Fertilising guide

How to fertilise Eggplant / aubergine (Solanum melongena)— schedule & NPK

Also called aubergine, brinjal, melongene.

About Eggplant / aubergine

Solanum melongena · also called aubergine, brinjal · edible

Eggplant (US) or aubergine (UK) is a warm-season Solanum grown for glossy fruit in purple, white, or striped. Needs heat — fruit set drops below 21°C. Start indoors early and grow in a greenhouse or sunny sheltered spot in cool climates. Foliage is toxic to pets.

Solanum melongena was domesticated in tropical Asia (India/Bangladesh and the surrounding region) from the wild S. insanum; it is a tender, frost-intolerant warm-season perennial grown as an annual.

Moderately heavy feeder — incorporate compost plus balanced fertilizer at planting and side-dress as fruit begin to set; excess nitrogen produces foliage at the expense of fruit.

Growth habit: Bushy upright annual

Watch for — Pale undersized fruit: Under-feeding or root-bound in containers.

Sources: extension.umn.edu, hgic.clemson.edu, frontiersin.org

What fertiliser eggplant / aubergine actually wants — and why

Eggplant / aubergine feeds in two distinct phases — balanced to build the plant, then high-potassium the moment flowering starts to set and fill a heavy crop.

For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for eggplant / aubergine: match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.

How often to feed eggplant / aubergine, and which months

Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For eggplant / aubergine:

Balanced feed at planting; high-potash feed once flowering. So: a balanced feed or compost at planting, then a high-potash liquid every 1-2 weeks from first flower through harvest across the main season (spring through early autumn).

The dormant-season rule matters more than the exact interval: skip feeding entirely when eggplant / aubergine is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.

What strength to mix for eggplant / aubergine

Follow the crop-feed label rate for eggplant / aubergine — these are calibrated for hungry vegetables. Consistency through fruiting matters more than strength; erratic feeding causes problems like blossom-end rot.

Feeding always goes onto already-damp soil, never dry roots — water eggplant / aubergine first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the eggplant / aubergine watering schedule.

Signs you are over-feeding eggplant / aubergine

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for eggplant / aubergine:

Vigorous dark-green leafy growth but few flowers or fruit (excess nitrogen).
Lush foliage hiding the crop; soft growth prone to pests and disease.
Salt crust on the soil and scorched leaf edges in containers.

Signs you are under-feeding eggplant / aubergine

Pale, yellowing lower leaves and stunted growth.
Small fruit, poor set, and a quickly exhausted plant.
Blossom-end rot and weak cropping from erratic or insufficient feeding.

If the symptoms point at watering, light or roots rather than nutrition, the full eggplant / aubergine care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

In containers, fertiliser salts build up fast — water eggplant / aubergine thoroughly so excess drains from the base each time, and flush pots with plain water every few weeks to prevent a damaging salt build-up.

Organic vs synthetic feeds for eggplant / aubergine

Organic options

Garden compost or well-rotted manure dug in before planting, plus a liquid comfrey or seaweed feed once fruiting starts. UK: comfrey feed or organic Tomorite; US: Espoma Tomato-tone or Neptune's Harvest. Builds soil and feeds in one.

Synthetic / liquid feeds

A balanced feed at planting then a high-potash tomato feed in fruiting — UK: Growmore at planting then Tomorite (Levington) or Phostrogen; US: a balanced 10-10-10 then Miracle-Gro Tomato or a bloom booster.

Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.

Fertilising eggplant / aubergine — frequently asked questions

What fertiliser does eggplant / aubergine need?

Balanced (even N-P-K) at planting for roots and frame, then switch to a high-potassium ("high-potash") tomato-style feed once the first flowers open — potassium is what sizes and ripens fruit, not nitrogen. Eggplant / aubergine feeds in two distinct phases — balanced to build the plant, then high-potassium the moment flowering starts to set and fill a heavy crop.

How often should I feed eggplant / aubergine?

Balanced feed at planting; high-potash feed once flowering. Balanced feed at planting; high-potash feed once flowering. So: a balanced feed or compost at planting, then a high-potash liquid every 1-2 weeks from first flower through harvest across the main season (spring through early autumn).

What strength of feed for eggplant / aubergine?

What does over-feeding eggplant / aubergine look like?

Vigorous dark-green leafy growth but few flowers or fruit (excess nitrogen). Lush foliage hiding the crop; soft growth prone to pests and disease. Salt crust on the soil and scorched leaf edges in containers. Staying on a high-nitrogen feed once eggplant / aubergine starts flowering is the classic error — you get a huge leafy plant and a disappointing crop. Switch to high-potash the moment flowers appear.

Should I flush the soil of eggplant / aubergine?