Lettuce (Lactuca sativa), is an annual plant that belongs to the Asteraceae family. It mainly grows as a leaf vegetable and it is well known as one of the most essential ingredients in plenty of salads. Lettuce is widely known for its colourful leaves, with red and green being the most usual among them. Colour usually depends on the type of lettuce that we decided to grow. Some varieties may have yellow or gold coloured leaves. There are several types of lettuce that grow all over the world, but the most common are the following.
- Leaf Green. The widely-known variety. It has bundled leaves and it is mainly used for salads. It has a white, crisp head.
- Romaine / Cos. This variety has large and long leaves. It has more leaves than Leaf Green and its head is white around its center. People often use this type of lettuce in various salads (Caesar Salad).
- Butterhead. This variety has broad leaves. Its name is derived from its sweet flavor (tastes like butter).
- Crisphead / Iceberg. This variety is mostly grown in Europe. It can grow and thrive in the United States too. It is vulnerable to heat. It is also known as cabbage lettuce because of its short and flat head.
- Celtuce and Oilseed. Some varieties are not grown for their leaves. Celtuce is a variety that mainly grows in China and people use it for its stem. Oilseed is a variety easily recognised by the small number of leaves.
Lettuce is a plant that needs cool weather to grow fast and mature quickly without bolting (producing seeds). The seeds are genetically programmed to go dormant above a certain temperature. The ideal temperature is between 45 and 64 °F (7-18 °C). It generally takes 65 to 130 days from planting to harvesting. However, this depends on the variety that we grow and the time of the year we choose to plant it. Its height can reach 12 inches (30 cm). The plant has a shallow root system and thus it needs smaller and more frequent irrigation sessions in order to give a good yield.
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