Eggplant may be oval shaped or elongated. Oval varieties include ‘Dusky’ and ‘Black Bell’ that ripen in about 60 days, and ‘Black Beauty’ and ‘Burpee Hybrid’ that mature in 70 to 80 days. Elongated varieties of eggplant, such as ‘Slim Jim’ and ‘Little Fingers’, take about 70 days to mature. If you are looking for a unique eggplant, consider going with a pink, white, green or orange-skinned variety. Each year, I try a different variety (always purple) and each variety grows well and tastes great.
As with all vegetables, choose a sunny and well-drained location to plant eggplant. Turn the soil to a depth of at least 12 inches. I like to spread about 2 inches of leaf mold over the area and then work that into the soil as a form of organic fertilizer.
I think that it is easier to plant nursery starter plants than to grow eggplant from seeds, which would require starting the seeds indoors about two months ahead of planting time. Nursery-grown eggplant starters are available in your area at planting time from home and garden centers or plant nurseries. Set the plants in the ground so the top of the root ball is level with the surrounding soil. Set multiple plants 18 to 24 inches apart. I make an opening in the soil for the young plant using a hand trowel that is about 12 inches long. The hand trowel then becomes an easy measuring tool to gauge the distance between plants.
When to pick eggplant from the garden
When to harvest eggplant is sort of like deciding how much to blow up a balloon. Inflate the balloon too much and it can burst; leave the eggplant to grow too long and it can become tough and inedible.
Eggplant is ready to harvest when it reaches a size equal to the area of two adults fists, which could be 4 to 6 inches long. The skin of the eggplant should be shiny. The eggplant can be left to grow longer. Each time I change eggplant varieties, I let one of the first eggplants grow beyond 6 inches. Once the skin of the eggplant starts to lose its glossy finish, I know that it has been on the plant too long. Using the size of that eggplant experiment, I make sure to harvest other eggplants when they are at least 1 inch smaller than the experiment fruit.
How to harvest eggplant
The green cap of eggplant, which called a calyx, is speckled with thorns so avoid grabbing the top of the stem. Instead, hold the eggplant at the bottom and use a knife or pruners to snip the stem about 1 inch from the eggplant.
Source: Watch Your Garden Grown, Eggplant, University of Illinois Extension