OP. Known in this hemisphere as a Cos lettuce, on the other side of the world, typically referred to as Romaine lettuce. This is the classic choice for Caesar salads. A variety first sold as early as 1802 by Bernard M’Mahon of Philadelphia, under the name White Cos; in France it is known as Blonde Maraichère. This cos lettuce has tall, narrow, rounded leaves that come to point with heavy white ribs. Best harvested whole as it is a heading lettuce. The inside is tender and sweet.
Sow in early Spring, repeat monthly for continuous supply. Sow into trays, prick out at 2.5cm diagonal spacing when true leaves emerge. Transplant into fertile soil at 20cm. As some seeds require heat to germinate, lettuces DO NOT germinate if soil temperature is too high. In summer we have found lettuces do not germinate in glasshouse conditions, instead we germinate them in our shadehouse.