HOW TO CARE FOR LETTUCE IN THE UK
When your lettuce seedlings emerge they should be thinned to the correct distance apart to ensure they can grow to their full size without over-crowding.
Aside from that they need little care other than weeding, a little feeding and lots of water in dry conditions.
If you harvest lettuce regularly you will not only have a crop over a longer time but you will also be able to re-plant in the same position for even more crops.
The ideal situation when thinning lettuce is to let them grow just large enough so that the thinnings can be used in salads and sandwiches – young baby lettuce really is delicious. Initially when the seedling emerge thin to about 15cm / 6in apart. Let the lettuce grow until the leaves start to touch and then thin to their final distance apart of 30cm / 12in. Smaller lettuce such as Tom Thumb can be grow at slightly less distance apart. The second thinnings are ideal as baby lettuce.
Lettuce are very prone to attack by slugs and snails with the tiny seedlings being especially vulnerable. See our page on lettuce pest and diseases here.
WATERING AND FEEDING LETTUCE
Lettuce aren't heavy feeders but a good handful of blood, fish and bone worked into the top soil every square metre / yard will give them all the nutrients they need. However, what lettuce really do appreciate is regular watering in dry and warm conditions. They need water not only to swell their leaves but also to cool the soil in warm conditions. As with all vegetables, regular weeding is needed to stop them competing for moisture and soil nutrients
Lettuce never keeps for long after harvest, it's best eaten on the same day. Supermarket lettuce and especially those bags of lettuce leaves are highly treated with chemicals such as chlorine to extend their life.
Unfortunately they never taste so good as home-grown lettuce and they certainly contain many chemical and pesticide residues. So don't be disappointed if your lettuce keeps for a day or so at most in the fridge, that's because you have grown and harvested a natural product without the aid of sprays and chemicals.
How much you harvest at a time depends entirely on how much you need. All lettuces respond well to having the outer leaves harvested, it encourages more growth later on. If you want to harvest a whole lettuce take hold of the lettuce at its base and gently tease the roots from the soil. Lettuce will store better if the base stem is left on the plant. Store lettuce in the fridge but don't freeze.
Don't leave lettuce in the ground too long because it will start to set seed (a process known as bolting) and this will make the leaves taste bitter. Harvest when young and tender is the rule. When you have harvested a few of your lettuce it's quite possible to sow more seeds in the same place for a crop later on.