For most people lettuce is the mainstay of any salad. A bigger and more exciting choice of varieties is available now than ever before, and you can grow all kinds as baby salad leaves, too.
Sowing and cultivating lettuce
When you’ve chosen the variety you want to grow, follow these steps to get going:
1. Sow the seeds
For a crop that’s associated with summer, lettuce is odd in that the seeds germinate poorly if the soil is too warm; therefore, sow on cool days or in the evening in summer. Avoid sowing if the temperature is above 25 degrees Celsius. This advice is most important a few hours after sowing and watering, because the seeds absorb moisture.
Lettuces often run to seed in hot weather, so try to avoid sowing large quantities at any one time. Growing lettuce for harvesting in early summer and early autumn is easier. You can sow a few varieties (mostly butterhead) in late summer for cropping in late autumn and early winter but these are only successful if you grow them in a greenhouse or polytunnel or under cloches (a transparent covering). Remember to choose an appropriate variety if you’re sowing lettuce for autumn and winter use.
You can treat the seeds in two different ways: sowing where they are to grow or in pots, trays and grow bags.
You can sow lettuce seed outside in rows from the end of March, as long as the weather isn’t too cold. Sow about 1 centimetre deep in rows and cover. Seeds start to grow within two weeks.
Your other option is to sow seed in pots and trays and transplant the seedlings into cell trays, planting the seedlings out where they’re to grow when they have three or four leaves. But lettuces don’t always transplant well, so another option is to sow two or three seeds in each cell of a cell tray and then plant out the seedlings. This method often works well and is useful for sowing in summer when keeping seed rows moist in hot weather can be difficult.
Space most varieties of lettuce 20–30 centimetres apart, depending on the variety.
Lettuces prefer moist soil that is rich in organic matter and although best in full sun you can grow them in part shade, especially loose-leaf types. Keep them watered in dry weather and free from weeds or crowded, outer leaves may rot. Lettuces are very susceptible to slug and snail damage and if you think that your seeds have not germinated, these little pests may
be to blame. Protect your seedlings as soon as they start to appear.
2. Cultivate your plants
When the seedlings appear you need to thin them to give the remaining seedlings room to mature. When the seedlings are about 8 centimetres high, carefully transplant some to grow in another row. Choose a dull day to do this and water the row the night before. Lift the spare seedlings carefully, replant them immediately in their new home, and water them. The transplanted lettuce matures a week or two after the others. Alternatively, you can pull up and eat spare seedlings at any stage of growth.
Harvesting and storing your lettuce
The best time to harvest lettuce is just before you need to eat it. You can harvest all types of lettuce at any stage of development but hearted kinds are mature when the centre is full and firm to the touch. Most varieties ‘stand’ (in other words, remain at their peak) for a week or two but in hot or wet weather they may deteriorate or run to seed.
Lettuce is divided into four main groups:
Butterheads are the typical soft-leaved cheap supermarket lettuce with creamy yellow hearts. They are quick to mature and are generally for spring and summer sowing. Once the staple of most salads, butterheads are now less popular.
- All Year Round has a compact habit and is good for early sowing under cover or outside in late spring.
- Sangria is a good choice for organic growers thanks to its resistance to disease and pests. Pale green hearts and red outer leaves make this a distinctive-looking variety.
- Tom Thumb is a compact variety, ideal for raised beds and pots.
Crispheads (also known as Icebergs) are easily recognizable in supermarkets by their dense, heavy heads of crunchy, crisp leaves. Crispheads are easy to grow for summer and autumn cropping.
- Lakeland produces dense heads with a compact habit.
- Sioux has an unusual appearance, with red leaves that are most intense in hot weather.
- Webbs Wonderful is a traditional variety with small, dense heads. Webbs Wonderful was grown long before Iceberg-type lettuce became popular and is still available.
Cos have upright, dense heads that are crisp and crunchy and essential for Caesar salad. They take longer to mature than other groups of lettuce, but are generally tastier.
- Counter produces dense, crisp, sweet heads and is resistant to many lettuce problems including mildew and tip burn (brown tips to leaves).
- Little Gem and Bubbles are mini-Coses, popular in supermarkets and ideal for small gardens because of their neat size – you can plant as close as 15 centimetres apart. Several ‘improved’ variants such as ‘Little Gem Pearl’ are available.
- Lobjoits Green Cos is a traditional favourite suitable for late sowing to harvest into winter or spring.
- Winter Gem is an ideal lettuce for autumn sowing for cropping in spring in a greenhouse
Looseleafs (also known as cut and come again) are adaptable and you can harvest them by picking individual leaves or cutting them off for re-sprouting. They don’t form hearts. Looseleaf lettuces come in a wide range of foliage shapes and colours. Most crop for long periods and so are useful to fill gaps between other types that may not be ready.
- Lollo Bionda forms large heads of frilly green leaves. Not the best variety for eating, but looks great and withstands heat well.
- Lollo Rosso produces large heads of red, frilly leaves.
- Salad Bowl, easy and reliable to grow, is an old favourite with flabby, soft, green leaves.
Cooking Tip: People usually eat lettuce raw, but it also makes a surprisingly good soup and also tastes good after you lightly fry it in butter or add it, shredded, to fresh, young peas.
Nutrition Tip: Green lettuce leaves are rich in betacarotene and vitamin C and red lettuce contains additional antioxidants. All types contain a little fibre, too.