How to Grow a Japanese Eggplant

Garden bed

A garden bed gives the roots more room to chase moisture and produces taller bushier plants. The slim fruit yields are heaviest from in-ground plants in long warm summers. Pick a bed that gets at least 8 hours of direct sun and has been amended with two to three inches of compost.

Crop rotation matters here. Do not plant Japanese Eggplant where any nightshade family member grew in the previous two years, since soil-borne wilts persist for that long.

Pot

A 5-gallon or larger container suits one plant for the season. Black or dark containers warm faster than light ones and produce earlier fruit in cool-summer regions. The container must drain freely from the bottom.

Container plants need water and feeding more often than in-ground ones. Plan to water daily in July heat and feed weekly with a half-strength liquid fertilizer.

Sun

Eight or more hours of direct sun produces the heaviest crop. Six hours is the practical minimum and yields a lighter harvest with smaller fruit.

A south-facing exposure with reflected warmth from a wall or paved patio adds heat that speeds fruit set in cooler regions.

Drainage

Well-drained soil is essential. The roots rot quickly in soggy conditions. Raised beds and large containers both excel here, since drainage is built in. Heavy clay yards benefit from a raised mound or extensive amendment with coarse compost.

Soil

Rich loamy soil with plenty of organic matter is what the plant wants. Work two to three inches of compost into the planting area before setting out the transplants. Slightly acidic soil is ideal.

Crop rotation

Do not plant Japanese Eggplant where any nightshade crop grew in the previous two years. Verticillium and Fusarium wilts persist in the soil and reduce vigor across the family. The clean rotation runs nightshades, then legumes, then leafy greens, then root crops over four years.

Watering

Water deeply twice a week through the growing season, soaking the root zone rather than splashing the foliage. Drip irrigation or a slow hose at the base prevents fungal leaf diseases.

Containers dry fast in summer heat and may need water daily in July. Consistent moisture during fruit set prevents the misshapen fruit and blossom-end rot that follow swings between dry and wet. Mulch helps even out soil moisture.

Feeding

Start with a balanced fertilizer every two weeks until the first flowers appear. Once flowers open, switch to a low-nitrogen vegetable fertilizer or one labeled for tomato. Too much nitrogen produces lush leaves at the expense of fruit.

Container plants need a half-strength liquid feed weekly to keep up with the limited soil volume. Yellow leaves between green veins call for a magnesium boost with a teaspoon of Epsom salt dissolved in a gallon of water and watered in around the base.

Staking and tying

Tie the main stem to the stake loosely with soft twine or a strip of cloth, adding new ties every 8 to 10 inches as the plant grows. The slender fruit weighs down the side branches and the plant tips without support. A small tomato cage works in place of a stake.

Lower leaf removal

Remove the lowest few leaves once the plant is a foot tall and the main stem has thickened. Lower leaves often touch the soil and pick up fungal spores. The opening improves airflow and reduces leaf-spot pressure.

Pinching the first flowers

Pinch off the very first one or two flowers that appear before the plant is at least 18 inches tall. The early flower drains the plant before it has the size to support fruit. After that, leave all flowers in place and the plant settles into its summer rhythm.

When it's ready

Pick the fruit at 6 to 10 inches long while the skin still shines and the flesh feels firm with light give when pressed. Dull skin and a softer feel signal an over-ripe fruit that has turned seedy and bitter.

The fruit can be picked smaller than 6 inches if the plant is loaded and you want to encourage more set. Smaller fruit is more tender but yields less per plant overall.

Picking and storing

Cut the stem with hand pruners about half an inch above the fruit. Pulling the fruit off tears the calyx and shortens storage life. The calyx and stem can be lightly prickly, so wear gloves if the variety is thorny.

Stored at cool room temperature, fresh fruit keeps for three to five days. Refrigeration extends that to a week but cold below 50 F causes pitting on the skin, so the crisper drawer is the right spot if storing cool.

End of season

Pinch off any newly forming flowers six weeks before the first expected frost so the plant puts its energy into ripening existing fruit. Harvest all reachable fruit before the first hard frost, since cold-damaged fruit turns mushy fast.

No fruit despite flowers

Nighttime temperatures below 60 F or above 90 F prevent pollination. Once nights settle into the 65 to 80 F range, fruit sets reliably. A daily gentle tap on the stem during open-flower hours improves self-pollination in still-air gardens.

Tiny holes all over young leaves

Flea beetles, the family's signature pest. The tiny black or bronze beetles jump when disturbed and skeletonize new foliage. Cover young transplants with floating row cover until the plant is large enough to outgrow damage. A neem or spinosad spray helps heavy infestations but timing matters since the beetles hop fast.

Yellowing wilting plant

Verticillium or Fusarium wilt, soil-borne fungal diseases common in poorly rotated nightshade beds. Yellowing starts on one side of the plant and progresses upward. Once present, no spray helps. Pull infected plants and grow in a different bed for at least three years.

Brown spots with concentric rings on leaves

Early blight or a related fungal leaf spot, especially after a wet week. Remove infected leaves and discard. Improve airflow by removing lower leaves and avoid overhead watering. A copper fungicide every 7 to 10 days during humid weather helps in severe cases.

Curling distorted new growth

Aphids on the underside of new leaves, or thrips feeding inside the buds. Knock aphids off with a strong water spray and follow with insecticidal soap if needed. Thrips are harder to spot and respond to a spinosad spray on the new growth flush.

Black sunken end on the fruit

Blossom-end rot from uneven watering and calcium uptake issues. The fruit cannot draw calcium when soil moisture swings. Mulch the root zone two inches deep and water on a regular schedule. The next round of fruit usually comes in clean.

Spider mites on leaves

Fine pale stippling on the upper leaf surface from tiny mites on the underside. Hot dry weather brings them on fast. Shower the plant with a strong water spray every few days. Insecticidal soap helps heavy infestations. Misting around the plant raises local humidity and slows mite reproduction.

Whitefly clouds when leaves are brushed

Tiny white insects rise off the plant in a cloud when disturbed. The young larvae feed on the underside of leaves. Yellow sticky traps catch adults. Knock larvae off with a strong water spray every few days. Heavy infestations respond to insecticidal soap.

Misshapen pale fruit

Inconsistent watering or low temperatures during fruit development. The first fruit of the season often looks rough, with later fruit coming in more shapely as the weather warms and the plant settles in. Mulch the root zone and maintain steady moisture to even out development.

Hornworms stripping leaves overnight

Large green caterpillars with horns on the tail end strip leaves and chew on fruit. Hand-pick at dawn or dusk when they are most visible. A Bt spray applied while caterpillars are small kills them within a few days. Wasp larvae on the back of a hornworm are a good sign and call for leaving that hornworm alone.