Growing eggplant is easy… provided you cater to its specific needs. Its main demand is heat, followed by nutrient-rich, evenly moist soil.
Eggplant seeds need temperatures between 80-90°F to germinate well, so for many of us, that means either starting them indoors on heat mats or waiting until June to plant.
Plant seeds about ¼” deep in 2” soil
blocks, pots or cells, and be careful to never let them dry out. Start
them indoors under lights about 6-8 weeks before your last frost date,
and transplant them out about 2 weeks after last frost, when
the soil has warmed to at least 65°F. They’ll be in their pots about
8-10 weeks total, which is less than some writers recommend.
I’ve learned to resist the urge to start growing eggplant or other starts too early in the spring, and now plant most of my indoor starts later than many people.
On transplant day I’d rather have my seedlings be small and stocky with healthy undisturbed roots, than tall, spindly and root-bound in their containers. Growing eggplant requires patience, because it really doesn't like being transplanted out too early.
Even though eggplant seeds need heat to germinate, transplants can go out when the soil has warmed to about 65°F, and there is absolutely no danger of frost. But if you’re direct seeding outside, wait until the soil in the day is 80°F.
As with any indoor starts, make sure you harden the seedlings off properly before transplanting them out, or they’ll go into shock and can die or be set back for life. Seedlings must have time to physiologically adapt to the intensity of sunlight and wind. Take them outside every day for increasing amounts of time over the course of about 7-10 days. For more details see Starting Seeds Indoors.
Eggplants will turn bitter if the soil is allowed to dry out. I now use T-Tape dripline in my garden, which has emitters every six inches. The parallel driplines are laid out so that the emitters on adjacent lines are staggered, or offset from one another, for maximum coverage. I spaced the lines eight inches apart, which is fine for established plants, but when my seedlings first go in, I also water by hand until their root systems are big enough to reach the nearest emitter. I mulch about 2” deep with duck-manured straw. (It's very dry where I live in Colorado, and water is expensive. It's a dance between expense and giving the plants enough).
Sometimes you’ll read that a crop prefers a certain pH of soil. That's not really useful information for a couple of reasons: 1) if your soil’s calcium, magnesium and other cation nutrients are in the right proportions, the pH will take care of itself, and 2) changing pH alone will not solve the underlying problems that are causing the pH to be out of whack (these two things are really the same). The solution to too high or low pH is balancing your soil minerals, covered in the article Organic Fertilizer.
When I was a kid I always wondered why it was called “eggplant”, since I’d never seen a purple egg. Then one day I was leafing through the Baker Creek Heirloom Seed catalog, and there it was: a Japanese white eggplant that looked exactly like an egg!
The eggplant is native to India, but from there it has spread through the cuisines of the world. It has been bred in a huge variety of shapes and colors, including round, long and skinny, stout and fat; yellow, orange, red, green, dark and light purple and striped. Baker Creek Heirloom Seeds has a beautiful selection of varieties suited to many purposes and climates.
The most common thing “bugging” eggplants is flea beetles: tiny, shiny, ground-dwelling beetles that chew pinholes all over eggplant leaves, especially on young plants. I’ve found that good ol’ fish emulsion fertilizer, mixed up at ½ Tbsp per half gallon and sprayed on the leaves every couple of days, repels them. I don’t know if they don’t like the taste of it, or if it just smells so bad they can’t find the eggplant, but it works.
Colorado potato beetles also like eggplant. They and their larva are big enough to squish, so if you only have a few eggplants, I recommend just keeping watch and squishing any you find. Neem oil spray will also work, but it’s not an immediate “cure”. It disorients the beetles, interrupting their reproductive cycle. And then there is diatomaceous earth, which works on many kinds of hard-bodied insects. Check out the controlling garden pests page for more details.
Many eggplant varieties are susceptible to Verticillium wilt, for which there is no organic cure. Prevent it by not letting the soil stay wet (just moist, but never soggy), by optimizing the plants' overall health by supplying the right amount of good compost and sufficient mineral nutrition, and by rotating crops. Eggplant is in the same family (Solanacea) as tomatoes, peppers and potatoes, so don’t plant any of those crops in the same spot more than every few years.
Harvest when the growing eggplant has reached full size (has stopped getting larger) but before it is fully mature, or the seeds will be large, tough and annoying when trying to eat it. The skins should be very shiny, and if you press it with your thumb it should be slightly spongy, but bounce back after a light squeeze.
Clip them off just above the calyx (the green part that's like "fingers" holding the eggplant) with pruners, and be careful not to stab yourself on the spines that sometimes form at the pointy tips of the calyx.