Lactuca sativa (Lettuce)

Lettuce (Lactuca sativa) is an annual or biennial plant primarily grown for its tender, edible leaves and sometimes for its stem and seeds. Easy to grow, Lettuce comes in a wide range of colors, flavors, and textures.

• Lettuce is a member of the Asteraceae or Aster family, which includes dahlias, marigolds, coneflowers, sunflowers, and zinnias.
• Initially farmed by the ancient Egyptians, Lettuce has been used for centuries.
• Lettuce thrives in cooler temperatures, desiring full sun in cool weather and light shade in warmer weather.
• Lettuce can be grown in all climate zones and harvested from late spring through winter.
• Although generally considered a poor source of nutrients, its low calories make it a popular diet ingredient.
• Frequently used in salads, Lettuce can also be eaten in various ways, including wraps, hamburgers, tacos, and many other dishes.
• In some countries, such as China, Lettuce is typically eaten cooked, and the use of the stem is as important as the use of the leaf.

Main Types of Lettuce

There are hundreds of varieties of Lettuce. All Lettuces fall into one of 4 groups based on head formation and leaf structure.

Head Lettuce (L. sativa var. capitata)
Named after its round shape, this variety includes Butterhead and Iceberg (crisphead) Lettuces, both commonly sold in grocery stores.

• Butterhead Lettuce: Also known as Boston or Bibb Lettuce, or Round Lettuce in the UK, this Lettuce forms an open head with a loose leaf arrangement. It has a buttery and tender texture and a sweet flavor. A cup of chopped Butterhead Lettuce contains 36% of your daily needs in vitamin A. It also contains some vitamin C, iron, and calcium. Butterhead cultivars are most popular in Europe.
• Iceberg Lettuce is a most popular type of Lettuce in the United States. The name Iceberg comes from how the Lettuce was transported in the 1920s on train wagons covered in crushed ice, making them look like icebergs. Iceberg forms a tight, cabbage-like head. It has a mild taste and slight crunch and is often a key ingredient in salads. It does not contain as many vitamins and minerals as other lettuce varieties. A cup of chopped Iceberg lettuce contains 7% of your daily needs in vitamin A. It also contains small amounts of iron and vitamin C.

Leaf lettuce (L. sativa var. crispa)
Also known as Looseleaf, Bunching, or Cutting Lettuce, this Lettuce does not form a head. It has loosely bunched leaves connected to a stem. The leaves are tender, delicate, and mildly flavored. Leaf Lettuces comprise Oak Leaf and Lollo Rosso Lettuces. Leaf lettuce comes in varying colors (greens and reddish purples) and differing leaf shapes. Among them is the Red Leaf Lettuce which has a crispy texture and a mild, earthy flavor. A cup of Red Leaf Lettuce contains 42% of your daily needs in vitamin A and small amounts of vitamin C and iron. Leaf Lettuces are used mainly for salads.

Romaine lettuce (L. sativa var. longifolia)
Romaine Lettuce, or Cos Lettuce, is another type frequently sold in grocery stores. Used mainly for salads and sandwiches, Romaine Lettuce features long, sturdy dark green leaves with firm ribs down their centers, with a strong flavor. It is a key ingredient in the preparation of Caesar salads. A cup of chopped Romaine lettuce contains 82% of your daily needs in vitamin A. It also contains some iron, calcium, and vitamin C. Unlike most other Lettuces, it tolerates heat and may also be cooked.

Celtuce Lettuce (L. sativa var. augustana)
Celtuce Lettuce, also called Asparagus Lettuce, Stem Lettuce, or Chinese Lettuce, is grown primarily for its thick stems rather than its leaves. Popular in Asian cooking, Chinese principally, the crisp and moist stems have a mild but nutty, sometimes almost smoky, flavor. They can be eaten in salads or cooked, grilled, roasted, or stir-fried. Celtuce is a very good source of Vitamins A, C, B-9 (Folate), and manganese. It also provides calcium, copper, non-heme iron, magnesium, phosphorus, potassium, selenium, and zinc.

Lettuce Health Benefits

• While Lettuce is famous for giving salads their base, it can also provide some health benefits.
• The health benefits of Lettuce come mostly from its vitamin levels and vary depending on the type of Lettuce.
• Lettuce is a great source of vitamin K. One cup provides about 40% of your daily needs. Vitamin K helps strengthen bones.
• Lettuce is also a source of vitamin A, which plays a role in eye health. Vitamin A can reduce a person’s risk of cataracts. Vitamin A also helps prevent macular degeneration.
• Lettuce contains small amounts of vitamin C and iron.
• Lettuce is low in calories and about 95% water: it is particularly effective at promoting hydration and perfect for people who want to lose weight.

