How to grow Winter Lettuce

How to grow Winter Lettuce

Lettuces can be grouped into four broad categories according to how they grow: crispheads, loose-leaf, cos and butterheads. Winter lettuces are simply very hardy varieties of these types.

Crisphead lettuces are one of the most widely available types of lettuce you’ll find in the supermarket. The leaves are tightly folded together to form a dense ball. Cos lettuces are upright, taller lettuces with firm leaves.

For a creamy lettuce leaf texture opt for butterheads, which have a tender, smooth character and an almost buttery consistency. Loose-leaf lettuces have many variations including red lettuce leaves, but none of these form heads, and can be used as cut and come again lettuce.

Lettuces are always a winner on the veg plot, but what many may not realise is that they can be grown quite successfully throughout autumn and, given the right varieties and a little protection, on into winter too.

There are a number of surprisingly hardy lettuces that will help you to extend the season, opening up the possibility of mid-winter salads when pickings are lean elsewhere. Fresh, healthy leaves at the coldest times of year will be appreciated far more than the ready supplies of summer – the quantity may not be as much but the taste will seem all the better.

Like their summer counterparts, winter lettuces are available in a range of leaf types and can be sown now to get the autumn season off to a rewarding start. Sowing every few weeks through to October should ensure a leafy supply through to spring when less hardy varieties can be grown. If you are lucky enough to have a greenhouse or polytunnel then the task is even easier, although anyone can grow winter lettuces given a little care and attention.

Winter lettuces are no different to summer ones in their requirements, and in many ways starting them off later on in the season is easier as the heat and dry of the summer has passed. Lettuces are cool-season crops and hot weather can seriously hamper both germination and growth rates of these thirsty veg.

Choose as sheltered and sunny a spot as possible for your winter lettuces, as the protected conditions will ensure that plants make the most of any mild spells during the cooler months. Plants will not grow at all in very cold or frosty weather, and a sunny position means frosted ground quickly thaws and growth soon resumes.

Prepare the ground by digging in some organic matter – homemade compost is ideal. You can also grow lettuces in pots or window boxes of general purpose compost mixed with some soil-based John Innes growing medium. This will give it a bit more substance and prevent the compost becoming too wet during the moist autumn and winter months.

Dug soil should be raked down to a fine tilth, with any debris or large stones removed to the side of the plot. In warmer parts of Britain it should be possible to grow lettuce outdoors with no protection, but, in most areas the addition of a cloche or horticultural fleece during cold spells will increase the chances of success and the length of the harvest. Make sure you have suitable covers to hand before poor weather arrives.

How to sow winter lettuce

Sow winter lettuces in rows spaced 30cm apart. To get a good, straight row set up a string-line stretched taut between two pegs and draw a garden cane along it to mark out drills that are approximately 1cm deep.

Sow seeds very thinly into the bottom of the drill then pinch it closed before tamping down along the length of the row. Use the back of a rake to press the soil down into contact with the seeds. Watering thoroughly along the row will settle the earth further and help get things started if the conditions are dry. Start sowing in August for autumn and winter crops and continue through to the end of October.

Seed may also be sown into seed tray modules for later transplanting. This is a useful option when only a few plants are needed and will mean a minimum of wasted seed. Fill trays with seed or multipurpose compost and sow a few seeds into each module.

Germination should occur within two weeks and often within one week, so you won’t have long to wait. Once they appear, thin lettuces to leave one seedling per module.

Lettuce seeds can fail to germinate if sown in heats of above 25°C. If this seems to be a problem on your plot, try sowing at a cool time of day and watering afterwards to reduce the soil temperature. Seed sown directly into the ground should be thinned in two stages. This has the advantage of acting as an insurance policy against the poorer winter conditions and excess plants may be used to gap up any spaces that appear within the rows.

The first thinning of seedlings can be completed as soon as the young lettuces are large enough to handle. Pull away plants to leave one every 5cm. As they grow on to reach 3-4cm high, thin them to their final spacings, which will vary according to the type of lettuce – check the back of the seed packet for details.

Smaller varieties such as ‘Tom Thumb’ will need just 15cm between them, while large varieties may need as much as 30cm between plants. Don’t waste the plants taken as the second thinning – you can eat them or replant them elsewhere.

Plant out module-raised seedlings as soon as they have five or six pairs of adult leaves. Dibble a hole for each module and gently firm it into position before watering into place. Space them at their final positions but keep a few extra between the rows to gap up any that fall prey to pests, diseases or the weather.

As the weather cools down and frosty nights creep in, consider protecting plants with cloches or horticultural fleece. This will keep your crops a few degrees warmer. Solid cloches have the added advantage of keeping plants a little dryer during prolonged rainy spells, preventing waterlogged soil conditions.

Growing undercover

Home-growers with a permanent polytunnel or greenhouse will have the most success with winter lettuces. In these structures the conditions will be one season ahead of that outside – warmer and free from persistent winter rain that can badly stunt outdoor lettuce. Sow seeds into modules on the propagation bench and plant them out into the beds as soon as they fill their cells. Growth will continue in all but the coldest spells so make sure the plants are kept watered throughout the season.

Growing winter lettuce in a greenhouse can be done in a number of ways - particularly the easy-to-grow cut-and-come-again types of loose-leaf lettuce, can also be sown into spent grow bags that were used for growing summer-fruiting crops such as tomatoes. Simply fork over the bag’s contents to break up any clods and add a light sprinkling of general-purpose fertiliser such as blood, fish and bone meal or chicken manure pellets.

Sow directly into the bag – broadcasting the seed thinly and evenly over the surface – and lightly fork this into the top centimetre of compost. Water with a watering can fitted with a rose and keep the bag moist until the first leaves are ready for picking in as little as five to six weeks.

Growing lettuce indoors is also possible if you have a sunny windowsill on which you can place your pots - perfect for mini leaves plucked straight away for use in the kitchen.