They also contain Lactucarium, a very opium-like substance that is known to induce sleep, but to get that effect, one needs to eat lots of lettuce! Its name has been derived from the Latin word lac, which means milk, in reference to the plant's milky juice.
Lettuce produces many small dandelions lookalike flower heads. The types or cultivars include butterhead, Chinese lettuce, iceberg (crisphead), Romaine (cos), etc. Certain cultivars were introduced to remove the bitterness from their leaves.
This is done by adding more water content to the variety. However, lettuce that is high on water content has very little nutrient value, whereas the bitter or darker ones contain a high level of antioxidants.
Use sowing medium that is moist, yet not water retaining, and has a good composition of organic compost. Sprinkle seeds five inches apart in rows spaced out by four inches. Mist the sowing mixture regularly until you see the seeds sprout. Once the seedlings begin to appear, acclimatize the container to more sunlight. Sow seeds in spring or early summer.
Planting and Watering
Once seedlings have developed strong roots and shoots, about six true leaves, you can thin them out. Prepare the garden area or container before you begin to transplant. This will ensure that the roots aren't exposed for a long duration. Lettuce should be planted 2-4 weeks before the last frost date, and/or about 6 to 8 weeks before the first frost date.
Select a location that receives at least 5 or more hours of sunlight a day. Till the soil well to make a vegetable patch. Growing lettuce in raised bed vegetable gardens will also produce good results. Add a good quality organic compost and some fertilizer to the soil. Plant each seedling about four to six inches apart in rows spaced out by four inches.
Water the lettuce well, although they need a good level of moisture, as the roots are shallow. However, don't over water them. Excess water will rot the roots, while less water will stunt their growth and make the leaves bitter.
If lettuce is planted in soil that has been well fed with rich organic compost, fertilization is not needed. Appropriate quantity (as per package directions) and timing (just once in its entire growing season) will ensure a good harvest. As it is a green vegetable, pest attack is unavoidable.
Being voracious eaters, caterpillars, cabbage worms, loopers, aphids, and armyworms can destroy the entire crop. Diseases like anthracnose, bolting, damping off, mildew, viruses, and leaf spots too can damage the plant.
Head lettuce is harvested when the head gets firm, the leaf lettuce should be harvested when leaves have just opened up from its loose head. One must ensure that it is harvested before it begins to bolt. Bolting is formation of flowers and seeds due to high temperatures which makes the leaves bitter. To get a steady flow of lettuce, plant them in succession.