Three years ago, I started growing a few different varieties of heirloom lettuce. To me, lettuce - more than any other vegetable - represents the highs and the lows of urban gardening. Is anything more satisfying than seeing the bright neon green of Amish Deer Tongue Lettuce peeking up through the dirt in spring? Is there anything more soul crushing than the discovery that your perfect head of Speckled Bibb has been nibbled to the ground by a flock of rough-and-tumble Brooklyn sparrows? This year I got wise and outsmarted the sparrows with the clever use of bird netting and row cover - leaving me with a bumper crop of tender spring lettuce. (A delicious bonus: laughing in the face of my sparrow nemeses.)
A Brief History of Lettuce
There are many varieties of lettuce, all descended from the original wild lettuce, probably native to temperate Asia and Europe. Scholars speculate that lettuce was originally grown not for its delicious, tender leaves, but for either the sap (or "latex") that is released from its stems when cut, or the oil found in the seeds. Lettuce latex is milky-white and has narcotic, sleep-inducing properties. Modern varietals have had this sedative trait mostly bred out, as the sap is extremely bitter. (Lettuce that bolts, or flowers, in the heat is usually bitter because the plant's latex is more pronounced.) One of the first historical records of a culinary use for lettuce is from the Egyptian empire, where lettuce is depicted on a tombstone dating from 4500 BC. The ancient Greeks wrote extensively about lettuce in their medicinal and culinary texts, and the Romans were big fans of the leafy green vegetable.
- Initially, Romans ate lettuce at the end of the meal to capitalize on its sleep-inducing affects; later, as the bitter quality in the sap was bred out of the varieties grown, lettuce was eaten at the beginning of the meal to stimulate the appetite.
- In the West, lettuce is frequently consumed raw, while in China, lettuce varieties bred for cooking are more common.
- Lettuce cores were candied for a 17th Century French dish called gorge d'ange ("Angel's throat").
- Heirloom lettuces include Red Leprechaun, Devil's Ears, Canary Tongue, Mascara, Tennis Ball, Tango, Flame, Grandpa Admire's and many other (interestingly named) varieties.
Aside from its heat-intolerance, lettuce is easy-to-cultivate lettuce and can be grown just about anywhere, but China, the United States (especially California) and India lead the world in lettuce production. The bulk of lettuce grown in the US falls into four categories: Loose-leaved (many heirloom varieties fall into this category); Butterhead (e.g., Bibb or Boston); Crisphead (e.g., Iceberg) and Romaine (or "Cos"). Globally, other varieties are grown mainly for their stem or for their oil-producing seeds.
Environmental Impact of Lettuce
Lettuce ranks a high number 11 (out of 53 ) on the Environmental Working Group's (EWG) Shoppers' Guide to Pesticides in Produce (see our vegetable rule of thumb*). The EWG recommends buying organic due to the high pesticide load in conventionally grown lettuce. In terms of global water footprint, lettuce ranks fairly low; however, conventional lettuce production relies upon monocropping(especially in California, where 90% of the leaf lettuce consumed in the US is grown) and irrigation from increasingly limited (and subsidized) sources.
In addition, conventionally grown lettuce has been implicated in several recent outbreaks of Salmonella, E.coli and Listeria, the most recent of which was a bagged lettuce recall (due to Salmonella contamination) in March of this year. The bulk of recent outbreaks have come from the increasingly popular "bagged lettuce" - lettuce that has been cut and "pre-washed," usually in chlorinated water. The centralization of food processing in conventional (and so-called "Big Organic") agriculture means that thousands and thousands of leaves of lettuce are processed in a single facility, so if one leaf is contaminated (from soil, animal waste or other contaminants), the entire batch of processed lettuce may become contaminated (similar to problems with the production of ground meat).
Because the overall environmental and health-related impact of conventional lettuce production is high, buying lettuce from local, sustainable sources may be your best bet to avoid pesticides and potential illness.
In most of the country, spring brings the most tender and sweetest lettuces. Lettuce is a cool weather plant - most varieties can't tolerate extreme heat and tend to become bitter as the season wears on. (By summer, in all but the coolest climates you'll be hard-pressed to find young lettuces at the market.) However, summer varieties of lettuce are now grown, and a second crop of most varietals can be planted in the early fall (prior to the first frost), extending the lettuce season dramatically.
