Cultivation

Protected ground — head lettuce

Lactuca sativa L. var. capitata L.

Agrotechnology of head lettuce in protected ground is characterized by strict control of lighting, a temperature gradient for head formation, and a specific humidity regime for the prevention of physiological disorders.

In the reference 7 varieties crop Head lettuce, where this is mentioned in the description.

Head lettuce varieties grown in protected ground require a day-night temperature difference of less than 8 °C to ensure tight leaf closure. Excessive day length triggers premature bolting, while insufficient light leads to the formation of loose heads. Recommended planting density ranges from 9 to 16 plants per 1 m² depending on the cultivar type, as over-thickening hinders proper head development.

During the head formation period, relative humidity is reduced from 75–80% to 65–70% to avoid rot of the inner leaves and the development of tipburn. Marginal leaf necrosis is a specific physiological disorder associated with intense transpiration. An important agrotechnical requirement is to minimize irrigation in the final weeks before harvest and to prevent water from reaching the root zone to avoid rot.

General information about the subject — on the page Protected cultivation.

Sources8

Varieties of Head lettuce mentioned in the description

Selection based on the description text, not on official evaluation: these data are absent from registers. For specific variety details, please refer to its profile.