Growing Lettuce

• Lettuce grows up to 6-12 in. tall and wide (15-30 cm), depending on the variety.
• Lettuce performs best in full sun to part shade in fertile, loose, consistently moist, but well-drained soils. Leaves appreciate some light shade in the heat of the day. The optimal pH ranges from 6.0-6.7.
• To grow tender, trouble-free Lettuce, keep the soil moist but not soggy.
• Depending on the variety, Lettuces take 30-70 days to harvest.
• Lettuce needs to grow rapidly and without interruption.
• Lettuce grows best in the cool weather of the spring and fall when temperatures are between 60-65°F (15-18°C).
• Lettuce will tolerate a low temperature of 45°F (7°C) and grow poorly above 75°F (24°C).
• High temperatures (70-80°F or 21-26°C) and dry soil can trigger Lettuces to bolt and flower, turning the leaves bitter and stopping leaf production.
• Prevent bolting by providing plants with partial shade in summer heat, harvesting promptly, and planting bolt-resistant cultivars.
• Sow seeds in the ground 2-4 weeks before your last spring frost date or as soon as the soil temperature is between 45-65°F (7-18°C).
• Plant additional seeds every 2 weeks for a continuous supply during the growing season.
• Avoid planting Lettuce in soil where it has been grown within the last 3 years.
• In most areas, it is possible to plant another Lettuce crop in the fall or even early winter.
• Plant seeds 1/2 inch deep (1.3 cm) in rows 12 inches (30 cm) apart.
• Thin seedlings when the first true leaves appear and continue until the plants are 12 inches (30 cm) apart. You can add the seedlings to your salads.
• Mulch to retain moisture, keep soil temperatures cool, and control weeds.
• Provide plenty of nitrogen in both quicker-release forms, such as blood meal or soybean meal, and slower-release forms, such as compost or alfalfa meal.
• Fertilize 3 weeks after transplanting.
• Lettuce has shallow roots; if the plants dry out, they will turn bitter earlier in the season.
• Harvest Lettuce in the morning when a firm heart has formed. Cut through the stem at the base of the plant.
• Loose-leaf varieties can be harvested when the leaves are large enough to be worth eating.
• Lettuce is susceptible to various pests. Keep an eye out for aphids, lettuce root aphids, cutworms, leafminers, slugs, and snails.
• Lettuce is susceptible to various diseases, including gray mold or botrytis and lettuce downy mildew, cucumber mosaic virus, lettuce leaf drop, and lettuce mosaic virus.
• Lettuce is propagated by seed.

Good Companion Plants for Lettuce

Here are good companion plants for lettuce and the reason why they are good for lettuce:

• Alyssum:  Alyssum produces small white flowers that attract beneficial insects, such as hoverflies and lacewings, which can help to control aphids and other pests that may damage lettuce.
• Basil: is thought to improve the flavor and growth of lettuce.
• Beets: Beets and lettuce have different root depths, so they don’t compete for the same nutrients in the soil. In fact, beets can help to improve soil health by breaking up compacted soil and adding organic matter.
• Calendula: Calendula is a trap crop that will attract any aphids the beneficial insects miss and give the pests a more enticing meal than the Lettuce.
• Chamomile: Chamomile is a good companion plant for lettuce because it attracts beneficial insects, such as parasitic wasps and hoverflies, which eat aphids.
• Chervil: Chervil is a great slug repellant and will prevent your lettuce to be devoured by slugs.
• Chives and Garlic: Both are good companion plants for lettuce because they help to deter pests, such as aphids.
• Cilantro: Cilantro is a good companion plant for lettuce because it attracts beneficial insects, such as parasitic wasps and hoverflies, which eat aphids.
• Carrots: Carrots are good companion plants for lettuce because they help to loosen the soil and attract beneficial insects, such as ladybugs and lacewings, which eat aphids.
• Dill: Dill is a good companion plant for lettuce because it attracts beneficial insects, such as ladybugs and lacewings, which eat aphids. It improves the health and growth of Lettuce.
• Marigolds: Marigolds are good companion plants for lettuce because they help to deter pests, such as nematodes and aphids, and can help to improve soil health. They can also be a trap crop for slugs: plant them close to Lettuce to keep them safe.
• Nasturtiums : Nasturtiums are good companion plants for lettuce because they attract beneficial insects, such as predatory mites and parasitic wasps, and deter insect pests, such as the infamous beetles and aphids.
• Onions and Shallots: Onions are good companion plants for lettuce because they help to deter pests, such as aphids, and they discourage rabbits. They also have different root depths, so they don’t compete for the same nutrients in the soil.
• Parsnips. Parsnips and lettuce have different root depths, which means they don’t compete for the same nutrients in the soil. This can help to improve soil health and ensure that both plants have access to the necessary nutrients for growth.
• Peas: Peas are legumes, which means they can fix nitrogen from the air and add it to the soil. This can help to improve soil health and provide the necessary nutrients for the growth and development of lettuce. They also grow tall and can provide shade for lettuce, which can help to protect it from the hot sun during the summer months.
• Poached egg plant: Poached egg plant produces small, delicate flowers that are highly attractive to a range of beneficial insects, such as hoverflies, lacewings, and parasitic wasps, which can help to control aphids and other pests that may damage lettuce.
• Radishes: Radishes are good companion plants for lettuce because they help to break up compacted soil. When grown with Lettuce, they are more tender and succulent.
• Strawberries: Strawberries are good companion plants for lettuce because they help to improve soil health and attract beneficial insects, such as predatory mites and parasitic wasps.
• Turnips: Turnips have a deep root system that can help to break up compacted soil and add organic matter to the soil. Additionally, they can help to deter pests that can damage lettuce, such as aphids and flea beetles.

Bad Companion Plants for Lettuce

While there are many good companion plants for lettuce, there are also some plants that can have a negative impact on its growth and yield. Here are some bad companion plants for lettuce:

• Cabbages and other brassicas: Cabbages, broccoli, brussels sprouts, cauliflower, kale, or kohlrabi can be bad companion plants for lettuce because they require similar nutrients from the soil, which can lead to competition and reduced yield. Additionally, some brassicas, such as mustard and rapeseed, produce chemicals that can inhibit the growth of other plants, including lettuce.
• Fennel: Fennel is known to inhibit the growth of many plants, including lettuce. It secretes a chemical called anethole that can stunt the growth of nearby plants.
• Celery: Celery can be a bad companion plant for lettuce because it can attract the same pests and diseases, including aphids and whiteflies. Planting them together can increase the risk of pest infestations, damaging both crops.
• Parsley: Parsley causes lettuce to bolt, meaning it will go to seed much sooner than it would otherwise.