Lettuce is easy to grow and has a wide variety of flavor types to choose from. Lettuce can be grown in all hardiness zones, and can planted in both the spring and fall. Lettuce thrives in cooler temperatures, desiring full sun in cool weather and light shade in warmer weather. The plant grows in most soils, though prefers rich, well-drained soil. Optimum temperatures are between 60 to 65 F. If the temperature raises above 80 F the plant will bolt, or go to seed) and leaves will turn bitter, which is why shade is important for hotter regions. Directly sow seeds into the soil near the surface, as seeds require sunlight to germinate. Seeds can be replanted every 15-20 days in summer and 10-15 days in winter for a steady supply of leaves. Lettuce requires a constant supply of moisture and has a shallow root system, so take care when weeding and harvesting leaves. Bitter leaves are an indication of excess heat, over or under watering, and overmaturity. Soil should maintain a moist state but not be over watered, which can cause rotting. Water lettuce in the morning in order for leaves to dry and avoid disease by evening. Leaf lettuce takes 40 days from seed to harvest, and head lettuce 70 days.
Lettuce is a crafty option for growing in containers, and is especially useful in small, urban spaces (1). Lettuce generally remains pest-free, although snails and slugs hide under the cover of darkness and chew leaves, weakening the plant. Keep leaves dry in order to prevent powdery mildew and fungal infections (4). The name Lactuca sativa is derived from the “lactis,” meaning milk. The reference to milk is due to the bitter white sap contained within the stem and thick veins of the plant (10).
Three primary varieties of lettuce are butterhead, cos (Romaine), and looseleaf. Butterhead lettuces form loose, open heads, and get their name from their butter-like “melt in your mouth” consistency. Looseleaf lettuces are multicolored, fast and easy to grow. Cos (Romaine) varieties have a crunchy spine, stronger leaves, stronger flavor and form upward heads (2). Iceberg lettuce forms a tight, cabbage-like head, and grows best in cool weather. Harvest when heads are fully formed and firm before temperatures reach 75 F in order to avoid bolting and resulting bitterness. Iceberg has a mild taste and slight crunch, and is often used as base for salads (4). Arugula, also known as rocket, roquette, rugula and rucola (16), grows in thin leaves and has a distinctive, spicy flavor (3). The plant grows larger than greens like lettuce, reaching up to 3 feet in height. Unlike other varieties of lettuce, arugula grows best in full sun. When hot outside, water more often to avoid bolting. If plants go to seed in heat, seeds can be replanted in the fall. Arugula is rarely disturbed by pests due to its intense flavor. Pick arugula leaves when they are smaller and young, as large leaves are too tough and bitter.
Mustard greens have a peppery taste, similar to that of radish roots. Smaller greens are used for salads, and can be eaten both raw and cooked. Larger leaves are much spicier, and lessen in spice when cooked. There are several varieties of Mustard Greens, such as the Chinese Green Choi Sum. Colors range from shades of green to red and purple (5). Sorrel has a distinctive, lemony flavor that tastes best in early spring, which is the traditional season for sorrel soup (6). The lemony flavor of sorrel is due to its oxalic acid content, which, although harmless in small amounts, is best to be avoided by those with kidney stones. Sorrel has three main varieties: Garden Sorrel, French Sorrel, and Blood Sorrel. Both Garden and French varieties can become invasive unless precaution is taken against reseeding. When bolting occurs, clip off the seed-filled heads when green. Sorrel is related to the weed called yellow dock, which also has the characteristic of profuse reseeding. Blood sorrel can be used as a beautiful ornamental plant. Blood sorrel leaves are only edible when young (6). Sorrel can be blanched and cooked to remove its toxicity.
Culinary and Medicinal Uses
Lettuce is arguably the most versatile ingredient, and is, of course, the main ingredient in most salads. Salads can also be decked out limitlessly with nuts, fruit, seeds, vegetables, meat, cheese and sprouts. However, fresh lettuce leaves require no more than a simple vinaigrette, which can be made with vinegar, oil and other flavorings such as lemon juice, mustard and honey, to name a few. Romaine lettuce is the key ingredient in Ceasar salad. Arugula is usually used as an accompaniment leaf in salads, due to its sharp flavor (3). Arugula can be added to sauces and pasta dishes as flavoring (7). Arugula combines deliciously in salad with goat cheese, walnuts and beets. Goat cheese is commonly added to salads, especially those with bitter greens like mesclun. Sturdier leaves, like romaine and iceberg, can be used to make lettuce wraps (8). Romaine can be lightly coated with olive oil and grilled. Serve with dressing. Lettuce soup is a unique use for the green, and unlike salad improves with flavor as it sits. Soup can be served hot or cold (9). Sorrel pairs deliciously with fish and shellfish, such as salmon with sorrel sauce. Lettuce is composed of almost 95% water, and is highly recommended for those with obesity and diabetes, as it is a low carbohydrate and low calorie content. The plant contains a rich store of iron and potassium, as well as Vitamins A, B and C. Lettuce is recommended for relief of constipation, due to its fiber content. Lettuce is a healthy choice for those with diabetes, as it is a low carbohydrate vegetable. Salad is often eaten before meals, as it tones the stomach and prepares the system for digestion. Lettuce strengthens the nervous system, and promotes a mild sedative effect when eaten regularly. It also contains large amounts of vitamin B, which is necessary for a healthy functioning nervous system. The plant contains a substance known for its sleep-inducing properties, and is recommended for insomnia. Eating a food or drink containing vitamin C in combination with lettuce magnifies the absorption of iron. Iceberg contains a high amount of water and fewer nutrients than most other varieties (13).
