About Iceberg Lettuce: Iceberg lettuce was bred from a French Batavian variety by W. Atlee Burpee & Co. in 1894. Wild lettuce, however, from which modern lettuce is derived, originated in Asia Minor. The ancient historian Herodotus records its presence on the tables of 6th century Persian kings, and throughout the following centuries it became a popular crop all over Europe. Columbus brought it with him to the New World, starting its spread over the North American continent. Without a doubt, lettuce now holds a place in nearly every garden on the globe.
Iceberg Lettuce Germination: Lettuce grows well in cool weather, so the first crop can be direct sown when the soil temperature reaches at least 35 degrees F, or as soon as the soil can be worked. If the soil temperature rises above 75 degrees F, the seeds become dormant. Direct sow the seed in rich soil and full sun, spreading them as thinly as possible in rows 1-2' apart; when the seedlings begin to grow, thin them to a distance of 8-12". Succession crops can be grown for fresh lettuce all season in areas with cool summers or warm winters; this is accomplished by planting a new crop every 2 weeks. For companion planting benefits, grow lettuce with onions, cucumbers, or carrots.
Growing Iceberg Lettuce Seeds: Since lettuce has very shallow roots, it needs adequate moisture in order to stay tender and sweet; keep the soil evenly moist. Applying mulch helps conserve moisture and control weeds.
Harvesting Iceberg Lettuce: Lettuce retains its crisp sweetness best when harvested in the morning. For microgreens, cut the entire plant above the surface of the soil as soon as it reaches a height of 2-3". Outer leaves of the plant can be gathered all season until the main stem of the plant starts to grow, at which time the leaves will grow bitter. To harvest the entire plant when mature, cut it just above the surface of the soil; lettuce tastes best when fresh, but keeps in the refrigerator for about a week.
Saving Iceberg Lettuce Seeds: As the days of summer begin to lengthen, the lettuce will bolt, or send up a stalk. To avoid selecting negative traits, gather seed from the plants that are slow to bolt. After the stalk flowers and produces pods, the pods will turn light brown and split open; in order to prevent seed loss, shake the head of the stalk into a bag every day. Alternatively, some seed savers remove the entire plant when most of the pods are ready for harvest, and hang it upside down to dry in a protected location. Shake the seeds from the pods or crush the pods in your hands. The seed will have white "feathers" on them that can be removed by rubbing the seed on a fine mesh screen. Store the seed in a cool, dry place for 2-3 years.
Detailed Iceberg Lettuce Info: Lactuca sativa. Annual. 85 days. 26,500 seeds per oz. 6-18" height. 8-12" spacing. Produces firm heads with bright green leaves and a white heart.