The humble lettuce, stalwart of sandwiches, side salads and much more, is easily overlooked as a serious ingredient, but there is a gulf of difference between a buttery, sweet, tender leaf and one that is bitter from poor growing. Timing is important: if you hit the sowing windows at the right point, you don’t need to sow a great amount. For my household of two, both of whom love lettuce, we need 10 full-grown plants to pick from at any given time of year. For a family of four, where salads are serious business, I would grow between 15 and 20 plants.
Rather than harvesting a whole head of lettuce, though, you should remove only the lower, mature leaves, taking up to only three leaves per plant in any one picking. If you grow them in this way, it is possible to start picking once the plants are six weeks old and continue for about 14 weeks before the plant is exhausted. To pick whole heads, it’s best to wait until the 10-week mark, so you’d need to sow roughly double the amount of seed to get the same harvest as from picking individual leaves.
Many of you will already have sown lettuce in early spring. A second sowing now, or any time before the end of May, will yield supplies to last to the end of summer. You can then make another sowing around the last week of July to take you through the winter (although those lettuces will need protecting from September with cloches, fleece or tunnels).
You can make one final sowing in September; this lot will need winter protection in either a polytunnel or a greenhouse, and won’t be picked until next March, tiding you over until the first spring lettuces are ready.
I like Parris Island cos, which is a sweet, crunchy people-pleaser – I’ve yet to meet anyone who doesn’t like it. Give it plenty of space, because it can grow up to a huge 3kg per lettuce. My other go-to is Morton’s Secret Mix, (available from realseeds.co.uk) which would be my top choice if you’re only going to buy one packet, because you get butter, leaf, head and tongue varieties in reds, greens and splashes.
Spacing is everything: leave 25cm-30cm in each direction between plants, or use a 30cm-diameter pot for each lettuce, so that they can have a decent root run. This will result in sweeter lettuce. The leaves only become bitter and tough when the plant is stressed from lack of water, either through competition or – and this is particularly true of container-grown plants – if the soil regularly dries out. For summer-grown lettuce, a little shade is often necessary, too. Finally, to deter moisture-loving slugs, water early so the plants are dry by the time they are out munching after dark.