Butterhead lettuce

Lettuce is an annual and dies after harvest or seed formation. Sow anew every year, started indoors from February/March, directly outdoors from April. If you want winter lettuce, choose hardy varieties such as ‘Winterbutterkopf’ or ‘Winterkönig’, sow them from mid-August to mid-September and cover the rosettes with horticultural fleece in severe frost.

You propagate lettuce exclusively by sowing, because the plant is an annual and forms neither runners nor divisible rootstocks. From late January/February you can start it indoors: put two seeds per cell in seed compost. Important: lettuce needs light to germinate. Cover the seeds only very thinly (at most 0.5 to 1 cm) with fine soil or press them in lightly, otherwise they germinate poorly. Place them in a bright spot at 10 to 15 °C and keep them moist. The seedlings come up after 7 to 10 days; thin to one strong plant per cell. From mid-March you plant the young plants outdoors (spacing 25 to 30 cm). Direct sowing outdoors is possible from April, as soon as the soil no longer freezes. For a continuous harvest, sow again every 2 to 3 weeks. Beware of heat: above about 20 °C, lettuce refuses to germinate (thermodormancy). For summer sowings, it is best to sow in the evening, place the tray somewhere cooler or chill the seed briefly beforehand. For your own seed, let individual plants of an open-pollinated variety (not F1 hybrids, which do not come true) bolt into flower. The seed heads ripen unevenly over several weeks; the first are ripe about 2 to 3 weeks after flowering, recognisable by the small white fluffy tufts (pappus). Harvest them in portions when they come away easily. Stored dry and dark, lettuce seeds stay viable for around 3 to 4 years.