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.
The harvests never stop. If you decide you want lettuce tonight for dinner, all you have to do is pull off the oldest leaves of the plant, give your plant some days to recover, and then you'll be able to return for more and more leaves. That's because lettuce plants grow from their center, from their heart.
Keep an eye on the inner leaves of the romaine head and give them time to continue growing. Once they've opened up and matured, they're ready to harvest. This process can happen quickly, so check on your garden daily. You'll be able to get 3–4 additional harvests by picking only the mature, outermost leaves each time.
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.
Baby romaine leaves are ready to pick when they reach a usable size. Larger leaves and romaine heads can be harvested when they're a dark green color and at least 6” high.
Like every living thing, lettuce needs to ensure its continued reproduction. This is why lettuces “bolt” – the plants begin to grow upwards, producing less leaves and eventually blooming.
A head of lettuce is normally 4 meals for me as a main (dressed up, of course), at least twice that as a side. But if your crowd is all about that lettuce then maybe you'll need a third head.
All you need to do is fill a large bowl with hot water (about 120 degrees Fahrenheit). Submerge your wilted greens, and let them soak until they perk up, anywhere from 10 to 30 minutes. Then, drain them and cool them off again. If you're using them immediately, use an ice-water bath.
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. Stem lettuce is harvested as a whole plant.
Romaine lettuce requires well-drained, nutrient-rich soil in order to thrive. The soil should also be loose and loamy, as compacted soil can lead to yellowing and wilting of the leaves.
Once you've harvested the whole head, the remaining romaine roots will recover from the cut and sprout new leaves after a week or two.
Watch the lettuce regrow
I removed the lower leaves so that the plant would concentrate it's energy on regrowing, not dealing with the leaves left behind. You'll be able to get away with 2-3 harvests per plant, after which they will most likely become too bitter or tough.
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.
You can identify a bolting lettuce plant by its stretched-out, leggy appearance. You'll see a slender stalk where the leaves are attached. This is a sign that it's time to harvest the plant all in one go. Once it starts bolting it will no longer produce more tasty leaves.
Head lettuces are suitable for a single harvest. In contrast, leaf lettuces are more suited for plucking a few leaves here and there over a more extended period. Looseleaf lettuce can also be harvested 1–2 inches from the ground and left to regrow a second crop of leaves, often several times.
Harvest in the morning to keep your leaves their freshest and minimize wilting. Use your harvesting knife and try to cut the head of the lettuce as close to the soil as you can. Remove any damaged outer leaves until you have only a clean center head. Do not rinse your lettuce unless you plan to eat it immediately.