How to plant and grow Lettuce

There are two ways to grow any type of lettuce. The first and traditional one is to sow them directly into the ground where they are to grow (including into any kind of container), in drills or broadcast. You then thin them carefully as soon as they are large enough to handle and thin again a few weeks later (eating the meltingly tender thinnings, roots and all) so that you are left with a row of maturing plants about 7.5–23cm (3–9in) apart. The advantage of sowing directly is that the roots are not disturbed by transplanting. The disadvantage is that they are very susceptible to slugs and snails (see opposite), especially at the young seedling stage and especially at this time of year when growth can be slowed almost to a standstill by a bout of cold weather. 

Nor is less handling required if you sow them in drills because the thinning process is fiddly but essential. They must also be kept watered and weed-free. I only sow direct when I use a mixture of seed such as saladesi or saladini, which I broadcast and do not thin except to eat. 

I find it much more controllable to sow the seed in plugs or seed trays, grow them into reasonable-sized seedlings and then plant out at 23cm (9in) spacing in rows on open beds or in a grid on a raised bed. I use a home-made seed compost but any bought peat-free compost will do. This system depends upon having cover such as a greenhouse, cold frame or even a porch or windowsill. 

Most lettuce take about six to ten weeks to grow sufficiently large to eat, depending on the time of year. To provide a constant supply of salad leaves, sow a few seeds every ten to fourteen days from mid- February through to early September, so as one small harvest is used up, another is ready to take its place. Or, as I do, sow a new batch of lettuce seed every time you plant young seedlings out into the beds.

Lettuce germinate at surprisingly low temperatures and many will fail to germinate once the soil temperature rises above 25ºC (77ºF). Mature plants will respond to higher temperatures by producing flower stems – bolting – and running to seed. This makes the leaves bitter. There are ways around this. If you are sowing directly into the soil, water the drill before sowing to cool the soil down. Sow in the afternoon so that the vital germination phase coincides with the cool of night. Also sow into a shaded part of the midsummer vegetable garden. 

If sowing in seed trays, put them in the shade and cover with glass or newspaper to keep them cool until the seedlings appear. If the seeds are showing no signs of life after a week, put them into the fridge for 24± hours.

Family	Asteraceae
Growing zones	N/A
Growing season(s)	cool  season:  spring  and  fall
Spacing	leaf lettuce 4 to 6 inches, head lettuce 10 inches
Start indoors or direct sow	either
Indoor sowing date	4 weeks before transplant (8 weeks before average last frost)
Earliest outdoor planting	4 weeks before average last frost, seeds or transplants
Soil temperature	40° to 80°
Fall planting	1 to 6 weeks before average first frost
Sun needs	4+ hours
Water needs	low in spring, more as temperatures climb
Harvest category	weather dependent
Keep in Mind Tip	Different varieties of lettuce vary in their heat and cold tolerances. Read seed packets to choose heat-tolerant varieties for the spring and cold-tolerant varieties for the fall.

 

Snapshot	One of the easiest, fastest, and most dependable crops in the home garden, lettuce thrives in the cool temperatures of spring and fall. Some cold-tolerant varieties even survive in the winter, especially when under cover. For a continuous harvest, sow seeds every 2 weeks during the spring and fall.
Starting	Lettuce can be started from seed indoors for a jump start to the spring harvest or for a fall crop when the late summer is too hot for lettuce to thrive. Whether starting indoors or direct sowing, scatter seeds on top of the soil and gently graze it with your fingers or a rake to lightly settle the seeds into the soil. Don’t bury the seeds, as a surface sowing will result in the best germination. Keep the area moist. Thin seedlings to desired spacing.
Growing	Once established, lettuce requires little maintenance. Ensure the area stays watered, and watch out for insects such as aphids and worms. Lettuce is a great crop to plant under vertical crops such as tomatoes, peas, and beans. The vertical crops will provide shade for the lettuce, possibly allowing a longer harvest time into the summer. Mulch well to keep soil temperatures low, which may delay bolting.
Harvesting and Storing	Harvest the outermost leaves of leaf lettuce. The plants will continue to produce from the center. Keep an eye on early summer weather, because warm temperatures and dry conditions will cause the plant to bolt and the leaves to turn bitter. For head lettuce (usually only successful in cooler climates), harvest when heads are firm.
Common Problem	When lettuce begins to form a stalk in the center, it has reached the end of its life cycle (also known as bolting). At this point, the leaves are bitter beyond edibility and you can’t do anything to change it. If space is at a premium, pull the plants and compost them, but if not, allow the plants to form flower stalks, which will attract beneficial insects.