. Make sure they get at least six hours of unobstructed sun per day and the more sun the better. Eggplant, like tomatoes also are heat lovers. One of the reasons grow boxes work particularly well for me, living in a cold climate is that the dark boxes heat up warming the soil, so my growing season is extended. If you are growing eggplant in regular containers, in the spring, on cool nights it's a good idea to protect them from the cold by either moving them into a warm space (I use my garage) or to cover them up with a cloche or cloth.
Starting Eggplant from Seed - Eggplant are somewhat challenging to grow from seed, but it is worth the effort because of the huge variety you can buy in seed form, while nurseries often only carry a few varieties. Eggplants seeds need warmth to germinate and can't be planted too deeply. Look on your seed packet for planting depth. While you can direct seed eggplant, I start mine eight to ten weeks before the last frost date.
Harvesting Eggplant - Eggplants come in a wide range of sizes, colors and shapes. They can be white, purple, almost black, bright green, and speckled. They can be round, long and thin or pear-shaped. You will need to know what kind of eggplant you have planted to know when to harvest it. A rule of thumb though is to pick eggplant when the skin appears glossy and it the fruit has a little give when you squeeze it. While you don't want to pick eggplant before it is ripe, I generally pick them when they are on the small side.
Staking - It is a good idea to stake your eggplants before they get too large to avoid disturbing the roots once the plant is established. Most varieties will be fine tied to a piece of bamboo or a wooden stake sunk all the way into your pot. You can also build a bamboo cage or I also like to use brightly colored coated metal tomato cages.
Roasting Eggplant - There are about a million ways to cook eggplant, but for freshly picked garden eggplant I prefer to simply roast it. I leave on the skin and cut it into small pieces about a half-inch square. I pre-heat the oven to 400 °F. I toss the eggplant with a little olive oil, a little Kosher salt and pepper. I then lay them in a single layer in a baking pan with sides. I cook, turning once or twice, until the eggplant is brown and soft. I eat them right out of the oven, or also cold the next day.
Pests and Problems - As mentioned above, eggplant is prone to verticillium wilt but if you use potting soil, this probably won't be a problem. Consistent watering is key to eggplant health. Letting the pot dry out too much even once can create problems for the creation of beautiful, unmarred eggplants. If you see tiny round holes in the leaves of the plants early in the season, you could have flea beetles, but again, it isn't as likely if you are using potting soil.
My favorite varieties of eggplant: