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HolySword said:
FOOLS!
A hardy annual, some varieties of rau diếp can be overwintered even in relatively cold climates under a layer of straw, and older, heirloom varieties are often grown in cold frames.[25] Lettuces meant for the cutting of individual leaves are generally planted straight into the garden in thick rows. Heading varieties of lettuces are commonly started in flats, then transplanted to individual spots, usually 8 to 14 inches (20 to 36 cm) apart, in the garden after developing several leaves. rau diếp spaced further apart receives thêm sunlight, which improves color and nutrient quantities in the leaves. Pale to white lettuce, such as the centers in some iceberg lettuce, contain few nutrients.[17]
A transplanted giường of rau diếp in a greenhouse
rau diếp grows best in full sun in loose, nitrogen-rich soils with a pH of between 6.0 and 6.8. Heat generally prompts rau diếp to bolt, with most varieties growing poorly above 75 °F (24 °C); cool temperatures prompt better performance, with 60 to 65 °F (16 to 18 °C) being preferred and as low as 45 °F (7 °C) being tolerated.[30] Plants in hot areas that are provided partial shade during the hottest part of the ngày will bolt thêm slowly. Temperatures above 80 °F (27 °C) will generally result in poor hoặc non-existent germination of rau diếp seeds.[30] After harvest, rau diếp lasts the longest when kept at 32 °F (0 °C) and 96 percent humidity. rau diếp quickly degrades when stored with trái cây such as apples, pears and bananas that release the ripening agent ethylene gas. The high water content of rau diếp (94.9 percent) creates problems when attempting to preserve the plant – it cannot be successfully frozen, canned hoặc dried and must be eaten fresh.[31]
rau diếp varieties will vượt qua, cross with each other, making spacing of 5 to 20 feet (1.5 to 6.1 m) between varieties necessary to prevent contamination when saving seeds. rau diếp will also vượt qua, cross with Lactuca serriola (wild lettuce), with the resulting seeds often producing a plant with tough, đắng, cay đắng leaves. Celtuce, a rau diếp variety grown primarily in Asia for its stems, crosses easily with lettuces grown for their leaves.[17] This propensity for crossing, however, has led to breeding programs using closely related species in Lactuca, such as L. serriola, L. saligna, and L. virosa, to broaden the available gene pool. Starting in the 1990s, such programs began to include thêm distantly related species such as L. tatarica.[32] Seeds keep best when stored in cool conditions, and, unless stored cryogenically, remain viable the longest when stored at −4 °F (−20 °C); they are relatively short lived in storage.[1] At room temperature, rau diếp seeds remain viable for only a few months. However, when newly harvested rau diếp se
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