Skip to content
Grow In Backyard
Vegetables

How to Grow Eggplant: Heat, Flea Beetles and Fruit Set

Eggplant needs more heat than tomatoes and takes the worst of the flea beetles. Soil temperature, spacing, why flowers drop, and picking by shine.

By Zakaria 5 min read Save to Pinterest — opens Pinterest in a new tab
A single glossy purple eggplant hanging from the plant below its spiny green calyx
Photo: Azreey, CC BY-SA 4.0, via Wikimedia Commons
On this page

Eggplant wants more heat than a tomato and takes the worst of the flea beetles. Get those two right and the rest of it is straightforward.

Timing, which most people get wrong

Warmth needed, against its relatives
CropMin soil tempPlant out
Tomato60°FAt last frost
Pepper65°F1–2 weeks after
Eggplant65–70°F2–3 weeks after

A transplant set into cold soil does not catch up. It sits, sulks, drops leaves, and is overtaken by one planted a fortnight later into warm ground. Use a soil thermometer rather than the calendar.

Starting seed:

  1. 8 to 10 weeks before your planting-out date
  2. A heat mat is close to essential — germination wants 80–90°F and is slow and patchy below
  3. Sow ¼ inch deep; expect 7 to 14 days
  4. Pot on once true leaves appear
  5. Harden off over a week to ten days
  6. Plant out only when nights are reliably above 60°F

Site and soil

Conditions
Sun6 hours minimum, 8 better. Not negotiable
SoilRich, well drained, pH 5.5–6.8
Spacing18–24 in apart, rows 30 in
Containers5 gallons per plant. Pots warm faster, which suits it
WaterDeep and consistent — 1 to 1.5 in a week
FeedBalanced at planting; easy on nitrogen once flowering
SupportStake or cage. Fruiting plants split in wind
MulchYes, once the soil is properly warm — not before

Black plastic or dark mulch laid a couple of weeks before planting warms the soil measurably and is worth doing in a cool-summer region. Organic mulch does the opposite early on, so hold it back until the ground is warm.

Flea beetles

The one pest that genuinely decides the crop.

Cover from the day they go out, not after damage appears

Eggplant is the nightshade flea beetles hit hardest, and a young transplant with four leaves can be checked so badly it never recovers. By the time you see the shotholes, the damage is done.

Floating row cover or insect mesh, sealed at the edges, from planting day. Leave it on three to four weeks, then remove it so the flowers can be worked by air movement and insects.

Kaolin clay — a white film they dislike landing on — works unusually well on eggplant and is the best follow-up once the cover comes off.

A mature plant carries a remarkable amount of shothole damage with no loss of yield. The effort belongs in the first month and nowhere else.

Fruit set

Eggplant flowers are self-pollinating, so a plant that flowers and sets nothing has an environmental problem, not a bee problem.

Why blossoms drop
CauseFix
Nights below 60°FWait. Row cover for warmth early in the season
Days above 95°FShade cloth, steady water. Set resumes when it cools
Drought stressDeep, consistent watering; mulch
Too much nitrogenSwitch to a lower-nitrogen feed
Still, humid airShake the plant gently each morning

Most blossom drop is temperature, and temperature is not a gardening failure. Plants resume setting when the weather turns.

Harvesting

By shine, not by size. Varieties differ enormously in mature size, and the packet number is a poor guide.

  • Glossy, taut skin — ready
  • Press gently with a thumb: it should spring back slowly
  • Dull skin means past it. The flesh is spongy and the seeds have hardened and gone bitter — that is over-ripe, not riper
  • Cut with secateurs, leaving an inch of stem. The calyx is spiny and the stem too tough to pull without tearing the plant
  • Pick often. Every fruit left on slows further flowering

Bitterness is usually harvest timing, not the variety

Modern varieties are bred to be mild, and the salting ritual is largely a holdover. A bitter eggplant is nearly always one picked after the skin dulled and the seeds hardened.

Pick young and glossy and you can skip the salting entirely.

