Growing Lettuce in the Winter
Shop-bought lettuce is available all year round, but for the home gardener growing lettuce in the winter is can be challenging. For salad lovers, there is nothing nicer than a crisp, fresh salad, even in winter. Without the many varieties of lettuce, winter’s menu would be dominated by the brassicas, which are delicious and healthy but also have their limitations.
Lettuce has a longer season than we give it credit for. Sowing starts in January and goes through to May in warmer, less frosty gardens, starting again in August and September with summer varieties that are more heat tolerant. In addition, more and more lettuce varieties are available in seedling six packs from garden centres, which means that lettuce seedlings can still be planted out in June and July, going right through to September.
The key requirements for growing lettuce in winter are full sun, fertile soil, protection from the cold (even mild frost) with frost cloth, and consistent watering that keeps the soil evenly moist. Make it a habit to cover lettuce with frost cloth every day, from late afternoon (to trap in the heat), and remove it the next morning. That way you won’t lose your crop to an unexpected night chill.
Alternatively, growing lettuce in winter can be achieved using plastic-covered mini-tunnels, or protect individual plants with a home-made cloche made from a 2-litre plastic cool-drink bottle (with the base cut off) placed over the plant. Take off the cap so that air can circulate. Give a kelp-based liquid feed once a month. A high-nitrogen feed could make the leaves bitter, Watch out for snails (not a big threat in winter) and protect from birds if necessary. Other than that, lettuce is a very easy, undemanding crop to grow.
All lettuce varieties can be harvested as micro-greens two weeks after germination. Cut off the plants at ground level. Loose-leaf, butterhead and cos/romaine can also be grown as baby greens and cut about 28 – 35 days after germination. Iceberg is not suitable as a baby green. Cos/romaine and butterhead lettuce can be treated like loose-leaf lettuce by picking the outer leaves rather than waiting for the heads to form. Alternatively, the leaves can be picked until a central stem begins to form. Loose-leaf lettuce is regarded as a cut-and-come-again lettuce, which means that the outer leaves are picked as soon as they are large enough. Plants can also be harvested by cutting off all the leaves above the crown so that it regrows. Cutting every other plant in this way will give remaining plants more space for growth. Pick iceberg lettuce when the head feels firm and round. Do not harvest the outer leaves. Pull out the plant after harvesting.
Best ways to store lettuce
- Stored correctly, lettuce can last up to two weeks in the crisper drawer of a refrigerator:
- Wrap an unwashed iceberg lettuce in paper towel or cling-wrap or pop it in a Ziplock bag. Wash and spin the leaves before using.
- Wrap the leaves of romaine/cos lettuce in paper towel to absorb excess moisture.
- Thoroughly wash loose-leaf varieties with clean water and dry before storing. Roll the leaves in several layers of paper towels or a kitchen towel, then seal in a plastic bag.
- Keep lettuce away from ethylene-emitting produce such as apples, plums and grapes, because ethylene can cause lettuce to wilt.
Iceberg/crisp-head lettuce forms round heads and has the longest growing cycle. Plants need more space than loose-leaf varieties. Iceberg has a mild taste and is generally eaten raw in salads, used in sandwiches, as lettuce cups and in dishes that call for shredded lettuce, like tacos.
Cos/romaine lettuce is upright growing with flavourful, nutritious leaves. It tolerates both cold and heat. The outer leaves are firm, deep green with a thick white rib. Closer to the head the leaves get smaller and lighter, almost white, and this is the tastiest part of the lettuce. The leaves are crunchy, with a mild, slightly bitter flavour. Besides their salad uses, the leaves stand up well to being grilled, braised with cooked vegetables and meat, added to soups and chopped into stir-fries.
Butterhead has soft green or red-tinged leaves that almost melt in the mouth, with a mild, sweet taste. It forms small, loose heads that are ready to harvest within 60 days. The outer leaves can be picked during the growing cycle but bruise easily. Handle carefully when picking and when preparing for salads, sandwiches and wraps. Loose-leaf lettuce come in shades of green and red, with frilly, curly or lobed leaves. The leaves are not as crunchy as head lettuce but are nutritious with a fresh, mildly bitter and nutty taste. Varieties include ‘Lollo Rosso’ (red), ‘Lollo Bionda’ (light green) and oak leaf (a type of butterhead). For an extended supply, sow or plant a new row every 7 – 10 days. Cut the older leaves to allow new younger leaves to form. The leaves are good for salads, as a garnish or as a base for hot or cold dishes.
Batavia lettuce is known for its good heat tolerance but also does well in winter. There are different types of Batavia lettuce: some are like Iceberg and others are cut-and-come-again types. The tender ruffled leaves with sweet midribs come in a variety of colours. Being slow to bolt, they can extend the lettuce season well into summer.