Most lettuce varieties will regrow three to five times if harvested carefully. For most types, you'll want to only cut the outer leaves each time you harvest, allowing the core and roots to remain and continue growing.
Unlike head lettuce, which is typically done once the head is harvested, leaf lettuce is a “cut and come again” crop. That means you can take a few leaves at a time or all of them at once, and the plant will regrow those leaves — until the plant bolts or frost comes.
Romaine lettuce can be harvested for outer leaves several times, and typically between 3-5 harvests. Butterhead lettuce offers 3-4 outer leaf harvests or 1-2 partial head harvests. Iceberg lettuce is usually harvested once as a whole head, with limited outer leaf harvests.
Will Lettuce Regrow After Cutting Lettuce and other greens, when harvested young, will grow back at least one other time. Some varieties may grow back multiple times, but at some point they will stop growing which is why we like to succession plant.
As long as you're staying within lettuce's optimal growing conditions, you can harvest from each lettuce plant at least three or four times in a season using the cut-and-come-again method, and about two to three times using the ponytail chop method (but you'll get more leaves with each harvest this way).
Top Cut-and-Come-Again Lettuce Varieties
'New Red Fire,' as the name suggests, is a red-leafed variety with superb tolerance to bolting. Large leaves are green at the base and deep red at the edges. 'Amish deer tongue' is much tastier than it sounds!
Depending on the variety and time of year, lettuce generally lives 65–130 days from planting to harvesting. Because lettuce that flowers (through the process known as "bolting") becomes bitter and unsaleable, plants grown for consumption are rarely allowed to grow to maturity.
Will a bolted lettuce plant regrow? If you cut a bolted lettuce plant down to its base, it will regrow, unless the weather gets too hot, which can kill lettuce plants.
Lettuces prefer cool temperatures, but by sowing every week, choosing heat-tolerant varieties, and using shade-cloth tunnels, I can produce lettuce right through my Zone 7 summers. It is easy to keep the supply going right into winter by growing winter varieties in cold frames or tunnels of row-cover fabric.
As long as you don't remove the whole romaine lettuce for a harvest, including the roots and main stem, you can wait for the romaine lettuce to regrow even after cutting it. More specifically, a single lettuce plant can regrow and be harvested three to four times in one season if you employ the leaf-cutting technique.
Lettuce has shallow roots, so plants need consistent watering. Check at least twice a week and water if the soil is dry down to 1 inch deep. Containers of lettuce need to be watered more frequently than garden beds, especially in the summer.
The trick to a perpetual crop is to plant seeds at different times. A new seeding every two weeks works for me. This will depend on how much lettuce you eat and how much you grow at any given time.
Although lettuce grows fastest in full sun, it is one of the few vegetables that tolerates some shade. In fact, a spring crop often lasts longer if shaded from the afternoon sun as the season warms. You can grow lots of lettuce in a small space, even a container.
Lettuce grows best in a temperature range of about 45 to 75 degrees. In weather hotter than that, the leaves become bitter to the taste. When leaf lettuce bolts—which means they begin to send up its flower shoots—it's a signal that the production of edible lettuce is done for the season.
However, you too can grow fresh lettuce during the summer by choosing the correct varieties, paying attention to the planting location, using shade or seasonal covering, and watering sufficiently.
Video: How to Regrow Romaine Lettuce from the Stem
Unlike regrowing green onions or regrowing celery, you won't be able to regrow a full head of lettuce. You'll just regrow a few leaves 2-4 inches long. Enough for a sandwich. Regrown lettuce will bolt (send out a seed stalk) before it grows a full head of lettuce.
Those who grow their own lettuce know about vegetables that self-seed firsthand. Invariably, the lettuce will bolt, which simply means that it goes to seed. Literally, you can have looked at the lettuce one day and the next it has mile high flowers and is going to seed.
Common Causes of Bitter Lettuce
Most gardeners will tell you that bitter lettuce is the result of summer heat; lettuce is known as a cool season vegetable. When temperatures rise, the plant snaps into maturation mode and bolts -- sends out a stalk and flowers. It's during this process that bitter lettuce is produced.