Problems

  • Shotholes in the leaves — flea beetles. See above
  • Sunken dark patch at the blossom end — blossom end rot. Irregular watering blocking calcium uptake, not a soil shortage. Water consistently and mulch
  • Wilting on one side, yellowing lower leaves — verticillium wilt. No cure; rotate away from nightshades for several years and choose resistant varieties
  • Fine webbing and stippled leaves — spider mites, worst in hot dry spells. Spray the undersides with water
  • Soft brown fruit rot after wet weather — phomopsis blight. Airflow, rotation, remove affected fruit
  • Clouds of tiny white flies — whitefly, mostly cosmetic outdoors

Varieties worth knowing

  • ‘Black Beauty’ — the classic large Italian type. Needs a long warm season
  • ‘Ichiban’, ‘Little Fingers’ — slender Asian types, earlier and more productive in a short season. The better choice in a cool summer
  • ‘Rosa Bianca’ — pale lavender-white, mild and creamy
  • ‘Fairy Tale’ — small striped fruit on a compact plant. Excellent in containers
  • ‘Listada de Gandia’ — purple and white striped, heat-tolerant

In a cool or short summer, the slender Asian types are the ones that actually crop. A large Italian variety in a marginal climate flowers beautifully and ripens two fruits.

Common questions

When should I plant eggplant?

Later than you think. Eggplant wants soil at 65 to 70°F and nights consistently above 60°F, which is usually two to three weeks after the last frost — later than tomatoes and peppers go out. Start seed indoors 8 to 10 weeks before that date, on a heat mat, because germination needs 80 to 90°F and is slow and patchy below it. A transplant set into cold soil sulks for weeks and is often overtaken by one planted a fortnight later.

Why are my eggplant flowers falling off without setting fruit?

Temperature is the usual reason. Eggplant drops blossoms when nights fall below about 60°F or when days run above 95°F, because pollen becomes unviable at both extremes. Other causes are drought stress, too much nitrogen driving leafy growth at the expense of fruit, and dense still air preventing the self-pollinating flowers from shedding pollen. Shade cloth in a heat wave, steady watering and a gentle daily shake of the plant address most cases.

How do I stop flea beetles destroying my eggplant?

Cover the plants with floating row cover or insect mesh from the day they go out, sealed at the edges, and leave it on for three to four weeks until the plants are robust. Eggplant is the nightshade flea beetles hit hardest, and a small transplant can be checked so badly it never recovers. Kaolin clay sprayed as a white film also works well on eggplant specifically. Mature plants tolerate a great deal of shothole damage without losing yield, so the effort belongs in the first month only.

How do you know when eggplant is ready to pick?

By shine and by touch rather than size. A ready fruit has glossy, taut skin and springs back slowly when pressed gently with a thumb. Once the skin dulls, the flesh has gone spongy and the seeds have hardened and turned bitter — that is past its best, not riper. Cut with secateurs leaving an inch of stem, since the calyx is spiny and the stem is too tough to pull without damaging the plant. Pick often, because every fruit left on slows further flowering.

How much space do eggplants need?

Eighteen to 24 inches apart, in rows about 30 inches apart, and a 5 gallon container per plant if growing in pots. They also need staking or caging — a plant carrying several mature fruits is top-heavy and splits at the crotch in wind. Full sun, at least six hours and preferably eight, is not negotiable. In containers they do genuinely well, and the soil warms faster in a pot, which suits a crop this heat-hungry.

What are the black or brown patches on my eggplant fruit?

A sunken, leathery, dark patch at the blossom end is blossom end rot, caused by calcium not reaching the developing fruit — almost always a watering problem rather than a soil shortage, since irregular moisture is what blocks calcium uptake. Water deeply and consistently, mulch to even out soil moisture, and avoid heavy nitrogen feeding. Soft brown rot elsewhere on the fruit, particularly after wet weather, is more likely to be phomopsis blight, which needs airflow, rotation and the removal of affected fruit.

Backyard Weekly

Know what to plant, week by week

Join the weekly email for seasonal jobs, fixes for what is going wrong, and gear worth buying.

Not ready to subscribe? The planting calendar is free and needs no email.

By subscribing you agree to our privacy policy. Grow In Backyard will never sell your address.

Keep reading