The nutritional value of lettuce varies by variety - iceberg lettuce is far lower in nutrients than its cousins with dark green, red or speckled leaves. Lettuce is high in fiber and low in calories, and contains good amounts of vitamin A, vitamin C, calcium, potassium, folate and iron.
What to Look for When Choosing Lettuce
Lettuce comes in many different varieties and colors. Loose-leaf lettuce is just that - leaves are cut loose (i.e., not bunched into a head), while Romaine and Crisphead lettuce varieties are (usually) bought as a head. You can find purple, red, bright green, dark green (and every other color of green), speckled and variegated varieties of lettuce at the market.
Look for leaves that are intact and not wilted, with no browning, discoloration or sliminess. (For head lettuces, the outermost leaves should be discarded anyway, so a slight amount of browning or discoloration is OK).
What To Do with Lettuce
How to Store Fresh Lettuce
Romaine and iceberg can be stored in the refrigerator for up to a week (or even more), but loose-leaf and Butterhead varieties deteriorate quickly and should be consumed within a couple of days of purchase. Very young, tender lettuces may not last more than a day in the refrigerator, and so should be eaten immediately. To increase storage time in the refrigerator, I put lettuce in large zip top bags (don't pack too tightly) and top with a cool, damp kitchen or paper towel. Keep lettuce away from fruit that emits ethylene gas (such as apples and bananas) because they will hasten its deterioration. And always, always wash your lettuce (even if, and maybe especially if, you buy "pre-washed" bagged greens) in cold water.
How to Cook (or Not Cook!) Lettuce
Although recipes for cooked lettuce exist, including lettuce soup, creamed lettuce, braised lettuce (check out this recipe for braised peas and lettuce) and grilled Romaine, lettuce is most often consumed raw, in salads and as wrappers for various hot and cold savory fillings. In general, lettuce has a pleasingly sweet-bitter taste, and many varieties have a nice crunch. Crisphead types, like iceberg and Romaine, are mild in flavor and very crunchy - these varieties hold up to being sandwich toppers or being tossed with heavy or creamy dressings. Loose-leaved and Butterhead varieties tend to be softer and sweeter and may wilt under the weight of heavy dressings. I find that very fresh, young lettuces need only a tiny glug of extra virgin olive oil, a pinch of salt and a squeeze of lemon.
Stretching Your Fresh Food Dollar Though Preservation
Sadly, lettuce is very difficult to preserve - its delicate leaves don't take well to freezing, pickling or canning. Lettuce should be eaten as close to purchase (or picking!) as possible.
Recipe: Simple Dijon Vinaigrette
This recipe works for all lettuce varieties, but is especially suited for Butterhead types such as Bibb or Boston. It will keep for up to a week, stored in a glass jar in the refrigerator. To be extra fancy, stir in a tablespoon of chopped tarragon.
Makes about 1⁄2 cup
2 Tbs. good-quality white-wine vinegar
Generous pinch kosher salt
One garlic clove, smashed
1 Tbs. Dijon mustard
6 Tbs. extra-virgin olive oil
Freshly ground pepper and kosher salt, to taste
1. In a small bowl, add the vinegar, kosher salt and garlic clove. Steep the clove in the vinegar/salt solution for at least 15 minutes, and up to and hour. Remove clove and discard.
2. Wisk in the mustard.
3. In a slow stream, whisk in the olive oil until it is fully incorporated (emulsified). Stir in freshly ground pepper, and season with salt, to taste.
(*Vegetable rule of thumb: We think that first and foremost, in terms of nutrition, people should eat lots of fruits and vegetables whether they are organic or not. The EWG's guide is a handy list, but we will point out here that the impacts of pesticides are not limited to your ingestion of them - agricultural chemicals also affect farmworkers and local waterways, both good reasons to buy organic, even those vegetables that carry a light pesticide load. Also, it has been demonstrated that produce grown by small-scale farmers, even those who are not certified organic, tends to have a lighter pesticide load than its industrially-produced counterpart, owing to industry's tendency toward large monocrops.)
This post was originally published June 2012.