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23 February 2021

How to grow lettuce

Find out how easy it is to grow crunchy and crispy lettuce for salads
Watering lettuce
CT
Ceri Thomas

Lettuce is quick and easy to grow. It will do well in a container on your balcony or patio if you don't have a garden.

How to grow lettuce: month by month

January February March April May June


SOW SOW/HARVEST SOW/HARVEST

HARVEST
July August September October November December
HARVEST SOW HARVEST HARVEST



Best lettuce varieties

Best Buy crunchy lettuce
What it looks like Variety name Yield per plant
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3.1kg
This mini cos lettuce was easy to grow. Virtually all the seeds germinated and developed into good-quality plants. When fully grown, the heads had a neat shape and an appetising deep-green colour. This was matched by their pleasant crunch and good flavour, which had no trace of bitterness. They lasted well in the ground, beginning to bolt around the middle of July when most varieties were affected by the heat.
What it looks like Variety name Yield per plant
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3.9kg
A tall romaine type of lettuce, ‘Stryker’ was easy to grow from seed and gave us plenty of strong-growing, healthy plants. They developed into large, well-shaped heads with plenty of good-quality leaves. They had an appealing, deep-green colour and a lovely sweet flavour that didn’t disappoint, as well as a firm, crunchy texture. They began to bolt in mid-July, but by that time, most varieties had started to succumb to the heat.
What it looks like Variety name Yield per plant
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2.4kg
Although ‘Thimble’ is described as a mini-romaine variety and the heads were quite small, they were densely packed with plenty of good-quality, dark-green leaves. These were firm with a decent amount of crunch and good flavour; not particularly sweet but not bitter either. The seeds germinated very well and grew on strongly, so it was an easy variety to grow and it was one of the last to start to bolt in late July.
Best Buy cos lettuce
What it looks like Variety name Yield per plant
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705g
If you prefer sweet-tasting lettuce, this is a great choice. It was sweeter by far than our other Best Buy full-sized cos. It has bubbly-textured, glossy green leaves that stay crisp for quite a while after cutting. It germinated well, and quickly matured into large heads that had quite dense hearts for a larger variety. The plants left in the field didn’t suffer tipburn, and didn’t bolt until eight weeks after planting.

What it looks like Variety name Yield per plant
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862g
If you’re looking for an easy-to-grow, standard-size cos lettuce, this older variety is a good choice. It germinated really well, and grew vigorously to form very large heads with fairly dense hearts. The bright-green leaves didn’t taste particularly sweet, but they didn’t suffer any tipburn in the sun and stayed reasonably crisp after cutting, which is ideal if you have to bring your harvest back from an allotment.

What it looks like Variety name Yield per plant
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272g
Although it wasn’t quite as crisp as other varieties, this germinated well and produced uniform, pale-green leaves that were exceptionally sweet and a firm favourite with our assessor. We got a good crop, and the leaves didn’t burn in the hot sun, so we didn’t have to lose much of the plants when they were harvested. The plants we left in the ground stayed usable longer than the other Little Gem varieties, for more than seven weeks after planting.

What it looks like Variety name Yield per plant
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292g
This is a familiar and popular variety that’s sold widely in supermarkets. It was quick to germinate and the leaves were soon ready to pick. It produced an excellent yield of dense hearts and none of the plants got burnt in the sun. The leaves were crisp and sweet-tasting, ideal for salads or cooking.

What it looks like Variety name Yield per plant
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214g
The deep-red leaves fade to green or even yellow in the heart of the lettuce and would certainly add a splash of colour to any salad. During our trial, the plants hearted-upwell to form tasty heads of lettuce, and they didn’t bolt. Our assessor found that the leaves were not quite as sweet-tasting as the green lettuce varieties, and they were softer, so they would be good for using in sandwiches.

How we test lettuce

We sowed seeds of a number of lettuce varieties indoors in May and the lettuces were planted outside in beds in the first week of June. We protected them with an insect-proof mesh to prevent any attack on the leaves and roots, and, as there was no rainfall during the trial, watered them as needed, to stop the soil drying out. All varieties were harvested when mature in early July, and then assessed, tasted and weighed, but some heads were left in the ground to see how long they would last before problems set in. The weather was very hot during the trial, and the high temperatures led to many varieties bolting (producing flowers) sooner than we would normally expect.

When to sow

Sow seed indoors from mid-February in modules or seed trays filled with a Best Buy compost for sowing seeds. Grow seedlings on in modules or small pots in a cool, well-lit place until they’re large enough to plant outside.

Alternatively, sow seeds outdoors from late March in well-prepared, loose soil in shallow, straight drills. Keep the soil moist after sowing until the seeds are growing strongly. Thin the seedlings to around 30cm apart.

If you're planning to cut the whole lettuce heads at harvest, sow at intervals of three to four weeks to keep a regular supply of lettuce going. If you're planning to just harvest the outer leaves, you don't need to sow as often - a March sowing will provide leaves from spring to summer, and an August sowing will provide leaves from autumn through winter.

Caring for your plants

Planting

Plant in well-drained soil in sun or semi-shade, or into pots of a Best Buy compost for containers. Plant early sowings under a cloche or cover them with fleece to protect them to trap the sun's warmth and protect from cold winds.

Weeding

Weed regularly, especially when the plants are small.

Watering 

In dry weather, water the soil around the roots of the plants in the ground at regular intervals so the soil doesn’t dry out completely. Try to avoid wetting the leaves. Plants growing in pots will need watering more frequently; more than once a day in hot, dry weather. Touch the compost to check if it feels dry before watering.

How and when to harvest

Harvest in: June to October from a spring sowing, and winter and spring from an August sowing

Head-forming lettuces should be picked when the head feels firm. Cut the lettuce away from the roots at the base of the head.

Loose varieties can be picked as single leaves when they reach an edible size. Pick leaves from the outside and the plants will continue to grow and produce further harvests. Don't be alarmed if they start to look like palm trees with a trunk below the leaves.

Common growing problems

Slugs and snails

Slugs and snails will eat leaves, particularly when plants are small. Pick off any that you find. Protect with organic slug pellets made from ferric phosphate, which isn’t thought to be harmful to wildlife, or water biological-control nematodes on to the soil at six-week intervals (these only kill slugs).

Read more about slugs and snails.

Aphids

Aphids can attack roots and leaves. Cover plants with insect-proof mesh to prevent infestation.

Read more about aphids.

Grey mould

Grey mould (botrytis) infects leaves in damp, humid weather. This fungal infection begins as discoloured patches on leaves and grows into fuzzy, grey patches. Remove infected parts of the plants if spotted early, or pull up the whole plant if it’s badly infected.

Read more about grey mould.

Tipburn

Tipburn is caused by a lack of calcium, often when the uptake of water is reduced in dry soil, and the symptoms are brown, wilting leaf edges. Leaves also blister as the skin fails to keep up with the speed of growth caused by hot weather, and heads can split if watering is irregular.   

Read more about tipburn.

Bolting

High temperatures don’t suit lettuce, so when it gets above 25°C, problems start to emerge. Bolting, when the plant starts to produce a flower spike in the centre, is the most obvious one, but the leaves will start to develop a more bitter flavour even before you spot the flower spike.  

Read more about bolting.

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