Lettuce has a few characteristics with which gardeners should be familiar.
1 It has a season when it grows most healthily – from April to July in Britain – and outside this period it is prone to problems such as root aphids and mildew in late summer and autumn, and frost or stem rot in cold, wet winters
2 It is easiest to grow when raised as plants in a sheltered environment, out of reach of slugs. Baby seedlings are vulnerable to many pests whereas well rooted young plants can resist some tribulations.
3 Many varieties of lettuce can be picked regularly, say once a week, of their lower leaves, when planted with enough room to grow, say 9×9″ or 22x22cm. Don’t use a knife but twist and rotate all larger leaves until they detach, leaving the small central leaves to grow again. This enables harvests for up to twelve weeks in summer, off the same plants, meaning much less sowing than is normally recommended. I developed this method in 2003 and it is catching on quite widely now.
4 The above method works well for many cos and batavian varieties sold for hearting.
5 Red lettuce resist slugs more than green ones, but are of more bitter flavour.
6 A little known variety, Grenoble Red, sold as a hearting lettuce, works well as a leaf lettuce picked as above. I find that when sown in early September as a module plant, set out in a tunnel or greenhouse in October, it will crop from November to June, picked fortnightly until March and then weekly.