As the weather warms up and we start planning our spring gardens, Master Gardener Ann Bartlett reminisces about lettuce, its history, benefits and growing habits.
I hail from the lettuce capital of the nation, Salinas, California. There, daytime high temperatures in July and August are in the upper 60s with an afternoon wind blowing off the cold Pacific Ocean. Summertime lows are typically in the 40s but can dip into the upper 30s.
Lettuce thrives there. Dad was a produce broker with clients all over the United States and even Canada. Our refrigerator was filled with carefully labeled and dated lettuce, which Mom was to prepare within forty-eight hours of its expected delivery—Dad’s quality control program so he’d be on top of any potential problems.
Origins
Native to the eastern Mediterranean, lettuce has been cultivated since Old Testament times. Back then there was only romaine, but the Romans had nine varieties of it. They believed it to have a calming effect and ate it at the beginning of meals to aide digestion.
Types
Today we enjoy three types of lettuce, of which romaine is the most nutritious. It is a good source of iron and calcium as well as vitamins A, C and E. Loose-leaf, nonheading lettuces, with their rosette of fringed or curling leaves are great as cut-and-come-again selections. Harvest the leaves about a quarter inch above the base of the plant to promote regrowth. Head lettuces such as Boston and Bibb lettuce have thick, soft textured leaves. These will keep two to three weeks in the refrigerator if stored unwashed.
How-to
Now is the time to plant lettuce here. The optimal soil temperature for germination is 60 to 70 degrees, but it will sprout in soil temperatures as low as 40 degrees. Romaine and iceberg lettuce can be grown from transplants, but the others grow from direct seeding.
Avoid excess nitrogen and phosphorus to prevent tip burn. This crop will tolerate light shade but prefers full sun. Once temperatures reach 75 degrees, lettuce bolts—that is, becomes bitter and goes to seed.
Fun facts
I have read that Thomas Jefferson grew head lettuce in the summer at Monticello. He would have eaten it boiled and served with some sort of sauce to offset the bitterness. Crispy iceberg lettuce was introduced by Burpee in 1894. After World War II, technological advances in refrigeration coupled with the development of the interstate highway system made this cool-season crop available year-round throughout our nation.
About the Hamilton County Master Gardeners
Hamilton County Master Gardeners are here to provide you with the latest university research-based gardening information. Whether it’s plant or pest ID, sick plants or general gardening advice, we are here to help!
Send an email to mghchotline@gmail.com with any questions, visit us at mghc.org, or sign up for our monthly newsletter.
Like this story? Click here to subscribe to more like this delivered weekly to your inbox!