10 min read August 27, 2024 by Simon Way

How To Harvest Lettuce: Everything You Need To Know

In this blog post, we will discuss the main types of lettuce you can grow and how they differ, give a few tips on planting, how to harvest in a sustainable way, and tell the ones that are good to eat. We will also look at some tips on storing lettuce after harvesting and take a look at the tools you will need when harvesting.

Different Types of Lettuce

Once you have decided that you want to grow lettuce, you will need to decide which type to grow. Rather than describe the literally hundreds of varieties of lettuce, here we will take a look at the five main types into which they can be classified, each of which has numerous cultivars with varying leaf shapes, colors, and flavors.

Crisphead (Iceberg) Lettuce

Crisphead lettuce, also popularly known as iceberg lettuce, is a popular type with a compact, spherical head of tightly packed, pale green leaves. It is valued for its crisp texture and mild, refreshing flavor, making it a staple in salads, sandwiches, and as a garnish. While it is lower in nutritional content compared to darker leafy greens, iceberg lettuce is high in water content, providing hydration during the hot summer months, and also contains small amounts of fiber, vitamins A and K, and essential minerals.

Romaine (Cos) Lettuce

Romaine lettuce, also known as Cos lettuce, grows into a tall head with sturdy, dark green, elongated leaves and firm ribs. Known for its crisp texture and slightly bitter taste, particularly in the outer leaves, it is one of the more heat-tolerant types of lettuce and is commonly used in salads, especially Caesar salads, and Middle Eastern cuisine. The paler, more tender inner leaves, called "hearts," are also prized.

Butterhead Lettuce

Varieties of Butterhead lettuce, include Boston and Bibb, and it is known for its soft, tender leaves and mild, slightly sweet flavor. It forms loose, round heads with buttery-textured, pale green leaves, which sometimes exhibit a reddish hue. Popular in salads, sandwiches, and wraps, this lettuce is valued for its smooth texture and delicate taste.

Leaf Lettuce

Leaf lettuce, also known as loose-leaf lettuce, grows in loose clusters rather than forming a tight head. Its leaves can be smooth, curly, or oak-shaped and come in green and red colors. Known for its tender texture and mild flavor, it is popular in salads, sandwiches, and garnishes. Leaf lettuce is versatile and easy to grow, often harvested as a “cut-and-come-again” crop.

Stem Lettuce (Celtuce)

Stem lettuce, also known as celtuce, celery lettuce, or asparagus lettuce, popular in Chinese and other Asian cuisine, is cultivated primarily for its thick, crisp, and mildly flavored stem rather than its leaves. The stem, which can grow up to 10 inches long, has a nutty, slightly smoky taste that becomes more pronounced when cooked. Celtuce is versatile in stir-fries, salads, soups, and pickling. Its leaves are also edible, but less frequently used.

Tips For Planting Lettuce

After choosing the right type of lettuce to grow considering your climate (most types can be grown in temperature or cool climates, but if you live in a hot climate you might want to grow the loose leaf or butterhead varieties that are more tolerant of the heat), plant the lettuce in well-drained, fertile soil with a pH of 6.0-6.8. The seeds should be shown shallowly, about 1/4 inch deep, in early spring or late summer. Seedlings should be spaced at appropriate intervals and given adequate moisture. Lettuce thrives in cooler weather, partial shade in warm climates, or full sun in cooler areas. Thin and transplant seedlings as needed. Watch for pests like slugs and aphids and avoid overhead watering to prevent disease. Harvest leaf lettuce as needed or head lettuce when fully formed.

Harvesting Lettuce

In this section, we will look at tips for harvesting lettuce in the right way, which is, after all, the main topic of this article. We will start by looking at how to harvest the lettuce in a way that it will keep growing. We will break this down by the approach required for each major type.

Harvesting Lettuce So It Can Keep Growing

Crisphead (Iceberg) Lettuce

If you want your Crisphead lettuce to keep growing after harvesting, unfortunately, you are out of luck, it is usually harvested as a full head when mature. Whether you harvest it in this way, by cutting it at the base when fully formed, or whether you choose to pick the outer leaves first, it does not regrow.

