Lettuce. Lactuca sativa, Aster, Daisy, Composite, Sunflower Family ( Asteraceae ), ( Compositae ), Commonly Known As: Lettuce. We wish to thank Wikipedia, the free encyclopedia for some of the information, and images on our page. We share information, images, and donate to Wikipedia. Lettuce (Lactuca sativa) is an annual plant of the daisy family Asteraceae. It is most often grown as a leaf vegetable, but sometimes for its stem and seeds. Lettuce was first cultivated by the ancient Egyptians who turned it from a weed, whose seeds were used to produce oil, into a food plant grown for its succulent leaves. Lettuce spread to the Greeks and Romans. By 50 AD, multiple types were described, and lettuce appeared often in medieval writings, including several herbals. During the 16th through 18th centuries many varieties were developed in Europe, and by the mid-18th century cultivars were described that can still be found in gardens. Europe and North America originally dominated the market for lettuce, but by the late 20th century the consumption of lettuce had spread throughout the world. Lettuce is generally grown as a hardy annual, lettuce is easily cultivated, although it requires relatively low temperatures to prevent it from flowering quickly. It can be plagued with numerous nutrient deficiencies, as well as insect and mammal pests and fungal and bacterial diseases. L. sativa crosses easily within the species and with some other species within the Lactuca genus; although this trait can be a problem to home gardeners who attempt to save seeds. Generally grown as a hardy annual, lettuce is easily cultivated, although it requires relatively low temperatures to prevent it from flowering quickly. It can be plagued with numerous nutrient deficiencies, as well as insect and mammal pests and fungal and bacterial diseases. L. sativa crosses easily within the species and with some other species within the Lactuca genus; although this trait can be a problem to home gardeners who attempt to save seeds. Lettuce is most often used for salads, although it is also seen in other kinds of food, such as soups, sandwiches and wraps; it can also be grilled. One variety, the asparagus lettuce, is grown for its stems, which are eaten either raw or cooked. Lettuce is a rich source of vitamin K and vitamin A, and is a moderate source of folate and iron. Contaminated lettuce is often a source of bacterial, viral and parasitic outbreaks in humans, including E. coli and Salmonella. In addition to its main use as a leafy green, it has also gathered religious and medicinal significance over centuries of human consumption. Here Are Some Of The More Popular Types Of Lettuce: Buttercrunch Lettuce: A compact butterhead-type head lettuce is productive, heat tolerant and slow to bolt. Mildly flavored leaves. 65 DAYS. Romaine Lettuce: Piquant flavor sets this Paris White Cos head lettuce apart from the other lettuces. Produces vase-shaped heads. 10 in. tall. 70 DAYS. Black Seeded Simpson Lettuce: Black Seeded Simpson was one of the first lettuce varieties to be deemed an 'heirloom' in the middle years of the 19th century. This looseleaf variety is also one of the fastest lettuces to maturity, completing its growth cycle within 45-60 days. Iceburg Lettuce: Introduced in 1894, it has crisp firm leaves grow in compact, medium-sized heads. Light green fringed and heavily ruffled outer leaves with hearts that blanch to silvery white. Grows best in cool weather. The classic crisphead lettuce. Ready to harvest 85 days after sowing seeds. Decide on the site for your lettuce some months in advance of planting. 1. Determine the last expected spring frost date for your area. Plan to plant your lettuce 2 or 3 weeks before the last frost-free date. 2. Cultivate your planting area to break up any hard soil, keeping your rows about 12 to 24 inches apart. Lettuce varieties prefer well-draining, loose soils with plenty of organic matter. 3. If a soil test has not been taken, make a preplant application of 5-10-10 at the rate of 3 pounds per 100 square feet. Use a starter solution for transplants, and sidedress cautiously after the first leaves reach about the size of a dime using three tablespoons of 33-0-0 per 10 feet of row). Sidedress cautiously until a large number of lettuce are set. Too much nitrogen before fruit set causes all foliage and no fruit. After fruit set, fertilize regularly using a complete fertilizer. Soil pH should be 5.8 to 6.5 for best growth. 4. Purchase certified lettuce seed from your local garden center or nursery. 5. Lettuce should be spaced 1/8 to 3/8 inches deep, � inch apart, in rows 12 to 24 inches apart. Select a well-drained, loamy or sandy loam soil for planting. Avoid areas that have had eggplant, tobacco, pepper or Irish potato planted in the previous year. 6. Apply a layer of organic mulch to help maintain soil temperatures and to prevent weeds from growing. 7. Water your lettuce once or twice a week when the soil feels dry to the touch. Do Not Spray Water On Your Plants.Lettuce has shallow root systems so they only need a light watering to maintain constant soil moisture. Water sufficiently to moisten the soil to a depth of at least 6 inches. The critical period for moisture is during fruit set and fruit development. Mulching can help to provide uniform moisture, conserve water and reduce weeds. 8. Monitor your lettuce for disease and pest problems.Lettuce grown by spraying water in Arizona, often suffer from fungal diseases, which can be treated with a fungicide. Control common pests such as snails, potato tubermoth and aphids by sprinkling nontoxic diatomaceous earth around the affected Pepper plants. 