On the average plot its cultivation is simple – a row or two in spring and again in early summer, thinning when the seedlings are obviously overcrowded and cutting when the heads are mature. Unfortunately, treating our favourite salad crop so casually often leads to disappointment. Pests and diseases take their toll and the survivors all mature at the same time – the gap between peak condition and starting to run to seed in only a week. Buy a packet of mixed seed containing varieties which mature at different times in order to avoid a sudden glut, or preferably sow seed in very short rows at fortnightly intervals to ensure a regular succession. Another cause of disappointment is bolting before maturity – the usual cause is transplanting at the wrong time or in the wrong way but there are other causes. Finally, even with well-formed heads there is a risk of the leaves being tough and leathery – the usual reason is failure to grow the crop quickly enough. You must ensure adequate humus and moisture in the soil. So lettuces are not quite as easy as some books claim, but if you pick the right varieties, follow the instructions and invest in a few cloches you can enjoy them fresh from the garden nearly all year round.

Types
Cos; Cabbage: Butterhead; Cabbage: Crisphead; Loose-leaf.

Seed facts
Expected germination time: 6-12 days
Approximate number per ounce: 20,000
Expected yield from a 10ft row: 10-20 heads
Life expectancy of stored seed: 3 years.
Approximate time between sowing and cutting: 8-14 weeks (Cabbage and Cos varieties); 6-8 weeks (Loose-leaf varieties)
Ease of cultivation: Not difficult if you sow properly and water regularly. Spring lettuce is not easy.

Soil facts
· Three basic needs have to be satisfied to obtain good lettuces. The soil must contain adequate organic matter, it must not be acid and it must be kept moist throughout the life of the crop.
· For summer lettuce choose a sunny or lightly shaded site. Dig the soil and incorporate compost in autumn or early winter. Shortly before sowing time rake the surface to produce a fine tilth and apply a general fertilizer. Apply Bromophos if soil pests have been a problem in the past.
· Spring lettuce can be grown in a sunny spot outdoors in mild areas without glass protection, but it will not succeed in poorly drained or exposed sites.

Seed sowing
· Sow very thinly ½ in (1cm) deep in rows that are 12in (30in) apart. Cover with soil.
· To grow lettuce for transplanting, sow 2 seeds in a small peat pot. Remove weaker seedling after germination – harden off before transplanting.

Calendar
For a Summer/Autumn Crop:
Sow outdoors in late March-late July for cutting in June-October. For an earlier crop (mid May – early June) sow under glass in early February and plant out in early March under cloches.

For an Early Winter Crop:
Sow a mildew-resistant variety such as Avondefiance or Avoncrisp outdoors in early August. Cover with cloches in late September – close ends with panes of glass. The crop well be ready for cutting in November or December.

For a Midwinter Crop:
Heated glass (minimum 45°F (7°C) in winter) is necessary. Sow seed under glass in September or October – plant out as soon as the seedlings are large enough to handle. The lettuce will be ready for cutting in January-early March. Grow a forcing variety such as Kloek or Dandie.

For a Spring Crop:
If you live in a mild part of the country, sow a winter-hardy variety such as Valdor or Winter Density outdoors in late August-early September. Thin to 3in (7cm) apart in October – complete thinnings to 12in (30cm) spacing in early spring. The crop will be ready in May. For less favoured areas sow in mid October under cloches – harvest in April. Use a winter-hardy or a forcing variety.

Looking after the crop
· Thin the seedlings as soon as the first true leaves appear – avoid overcrowding at all costs. Water the day before thinning. Continue thinning at intervals until the plants are 12in (30cm) apart (9in (23cm) ‘Tom Thumb’ and ‘Little Gem’, 6in (15cm) ‘Salad Bowl’).
· You can try transplanting thinnings in spring or you can plant shop-bought seedlings – do not bury the lower leaves. Lettuces hate to be moved – sow seed whenever you can where the crop is to grow and mature.
· Put down slug Pellets and protect seedlings from birds. Hoe regularly. Keep unprotected plants watered, but the soil under glass should be kept on the dry side. Ventilate glass-grown lettuce whenever possible.
· Always water in the morning or midday – watering in the evening will increase the chance of disease.
· Greenfly can render the crop unusable – spray with Crop Saver. If grey mould strikes, treat with carbendazim or Hexyl.

Harvesting
· Lettuce is ready for cutting as soon as a firm heart has formed. Test by pressing the top of the plant gently with the back of the hand – squeezing the heart will damage the tissues.
· If left after this stage the heart will begin to grow upwards, a sign that it is getting ready to bolt. You must then cut immediately for kitchen use or throw it away.
· It is traditional to cut in the morning when the heads have dew on them. Pull up the whole plant and cut off the root and lower leaves. Put the unwanted plant material on the compost heap.

