Lettuce cultivation
Lettuces grown in the ground require frequent watering and repeated hoeing to promote water penetration and limit the proliferation of weeds. They can be sown directly in the garden in rows spaced 30 to 50cm apart. In this case, the rows are thinned when the plants have four to five leaves; make a good salad with the leaves of the sacrificed plants!
Lettuces sown indoors in boxes are transplanted into the ground 25-30 cm apart when they have four to five leaves. When transplanting, be careful not to bury the collar or to tighten it too much, then water at the neck to help the soil adhere well to the roots and thus promote recovery.
Because they do not form heads, leaf lettuces can be grown in any good, well-worked soil enriched with compost, even soil rich in nitrogen. In poor soil, they go to seed much more quickly. Choose a well-exposed site that will thaw quickly and prepare the soil the previous fall. You will be able to plant very early in spring and enjoy the best leaf lettuce there is from May to September. Some of these lettuces do not tolerate heat well, resulting in tough leaves with a bitter taste; These varieties grow very quickly and are perfect for growing in spring and autumn.
Head lettuce likes balanced and fairly rich soil. If the nitrogen content is higher than that of phosphorus and potash, the outer foliage will take over the apple, which will form poorly and remain soft. Unlike leaf lettuces, these lettuces are not suitable for muck soils, unless potash and phosphorus are incorporated to obtain a better balance between the three major mineral elements.
Romaine lettuce is an excellent choice for summer growing because it tolerates heat well. Since its head forms slowly, we can help it by tying it two-thirds of its height with a sprig of rye or a piece of raffia to speed up the whitening of the leaves. To avoid the appearance of rot in the core of the apple, proceed in very dry weather.
Forcing lettuces
All lettuces can be forced, that is, sown indoors before the end of winter to be put in the ground at the young plant stage. They can also be grown in layers (plastic tunnels or low shelters on the ground and covered with glazing) directly in the ground.
- Leaf and romaine lettuces give best results in warm layers* where the temperature is gradually increased from 15 to 23°C.
- Head lettuces prefer cold layers.
*The “heating” of a warm bed comes from heating mats, hot water pipes in the ground or a manure base. In this case, the heating is regulated by opening the shelter frames more or less wide.
Nutritious intake of lettuce
Whether romaine, leaf or head, lettuce contains few calories and a lot of water (around 95%).
However, its intake of vitamins and nutrients varies from one group to another:
- Vitamin A: leaf lettuce (excellent source)
- Vitamin B9: romaine lettuce (good source); head and leaf lettuce (source)
- Vitamin C: romaine and leaf lettuces (source)
- Vitamin K: romaine, leaf and head lettuce (excellent source); head lettuce (good source)
Potassium, calcium, magnesium, phosphorus, sodium, manganese: source
Did you know that…
✤ The antioxidants contained in lettuce are better absorbed by the body when they are accompanied by fat. A drizzle of olive oil or a handful of nuts makes all the difference!
✤ Eating lettuce several times a week reduces the risk of lung cancer.
✤ More particularly in romaine lettuce, certain compounds have a neuroprotective effect and help prevent degenerative diseases such as Alzheimer's.
✤ The greatest quantities of antioxidants are found in leaf lettuces and red lettuces contain more than their green equivalent. They are followed, in descending order, by romaines, butter potatoes and batavias.
✤ Romaine lettuce wins the prize for the highest level of soluble fiber, followed by leaf and head lettuces.
