Eggplant

Start seed indoors 8 to 10 weeks before you can plant out

Sow indoors 8 to 10 weeks before your intended outdoor planting date, which is itself well after your last frost. Use containers of at least 2 inches so the roots are not cramped, and water in with a phosphorus starter solution when you finally set the plants out. Eggplant needs 65 to 90 days from transplanting to first harvest, so direct sowing wastes the warm weeks it actually needs. Bigger cells mean less transplant shock, and eggplant checked by shock is slow to recover.

Plant out only once nights stay above 50F

Wait until nighttime lows are consistently above 50F and the soil has warmed before setting plants out. Space plants 18 inches apart in rows 30 to 36 inches apart. Choose ground that has not grown eggplant, tomato, pepper or potato for 4 to 5 years. Eggplant is more cold-sensitive than tomato and simply stops growing in cold soil; set out too early it may never recover and bear fruit, so an early planting gains nothing and often costs vigor. The rotation matters because Verticillium wilt survives as microsclerotia in soil for up to 10 years and there is no way to cure an infected plant (NC State, Verticillium Wilt of Tomato and Eggplant).

Black plastic mulch to drive soil heat

Lay black plastic mulch over the bed once the soil has begun to warm, and plant through it. Do not lay it over cold soil. Black plastic traps heat in the root zone, and eggplant growth is governed by soil warmth more than by the calendar. It also keeps soil from splashing onto the lower leaves.

Sidedress nitrogen at first flowering

When the first flowers open, sidedress nitrogen at roughly 40 to 60 pounds per acre, scaled to your bed. If you are on drip, feed about 10 pounds per acre per week for four weeks starting a week after transplanting instead. Skip the sidedress if the bed is under plastic mulch. First flower is when the plant switches from building leaves to filling fruit and its nitrogen draw jumps. Feeding earlier or heavier just makes a bushy plant that delays fruiting, which is why excess nitrogen is the classic eggplant mistake.

⚠ Do not use combination Weed and Feed products on a vegetable bed.

Count flea beetles every few days for the first month

Check young plants every few days for the first month after planting, looking for shot-hole feeding. Treat newly set transplants at 2 beetles per plant, plants 3 to 6 inches tall at more than 4 beetles per plant, and plants over 6 inches at 8 beetles per plant. Eggplant seedlings establish slowly and can be turned to lace with little chance of recovery, while a plant past 6 inches shrugs off the same feeding. The threshold rises with plant size because the plant's ability to outgrow the damage rises with it.

Spinosad for flea beetles on young plants, before flowering starts

If scouting puts you over threshold while the plants are still small and have not begun to flower, spray spinosad. Handpick instead once plants are large and flowering, since Colorado potato beetle and flea beetle adults are both easy to pick off by hand in a garden. Flea beetle feeding is only economically serious in the first weeks, so the one spray that pays for itself lands well before the first flower opens. Spinosad also controls Colorado potato beetle, which arrives in the same window.

⚠ Spinosad is toxic to bees and must not be applied to a blooming crop. Pre-harvest interval is 1 day on eggplant. Rotate active ingredients rather than repeating one, because Colorado potato beetle develops insecticide resistance rapidly.

Row cover on hoops the day you transplant

Place floating row cover over hoops immediately after transplanting and seal the edges to the soil all the way around. Hoops are required here because the cover cannot rest directly on eggplant foliage. Flea beetle adults overwinter in leaf litter at field edges and walk or fly in within days of planting. A cover sealed before they arrive excludes them entirely during the window when the plant cannot afford any leaf loss, and it costs nothing in pollination because eggplant flowers set fruit on their own.

Cut while the skin is still glossy

Begin picking 65 to 90 days after transplanting, when the fruit has reached size and the surface is glossy and the flesh still firm. Clip the fruit with shears leaving about a 1 inch stem. A dull or bronzed skin means you waited too long. Gloss is the visible signal that the seeds have not yet browned and hardened. Once the skin goes dull the seed coats have set and the flesh turns bitter and spongy, and leaving overmature fruit on the plant also shuts down further fruit set.