Varieties
Cos varieties
The cos or romaine lettuce is easy to recognise by its upright growth habit and oblong head. The leaves are crisp and the flavour is good. They are generally a little more difficult to grow than the cabbage types and take longer to mature.
Lobjoit’s Green: One of the old favourite – a large, self-folding variety. Deep green and very crisp.
Paris White: Like Lobjoit’s Green, this variety is popular, large, self-folding and crisp. The heart, however, is pale green.
Little Gem: A quick-maturing cos lettuce which is somewhat cabbage-like in appearance. Sow early for a May or June crop – tie the heads loosely with wool. Many experts consider it to be the sweetest lettuce. The heads are small and compact.
Barcarolle: The beauty of the group – pick this one if you are an exhibitor. Deep green, tightly folded, tall and weighing up to 1lb (500g).
Winter Density: This variety challenges Little Gem for the sweetest lettuce title, but its growing season is different. Sow in August or September for an April crop.
THE LEAF LETTUCE TECHNIQUE
This technique is designed to provide the maximum crop in the shortest time – try it if space is limited. Use a cos variety and sow seeds at 1in (2.5cm) intervals in rows 4in (10cm) apart. Begin in April and make fortnightly sowings until the end of May. Do not thin – this technique produces a block of tightly packed lettuces. Make the first cut 4-6 weeks after sowing – leaves the stumps in the ground to produce a second crop about 6 weeks later.

Butterhead varieties
The butterheads are still the most popular lettuce group. They are quick-maturing and will generally tolerate poorer conditions than the other type. The leaves are soft and smooth-edged – most are summer varieties but a few are hardy lettuces which are used to produce a spring crop and several others are forcing varieties for growing under glass.
All the Year Round: Very popular because it is suitable for spring, summer and autumn sowing. Medium-sized, pale green and slow to bolt in dry weather.
Tom Thumb: The favourite for small plots, producing heads which are tennis ball size. Quick-maturing, fine-flavoured – grow it as a summer crop.
Avondefiance: The variety to choose if you plan to sow outdoors between June and August. The dark green heads are mildew-resistant. Slow to bolt and resistant to root aphid – no wonder it is so popular with commercial growers for late sowing.
Continuity: The summer lettuce with the red-tinged leaves. Long-standing and compact – a good choice for sandy soils.
Dolly: a new variety which will appeal to people who want to grow a large summer lettuce which is resistant to mosaic and slow to bolt.
Buttercrunch: The central heart of creamy leaves is hard and compact – crunchy enough to make some books list it with the crispheads. An American variety – try it for a different flavour.
Hilde: A popular choice for sowing under glass and planting out early to produce a May crop.
Suzan: Another variety which can be sown under glass in February or outdoors in spring to produce a summer crop. Hearts are large and pale green.
Valdor: One of the three popular winter-hardy varieties which are suitable for sowing outdoors in August or September to produce a spring crop. The solid hearts are dark green.
Imperial Winter: Another winter-hardy lettuce for sowing in late summer and cutting in May. An alternative choice to Valdor if you want large heads.
Arctic King: Winter-hardy – the one to choose if you want a more compact spring lettuce than Imperial Winter or Valdor.
Kwiek: A popular forcing lettuce for growing under glass to produce an early winter crop.
Premier: A forcing variety for growing under glass. Sow in October for cropping in April. The pale green hearts are large.
May Queen: Another under glass lettuce, recommended for early sowing under cloches. The leaves are red-tinged.
Kloek: A winter lettuce for cropping in January-March. A heated greenhouse is necessary – sow seed in September or October for large, solid hearts in midwinter when lettuce is scarce.
Dandie: A highly recommended forcing variety for growing under heated glass to produce a midwinter crop.

Crisphead varieties
The crispheads produce large hearts of curled and crisp leaves. In general they are more resistant to bolting than the butterheads, and their popularity is increasing in Britain. They have always been the popular group in the U.S. where the Iceberg type dominates the scene – crispheads with a solid heart and few outer leaves.
Webb’s Wonderful: The No. 1 crisphead lettuce in Britain – all the catalogues list this large-hearted frilly lettuce which succeed even in hot summers.
Windermere: Another excellent frilly crisphead for summer cropping – sow outdoors in March-July or under glass in February. Can be grown in a cold frame as a spring lettuce – preferred by some experts to Webb’s Wonderful.
Avoncrisp: Pick this one if you are bothered about lettuce troubles or if you are sowing for an autumn crop. It is mildew-resistant, shrugs off root aphid and is not likely to bolt.
Great Lakes: A large, spreading crisphead. It’s the original summer crisphead lettuce which came to use from America.
Iceberg: You can buy the seed of this super-crisp white-hearted lettuce which is becoming increasingly popular on the supermarket shelves. Sow in spring or early summer.
Lakeland: An Iceberg-type of crisphead which has been bred to be more reliable in Britain than the original Iceberg variety.
Marmer: Something new – the first crisphead for growing under glass. Iceberg-type – sow in October in an unheated greenhouse and cut in April.

Loose-leaf varieties
These varieties do not produce a heart. The leaves are curled and are picked like spinach – a few at a time without cutting the whole plant. Sow seed in April or May.
Salad Bowl: The basic variety – an endive-like plant which produces intricately cut and curled leaves which make any salad look more interesting. Pick the leaves regularly and the plant will stay productive for many weeks.
Red Salad Bowl: A must if you’re a Salad Bowl fan – this variety is grown in the same way as the standard green variety but the leaves are reddish-brown.

Troubles
Outdoor lettuce is an easy crop to grow, but it is not easy to grow well. You must guard against soil pests, slugs and birds; in cool, damp weather the twin major diseases (downy mildew and grey mould) can be destructive. Above all you must try to prevent any check to growth. Crops grown under glass are vulnerable to an even wider range of plant troubles, but few of them are serious in a well-grown crop.
Downy Mildew
Bolting
No Hearts
Ring Spot
Slugs and Snails
Root Aphid
Eelworm
Aphid
Grey Mould (Botrytis)
Cutworm
Lettuce Root Maggot
Mosaic Virus
Tipburn