LettuceLactuca sativa

Lettuce changes its mind with the months. In spring and autumn, it wants full sun and soil that warms up quickly, against a south wall or under a cold frame. In summer, it prefers partial shade: the foot of climbing beans, the light shade of tomatoes or the east side of a bed spare it from bolting. It slips in everywhere, between cabbages that will grow later, along the edge of leek rows, in a square free for six weeks. Moist soil, rich in humus, without standing water, remains the only real condition.

Lettuce has short roots and grows fast: it needs a very fine, rich and loose surface layer. Fork the soil over to fifteen centimetres, work in two to three kilos of mature compost per square metre, then rake to a surface free of clods. In our clay soils that crust after rain, a surface dressing of leaf mould or potting compost helps germination. Avoid fresh manure, which attracts slugs and gives bland leaves. A bed already well manured for last year's squashes or cabbages will do without adding anything.

Sow a small quantity, two or three metres of row, every three weeks from March to August, rather than a whole bed in one go. The seeds need light: lay them in a drill half a centimetre deep, barely cover with fine compost and firm. They germinate between 10 and 20 °C, but go dormant above 25 °C. In July, therefore, sow in the evening, in the shade, or chit the seeds for two days in the fridge in a damp cloth before sowing. Germination takes four to eight days. Under cover, a February sowing gives plants ready to transplant by the end of March.

Each season has its lettuces. For March-April, choose early butterheads such as Reine de Mai or Merveille des quatre saisons. For summer, prefer batavias, cos and loose-leaf lettuces, such as oak leaf or Lollo, which are slower to bolt; the so-called bolt-resistant varieties are worth their price in July. For autumn, go back to hardy butterheads and batavias. For winter under a cold frame or tunnel, sow winter lettuces in September-October, Val d'Orge, Merveille d'hiver or Brune d'hiver, which will heart up in April. Always mix two or three types to spread the harvests.

Transplant the plants at the four- or five-leaf stage, three to four weeks after sowing, on an overcast day or in the late afternoon. With a trowel, open a hole just big enough, and set the root ball so that the neck, the join between leaves and roots, stays at soil level or slightly above. Buried too deep, the lettuce rots or does not heart up; set too high, it dries out. Space twenty-five centimetres apart for butterheads, thirty for batavias and cos, twenty for loose-leaf types. Water at once with a fine spray, then shade for two days with an upturned crate in summer.

Lettuce is the queen of the balcony. A window box fifteen to twenty centimetres deep, filled with good-quality potting compost with a little garden compost added, takes one lettuce every twenty centimetres or a dense sowing of loose-leaf lettuce to pick leaf by leaf. Place it in the morning sun and in afternoon shade in summer. Water every day in hot weather, as the compost dries out quickly, and every two or three days in spring. A saucer prevents drying out but must not stay full. Slugs climb less readily up to containers, which makes life a great deal easier for the town gardener.

Sowing the whole packet at once produces thirty ripe lettuces in the same week, then nothing: sow in small quantities. Burying the seed two centimetres deep stops germination, as it needs light. Transplanting too deep rots the neck. Letting the seedlings crowd in the seed row without thinning gives drawn lettuces that never heart up. Forgetting the slugs for the first few nights means losing everything. Finally, sowing a spring butterhead in July leads straight to bolting: read the season printed on the packet, it is the most useful piece of advice in this whole guide.

Lettuce is 95 % water: the soil must never dry out deep down. Water in the morning, at the base, two to three times a week in spring and almost every day in a heatwave, without wetting the heart, which would rot. A generous watering, five litres per square metre, is better than small sprinklings that do not soak in. A lettuce short of water toughens, turns bitter and bolts as soon as the heat returns. In autumn and under a cold frame, cut back sharply: excess moisture in cold weather leads to grey mould and downy mildew.

A mulch of two to three centimetres of dried grass clippings, hemp or flax mulch, laid after transplanting, keeps the soil cool, stops soil splashing onto the leaves and limits weeding. Leave a gap around the neck and do not mulch too thickly; slugs love damp mulch. In autumn and spring, it is better not to mulch at all, to let the soil warm up. Lettuce needs no fertiliser in composted soil; a very dilute nettle liquid can wake up a plant that has stalled, but excess nitrogen gives soft leaves that rot.

In a sowing in place, thin as soon as the seedlings have three leaves, first to ten centimetres, then to twenty-five, transplanting the removed plants elsewhere. A crowded lettuce stays small and drawn. Loose-leaf lettuces can be left denser, every ten centimetres. Cos and some batavias heart up better if you tie them loosely with a strand of raffia a week before harvest, which blanches and tenderises the heart. Remove damaged or rotten outer leaves as you go, as they attract slugs and fungi.

Slugs are enemy number one, especially in our wet springs. Transplant sturdy plants rather than sowing in place, go hunting with a head torch for the first few evenings, set traps under planks and surround the plants with ash or eggshells in dry weather. Aphids lodge in the heart of butterheads: hose them off or spray soft soap diluted to 5 %. Against grey mould and downy mildew, give air, water in the morning, do not wet the foliage and remove affected leaves. Fine insect-proof mesh protects against birds and rabbits.

In February-March, sow under cover and transplant under a cold frame the winter lettuces sown in October. In April, transplant outdoors under fleece and start sowing in place. From May to August, sow every three weeks, transplant, water, hunt slugs; in July, switch to summer varieties and partial shade. In September, sow the last autumn butterheads and the winter lettuces. In October, put a tunnel or cold frame over the autumn plants. In November-December, ventilate the frame whenever the weather is mild and dry, and harvest the last batavias.

Cut butterheads at ground level, in the morning, as soon as the heart resists under the hand: three days more and they stretch, turn bitter and bolt. Loose-leaf lettuces are picked leaf by leaf, starting from the outside, or sheared three centimetres above the neck, for two or three regrowths. To extend the season, a fleece in March and October gains three weeks at each end, and a cold frame allows a harvest in November and from April. Let one plant a year go to seed: its seed, gathered in August when the tufts turn white, resows your favourite variety.