It’s easy to poke fun at iceberg lettuce. About the best thing you can say for it is that it’s crisp and it doesn’t taste bad. Of course, it doesn’t taste particularly good either. In almost every way you look at it, iceberg lettuce is nothing more than crunchy water.
But when viewed from a certain angle—that of industrial engineering—iceberg lettuce becomes a lot more interesting. An iceberg lettuce field is about as close to a widget factory as farming can get. Iceberg lettuce is grown on a massive scale at an amazingly constant rate (seasons mean little or nothing to the iceberg industry). It is firm enough that it can be picked and packed with a minimum of trouble, and it is hardy enough that it can be stored as long as three weeks without noticeable ill effect. In short, it is just about the perfect product for industrial agriculture. But like so many other industries, the growing of iceberg lettuce is changing rapidly.
Lettuces were almost certainly among the first plants humans ate. After all, in their most ancient form, they were nothing but wild leaves. They also were among the first crops domesticated. Egyptian art from about 2500 B.C. depicts fairly accurately a variety of lettuce that is quite similar to one that is still being grown in Egypt today. This is not a lettuce most of us would recognize. It resembles romaine, but its leaves grow out of thick stems that look like celery stalks.
For the second half of the twentieth century, however, if you said “lettuce,” it was pretty much assumed you meant one thing: iceberg. Introduced in the 1940s, iceberg lettuce is a refinement of an old lettuce family generically called “crisphead.” In Europe these and similar varieties are called Batavias. In the 1920s, in response to a lettuce blight that was threatening the industry, a USDA plant breeder named I. C. Jagger began a series of refinements that resulted in the first true iceberg lettuce, called Great Lakes, which was released in 1941. (A named variety called Iceberg predates this lettuce, but that is coincidental; it is softer and smaller than true icebergs.) Descendants of the Great Lakes family, called the Salinas family, still dominate the iceberg industry. There are dozens of strains, each specifically developed for a certain climate, growing area or production window.
Iceberg is a very good lettuce, if crunch is all you care about. For more than forty years, its ease of growing and resistance to disease and rough handling made it by far the dominant lettuce in the country. A leaf of iceberg inevitably went on nearly every hamburger sold; shredded, it topped almost every taco.
Iceberg is grown up and down the state of California and even into the Arizona desert, depending on the time of year. (California alone produces almost three quarters of the iceberg grown in the United States, and the two states combined grow about 98 percent.) Iceberg is a cool-weather crop, growing best when daytime temperatures are in the low 70s, cooling to the mid-40s at night. If the daytime weather gets into the 80s or nighttime lows are in the 50s, the lettuce can bolt, sending up shoots with flowers and seeds and turning bitter. To catch those optimal temperatures through the different seasons, the iceberg harvest is almost constantly on the move. During the winter, growers work ground in the desert areas along the Colorado River in California’s Imperial Valley and around Yuma, Arizona. As the weather warms, they move to the Central Valley for a couple of months. Iceberg is also grown along California’s southern coast, from northern San Diego to Santa Barbara.
But just about the perfect location for growing lettuce is the Salinas Valley, about one third of the way from San Francisco to Los Angeles. Here the pressure cooker heat of the Central Valley is moderated by a break in the Coast Ranges leading to Monterey and the Pacific Ocean. The Salinas Valley calls itself the Salad Bowl of the World, and that description is only slightly exaggerated. The first major planting of lettuce went into the Salinas Valley in the early 1920s, and lettuce acreage quickly skyrocketed. In 1922 roughly 300 acres were planted with iceberg; by the end of the decade, that number had risen to 43,000. Today there are about 65,000 acres of iceberg in the valley—a little less than half the state’s total. Indeed, driving through the valley during most of the year, you spend what seems like hours passing through lettuce field after lettuce field with little else in between. That’s because not only is lettuce grown on a massive scale in the Salinas Valley it is also grown for a long time.
Whereas other areas can harvest for only two or three months before the weather turns too hot or too cold, in the Salinas Valley lettuce can be cut from April through November. Between planting and harvesting, lettuce is nearly a year-round crop there. In fact, there is a county-enforced break in lettuce production during the month of December to break the life cycle of certain viruses. Farmers there traditionally spend the long Thanksgiving weekend breaking down the equipment necessary for harvesting and packing lettuce, then trucking that equipment south to Yuma or the Imperial Valley.
Although lettuce is grown on an industrial scale, it is still sold like a commodity. A case of iceberg fluctuates in value on a daily basis. The weird thing is that for much of the year, the farmer usually gets paid less for the lettuce than it costs him to grow, harvest and ship it (on average, approximately $10 per twenty-four-head carton).