Significance to Cultural Communities
In Chinese culture, stir-fried iceberg lettuce, and lettuce in general, is considered good luck and is served on special occasions such as birthdays and New Years (10). In Egyptian culture the lettuce seeds are ground for oil, and the Ancient Egyptians considered lettuce a medicine for male fertility. (11). In ancient cultures lettuce was revered as both an appetite stimulant and sleep aid. Sorrel soup (Green Borscht) is a spring delicacy in Eastern European cuisine. The French version of Green Borscht is souped up (!) with cream and butter, which mellow out the soup’s sharp flavor. Sorrel is used in Vietnamese dishes such as soups and spring rolls. In Germany, sorrel is made into a green sauce and used as a condiment (12). Arugula is popular in Italian cuisine. A typical Romanian salad is comprised of romaine, arugula, chicory, mallow and lavender, and topped with a “cheese sauce for lettuce (16).
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- "Lettuce Varieties, Types of Lettuce, Varieties of Lettuce." Grow It Organically. N.p., n.d. Web. 07 Oct. 2014. <http://www.grow-it-organically.com/lettuce-varieties.html>.
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- "Growing Tips for Iceberg Lettuce." Home Guides. N.p., n.d. Web. 07 Oct. 2014. <http://homeguides.sfgate.com/growing-tips-iceberg-lettuce-26825.html>.
- "How to Grow Mustard Greens." Backyard Gardening Blog |. N.p., n.d. Web. 07 Oct. 2014. <http://www.gardeningblog.net/how-to-grow/mustard-greens/>.
- "All About Growing Sorrel." Mother Earth News. N.p., n.d. Web. 07 Oct. 2014. <http://www.motherearthnews.com/organic-gardening/growing-sorrel-zw0z1312zsto.aspx#axzz3F0aAjsAv>.
- "Cooking Ingredients: Lettuce." Cooking Ingredients: Lettuce. N.p., n.d. Web. 07 Oct. 2014. <http://www.dlc.fi/~marian1/gourmet/i_lettuc.htm>.
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- "The Crisper Whisperer: 4 Ways to Use Lettuce (Other Than Salad)."Serious Eats: The Destination for Delicious. N.p., n.d. Web. 07 Oct. 2014. <http://www.seriouseats.com/recipes/2010/06/how-to-cook-what-to-do-with-lettuce-soup-grilled-stir-fried-lettuce-sauce-recipes.html>.
- "Romaine Lettuce." The World's Healthiest Foods. George Mateljan Foundation, n.d. Web. 07 Oct. 2014. <http://www.whfoods.com/genpage.php?tname=foodspice&dbid=61>
- "Lettuce Health Benefits, Medicinal Uses and Properties." Foods and Diseases. N.p., n.d. Web. 07 Oct. 2014. <http://foodsanddiseases.com/lettuce-health-benefits-medicinal-uses-and-properties-2/>
- "The History of Lettuce." Food History. N.p., n.d. Web. 07 Oct. 2014. <http://kitchenproject.com/history/Salads_Lettuce/Lettuce/index.htm>.
- "Lettuce - Lactuca Sativa- Daisy Family." Lettuce. N.p., n.d. Web. 07 Oct. 2014. <http://www.selfsufficientish.com/lettuce.htm>.
- "The History of Lettuce and the Healthiest Greens." New Food Culture. Web. 07 Oct. 2014. <http://www.newfoodculture.com/2014/07/23/the-history-of-lettuce-and-the-healthiest-greens/>.
- "Real Food Right Now and How to Cook It: Sorrel." EcoCentric. Grace Communications Foundation, Web. 07 Oct. 2014. <http://www.gracelinks.org/blog/2374/real-food-right-now-and-how-to-cook-it-sorrel>.
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