Head lettuce (Lactuca sativa var. capitata)
The head lettuce belongs to the complex family (Compositae). Her homeland is the Mediterranean and Asia Minor. It was known as a vegetable in ancient Egypt, and also in medieval Europe. The different varieties of lettuce have specific light and heat requirements, which is why a distinction is made between spring cultivation, summer and autumn. For spring and autumn cultivation, you need to choose the so-called varieties. day long, which in the summer, with a long day and high temperature, prematurely knock out the inflorescence shoots. Varieties that are indifferent to the length of the day are suitable for summer cultivation, forming relatively durable, compact heads. In March, seeds of early ground varieties are sown for a cold inspection, e.g.. varieties of 'Queen of May'. In April, the plants are planted into the ground.
To maintain the continuity of the lettuce harvest, seeds are sown at intervals of two- or three-week-olds. From May to July, it is best to grow crisp lettuce varieties, which is unresponsive to the length of the day. Two varieties are cultivated in Poland: ‘Golden State D’ oraz Vanguard. From mid-August to mid-September, winter lettuce is sown and planted, e.g.. a variation of 'Winter Nansen'. Areas with a mild climate are best suited for this, sheltered from the wind. In winter, the plants should be covered with spruce twigs.
In any case, direct seeding into the ground and subsequent abortion is preferable to seedling production and replanting. Lettuce sown directly into the ground does not strike the inflorescence shoots, and an undamaged tap root develops normally, making the heads fuller and more delicate, which offsets the higher seed consumption and the effort to break seedlings. Under the glass, the plants are grown at a distance between them 25 x 25 cm, and in field crops 30 x 25 cm. Brittle lettuce is better to grow a little less - 30 x 35 cm.
Growing varieties of leaf lettuce (rozetowej), not forming heads, you can get a yield of fresh green leaves faster. In Poland, the 'Kędzierzawa Yellow' and 'American Brown' varieties are grown. These varieties are planted in a row every 15-20 cm. The lettuce is cut several times or the leaves are constantly plucked. The first variety is suitable for early spring cultivation, the second can be cultivated even in summer.