AubergineSolanum melongena

The aubergine is the most cold-sensitive of the nightshades: it only really grows above 18 °C and its flowers drop below 15 °C at night. In Belgium, a greenhouse or polytunnel is almost essential for a harvest worthy of the name; the credible alternative is a large black pot against a south-facing wall, in a corner closed to wind. Put it in the warmest spot you have, even if it means sacrificing a tomato. Avoid proximity to potatoes, whose Colorado beetles adore its foliage, and the spot where last year's nightshades grew.

The aubergine demands rich, light and above all warm soil. Loosen deeply, work in three to four kilos of mature compost per square metre and a handful of ash, then form a twenty-centimetre mound lightened with sand in clay soils. Cover the bed with black film or a dark mulch three weeks before planting to store heat; in a greenhouse, this precaution alone gains ten days. Avoid fresh manure and nitrogen fertiliser, which give a magnificent plant without fruit. Soil that stays sodden is a deal-breaker: the roots rot and the plant wilts beyond recovery.

Sow from mid-February to early March: any later and the season is not long enough. Germination needs 25 to 28 °C, on a radiator, a heat mat or on top of a fridge, and takes two to three weeks. As soon as the seedlings are up, give them maximum light, ideally under a grow lamp, otherwise they become leggy. Choose early varieties with elongated or small fruit, more productive in our climate than the classic large purple ones. Without warmth or light in February, buy two or three grafted plants from a garden centre in May: they cost more but are noticeably more vigorous.

Plant out a twenty-centimetre plant with a sturdy stem, hardened off for a good week, in a greenhouse from 20 May and outdoors only in early June, when the nights no longer drop below 12 °C. Space at fifty centimetres, plant at neck level without burying the stem, and water with tepid water. Drive in the stake before setting the plant, as it becomes heavy and brittle. A cloche, fleece or cut-off bottle for the first ten nights avoids a check. Shelter from wind: a single gust tears the broad leaves and costs weeks of growth.

On a warm terrace, an aubergine in a pot often does better than in open ground, because the compost warms up quickly. Allow fifteen to twenty litres per plant, a dark pot, a rich compost with a quarter of garden compost added and a drainage layer. Place it against a south-facing wall, bring it under cover or cover it during June cold snaps. Water regularly without leaving water in the saucer, and feed with a liquid tomato feed every ten days from flowering. Dwarf or mini-fruited varieties give a dozen fruits in a pot, which is very respectable.

Planting outdoors in mid-May, like tomatoes, and watching the plant stand still until July. Sowing in April, too late to harvest before the frosts. Watering with cold water, which chills the root ball and makes the flowers drop. Letting ten fruits form on an outdoor plant: none of them finishes swelling. Forgetting to check for Colorado beetles, which strip a plant in three days. Picking too late, when the fruit is dull, swollen with seeds and bitter. Worrying about the small spines on the calyx: they are normal, just keep gloves on for harvesting.

The aubergine fears thirst as much as excess. Water at the base with tepid water, two to three litres per plant, twice a week in open ground, more often in pots and in full heat, letting the surface dry slightly between waterings. Constantly sodden soil causes wilting and yellowing; water stress drops the flowers and hardens the flesh of the fruit. Water in the morning, never on the foliage. In a greenhouse, mist the soil and paths in hot spells to keep the air humid, which limits red spider mite and helps the flowers set.

Wait until the soil is really warm, mid-June, before laying a mulch, preferably a dark one: leaf mould, miscanthus mulch or dried grass clippings, five centimetres deep. A black film left in place under the plants serves as mulch in a greenhouse. The aubergine is hungry over the long term: comfrey liquid diluted to 10 % every fortnight from flowering, or an organic tomato feed. Add a ring of compost in July. A plant whose leaves pale in midsummer is more often short of food than water. Purplish leaves signal soil that is too cold, not a deficiency.

Pinch out the tip when the plant reaches thirty centimetres; it then branches into three or four main stems, which you tie to the stake with soft ties. Remove the shoots and leaves that appear below the first fork. In a greenhouse, keep two or three stems and cut back the side shoots above the second leaf after a flower. Limit the load: five or six fruits per plant outdoors, eight to ten in a greenhouse, removing surplus flowers from mid-August. Regularly remove yellowed lower leaves and faded flowers, which attract grey mould.

The Colorado beetle prefers aubergine to potato: inspect the undersides of the leaves twice a week from June, crush the clusters of orange eggs and collect larvae and adults into a bucket of soapy water. Keep the crop away from any row of potatoes. In a greenhouse, red spider mites turn the leaves grey and then dry in hot, dry weather: mist every morning, ventilate and spray the undersides of the leaves with soft soap. Aphids are treated the same way. A plant that wilts suddenly in midsummer is suffering from excess water or verticillium wilt in the soil, hence the strict four-year rotation.

Mid-February: sowing on bottom heat. March: pricking out into pots under a lamp or on a south-facing window. April: plants in full growth, maximum light, first diluted feed. Mid-May: hardening off and planting in the greenhouse with a stake. Early June: planting outdoors, cloche on cool nights, pinching out at thirty centimetres. Late June: mulching, first comfrey feed, weekly check for Colorado beetles. July: flowering, regular watering with tepid water, misting, ties on the branches. August: first fruit, limiting the load, removal of late flowers. September: main harvest. October: last picking, pulling up and noting the rotation on the garden plan.

Pick with secateurs, gloves on, when the fruit is well coloured, glossy and firm, with a slight give under the finger. Skin turning dull and seeds browning signal an overripe, bitter fruit. Picking young, at half size, triggers more flowering and increases the total harvest. In September, close the greenhouse in the evening and lay fleece over outdoor plants to gain two or three weeks. Before the first frost, harvest everything that remains, however small: mini aubergines grilled whole are a treat, whereas a frosted fruit becomes inedible overnight.