9. Lettuce should be ready for harvest in about 65 to 85 days from seed. Some varieties can take up to 160 days. Reduce disease problems by: �Rotating planting locations. Don't plant peppers, eggplants and related crops in the same garden spot more often than once every three years. �Removing all plant debris from the garden each year. Eliminate any volunteer lettuce that may occur between crops. Pests Of Lettuce In Arizona: Insects: Crickets & Beetles, Saltmarsh Caterpillar, Sweetpotato Whitefly, Leafminers, Beet Armyworm, Cabbage Looper, Corn Earworm, Tobacco Budworm, Green Peach Aphid, & Thrips. Apply a Bacillus thuringiensis (Bt) based insecticide to control them. Diseases: Diseases may be a problem especially during cool, wet weather. A variety of viruses attack lettuce and each produces symptoms characteristic of the particular virus species such as leaves mottled with yellow spots, and knotted or forked roots. Some of the more common diseases of lettuce in Arizona include bottom rot caused by Rhizoctonia solani, leaf drop caused by Sclerotinia minor and S. sclerotiorum, downy mildew caused by Bremia lactucae and powdery mildew caused by Erysiphe cichoracearum. Another major disease of lettuce in Arizona is big vein, which is caused by double-stranded ribonucleic acid that is presumed to be a virus-like agent. Fungicides can be effective management tools for lettuce diseases caused by fungi. Treat with an approved fungicide. Neem oil, sulfur, and other fungicides can be used. Beneficial Insects Of Lettuce In Arizona: Not all insects found in our gardens, & orchards are pests. Many organisms benefit the grower by eating or parasitizing pests in the orchard. These organisms are known as beneficials, natural enemies, or biological control agents. They may be native or introduced from other areas. Beneficial natural enemies (insects and mites) that may occur in our gardens, & orchards could be classified as predators or parasitoids. Predators are those that attack, kill, and feed directly on a pest (prey). Examples of common garden, or orchard predators are ladybeetles, flies, lacewings, wasps, bugs, ants, spiders, and predator mites. Parasitoids are insects that lay eggs on or in a pest (host). The developing larva lives and feeds on the host, parasitizing and eventually killing it. Examples include parasitic wasps such as the egg parasite, Trichogramma sp. Bees are a different class of beneficial insects in the garden or orchard in that they benefit the grower by aiding pollination. It is important that growers are able to recognize, identify, and conserve beneficials in their gardens, & orchards. Conservation of beneficial organisms is a basic tenet of an ecologically sound pest management strategy. Conservation or enhancement of beneficials can be achieved through judicious use of pesticides such as spraying only when and where needed, accurate timing of sprays, and selecting pesticides that are least toxic to beneficials. For Example: Many growers now place colonies of the Blue Orchard Mason bees in their orchards to pollinate their crops for maximum production. Quick Notes: Type: The most commonly eaten part of lettuce are the leaves. Some are grown for taproot or stems. Height: About � - 2 feet tall. Lactuca sativa is an annual glabrous herb with a thin tap root and an erect stem 30�100 cm tall, branched in the upper part. Spread: About � - 2 feet wide. Flowers: An inflorescence (capitulum, head) is composed of 7�15 (35) yellow ligules (florets). The heads form a corymbose, densely bracted panicle. Anthocyanin can be distributed on the cotyledons and true leaves, stems and ligules. The involucre is 10�15 mm long, cylindrical; involucral bracts are broadly to narrow lanceolate, light green, with white margins, erect at the stage of fruit maturity. Blooming Time: Spring through Fall. Fruit: The fruit (achene) has 5 to 7 setose ribs on each side, a beak and a white pappus. Its length (including beak) is 6�8 mm, and its color is white, cream, gray, brown or black. Leaves: Blue-green to dark-green in color, pirally arranged, forming a dense rosette or a head before bolting. Their shape is oblong to transverse elliptic, orbicular to triangular, undivided to pinnatisect. The leaf margin is entire to setose dentate, often curly. Stem leaves are oblong elliptic, with a cordate base. Elevation: 0 - 5,500 feet. Some can grow up to 10,000 feet, but you need to time planting with frosts. Hardiness: USDA Zone 3a: to -39.9 �C (-40 �F) USDA Zone 3b: to -37.2 �C (-35 �F) USDA Zone 4a: to -34.4 �C (-30 �F) USDA Zone 4b: to -31.6 �C (-25 �F) USDA Zone 5a: to -28.8 �C (-20 �F) USDA Zone 5b: to -26.1 �C (-15 �F) USDA Zone 6a: to -23.3 �C (-10 �F) USDA Zone 6b: to -20.5 �C (-5 �F) USDA Zone 7a: to -17.7 �C (0 �F) USDA Zone 7b: to -14.9 �C (5 �F) USDA Zone 8a: to -12.2 �C (10 �F) USDA Zone 8b: to -9.4 �C (15 �F) USDA Zone 9a: to -6.6 �C (20 �F) Soil pH requirements: Ideal Is 5.8 to 6.6. The yield is low at pH below 5 or above 7. 5.6 to 6.0 (acidic) 6.1 to 6.5 (mildly acidic) 6.6 to 7.5 (neutral) 7.6 to 7.8 (mildly alkaline) Light: Full Sun to Partial Shade. Habitat: Mulched areas. Well-drained soil with a 5.8 to 6.6 pH. Native: Lettuce was first cultivated by the ancient Egyptians who turned it from a weed, whose seeds were used to produce oil, into a food plant grown for its succulent leaves. Miscellaneous:

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