Romaine (Cos) Lettuce

When it comes to Romaine lettuce, it can regrow depending on how it is harvested. If you harvest the outer leaves first, and leave the stem and the crown, which is the central growing point, intact, then the plant will continue to produce new leaves from its center. If you undertake whole plant harvesting and cut the entire plant at the base, provided you leave an inch or two above the stem, the leaves may grow back (though possibly smaller and less vigorously than the first time.)

Leaf Lettuce and Butterhead Lettuce

In the case of both leaf lettuce and butterhead lettuce, if you harvest the outer leaves and leave the inner leaves and crown intact, the plant will continue to produce new leaves, enabling multiple harvests. If you cut the entire plant a few inches above the soil, the plant may grow new leaves, although less vigorously over time.

Stem Lettuce

Like iceberg lettuce, stem lettuce is not typically harvested in a way that it can regrow, as the focus of stem lettuce, as the name suggests, is the stems, although the leaves can also be eaten. For this reason, it is harvested as a whole plant.

What To Do After Harvesting Lettuce To Promote Growth

For lettuce plants that can regrow, there are some things you can do to aid the process. Firstly, if you are just harvesting leaves, you should harvest regularly as this encourages regrowth and can prevent “bolting” (this is when the plant starts to flower and produces seeds). Also, immediately after harvesting, you should water the plants to reduce stress and promote growth. Apply a light dose of balanced fertilizer to provide nutrients and protect the plants from any extreme weather conditions.

How To Harvest Lettuce Heads

When harvesting lettuce heads, it Is better to harvest them early in the morning when the leaves are full of moisture and are crisp. Harvesting them at this time will prolong the freshness of the harvested heads. Use a clean sharp knife or a set of garden shears to cut the lettuce heads at the base of the plant just above the soil. For some types like butterhead and iceberg, if the soil is loose then you can also gently twist and pull the head to release it.

How Many Times Can You Harvest Lettuce?

Naturally, this also differs depending on the type of lettuce and harvesting method. Loose-leaf lettuce allows for multiple harvests every few days to every week, and this may be up to a couple of months. 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. Proper care, such as adequate watering, fertilization, and protection from pests, can extend the plant's productive period.

How To Tell If A Lettuce Plant Is Still Good To Eat

One of the best ways to check if a lettuce plant is still good to eat is to check for freshness by looking at the color and texture of the leaves. Healthy lettuce leaves should be vibrant green and crisp. You should avoid leaves that are wilted, slimy, or have brown or yellow spots, as these are signs of spoilage or disease. You should also check for any unusual odors, as fresh lettuce should have a clean, mild smell. Make sure that the base of the plant is free of pests or signs of rotting If the plant has bolted, the leaves may become bitter, so taste a small piece to ensure it still has a pleasant flavor.

How To Harvest Lettuce Seeds

So far, we have focused on harvesting the lettuce head or leaves itself, but what should you do if you just want to harvest the seeds? In this case, you should allow the lettuce plant to bolt (produce a flower stalk), which usually happens in warmer weather. When the plant bolts, it will produce small flowers that turn into seed heads. Once the seed heads are fully dry on the plant, the seeds will be mature and ready to harvest. Gently shake or rub the seed heads over a container to release the seeds. Store in a cool, dry place in an airtight container.

Tips For Storing Lettuce

In order for lettuce to remain in the best shape for eating, it is necessary to make sure it stays crisp and dry. Lettuce should generally be refrigerated at about 0-2℃, or at a higher humidity if possible. The different types of lettuce should be stored as follows:

Leaf Lettuce

Rinse the leaves gently under cold water and dry using a salad spinner. Alternatively, you can pat them dry with a paper towel. Store them in a plastic bag or container along with a damp paper towel to maintain moisture. Leaves can be stored this way in a refrigerator for up to a week.