If this sounds like a questionable business strategy, welcome to the world of iceberg economics. Lettuce farmers are agriculture’s version of day traders or riverboat gamblers. They break even or take losses many weeks in hopes that somewhere down the line, they’ll catch weeks when everyone else runs short of lettuce and the price takes off. This is one reason the same grower will usually maintain fields in several different parts of the state. Because so much iceberg lettuce goes to fast-food restaurants, the demand is fairly constant. All it takes for a price bump is a slight hiccup in supply. This happens regularly but unpredictably. A spell of unseasonable weather can double prices overnight.
And every once in a while, the price does more than bump up. In March 1995 more than 10,000 acres of farmland around Salinas flooded, wiping out as much as half of the lettuce supply. The price of a case of iceberg, normally around $10 to $12 in March, doubled to $24. Then it went to $36. Then to $60. There were reports of lettuce prices of up to $100 a case. How expensive was iceberg lettuce? Some restaurants started serving fancy arugula salads at staff meals because even that was cheaper. Of course, it doesn’t take an event of that magnitude to cause prices to rise. A couple of months later, after the harvest had recovered and prices had returned to normal, a case of iceberg went back up to more than $25 when a brief hot spell caused light picking.
Still, the glory days of iceberg farming are probably in the past. In the mid-1970s iceberg accounted for more than 95 percent of the lettuce production in the United States. But then tastes changed, and so did iceberg’s fortunes. This happened in two different directions. At the high end came the advent of the Chez Panisse salad, a mix of various kinds of tender leafy greens that were almost unknown at that time, all tossed together to produce an interesting combination of flavors and textures.
At roughly the same time, what could be called the “Caesaring” of the American salad began. Restaurants as varied as Burger King and the French Laundry began selling some variation of the Caesar salad, which is traditionally made with romaine. By 2000 iceberg’s share of the lettuce market had plummeted to less than 60 percent, while romaine’s had climbed from nearly nothing to roughly 20 percent. In 1993 about 16,000 acres of romaine were grown in California; ten years later there were more than 60,000.
But even those statistics somewhat underestimate iceberg’s fall from grace. Because during the 1990s, there began another revolution in the lettuce fields—bagged salads. Rather than buying whole heads of lettuce and mixing them at home, new technology allowed cooks to buy greens that had already been cut and mixed at the packing shed. At first this product was intended mainly for institutional use—big bags of chopped salad would save lots of labor in hotel and hospital kitchens. But today between 35 and 40 percent of the lettuce grown in the United States winds up in one of those salad bags.
Although rarely trumpeted on the label, iceberg, shredded into pieces, is often included in bagged mixes. Americans, it turns out, still want to have some crunch, even in supposedly sophisticated salads. But if you take away the iceberg that goes into the shredder you’ll find that the production of whole-head iceberg has fallen to less than 40 percent of the lettuce crop today. Ironically, while iceberg lettuce is taking a dive here, it is being increasingly planted in Europe, where it is perceived as a hot new thing.
Leading the charge against iceberg is romaine, which is called cos in Europe. Romaine is an entirely respectable lettuce, combining what is good about iceberg (the crunch) with a sweet, more emphatically green flavor. The other main families of lettuce grown in the United States are leaf, which forms very loose, rosette-shaped heads (think green and red oak leaf), and butterhead, which has loose, round heads with soft leaves (think Bibb). These generally have a fairly mild flavor and tender texture.
Of course, in today’s crazy mesclun world, many of the things we eat as lettuces aren’t really that at all. Some are endives, which are closely related to lettuces but tend to be coarser in texture and more bitter in flavor. There are about as many endives as there are lettuces. Belgian endive (Cichorium intybus), sometimes called witloof chicory, is the one that is usually forced into those long, white, tapered heads. Forcing really does raise farming almost to the level of industry—or at least high craft. Belgian endive plants are started in the field. After they leaf out, they are dug up, the green tops are trimmed, and the bases are replanted in a warm, dark room. This prevents the plant from developing chlorophyll, which would turn it green and change the flavor.
Another leafy endive (Cichorium endivia var. crispa) goes by the name of salad chicory. It has curly, deeply notched leaves that are dark green on the outside, brightening to pale yellow or almost white at the center. (High-flown frisée is a slightly different variety of the same family.) This leafy endive is sometimes mistakenly called escarole. True escarole (which is another variety of C. endivia — latifolium) has broad leaves arranged in a loose head looking much like a fleshy type of leaf lettuce.
Then there is the multitude of radicchios, a noisy Italian family of C. intybus. The round iceberg lettuce-looking variety, Chioggia (officially, rosa di Chioggia) is the most familiar, but there are several others. Castelfranco forms looser heads, more like Bibb lettuce than iceberg, and is a gorgeous pale green mottled with red flecks. It looks something like an old-fashioned cabbage rose of a peculiar hue.
Treviso is a type of radicchio with a long, tapered head that is almost always used for cooking. (All three names—Chioggia, Castelfranco and Treviso—come from towns in the Veneto.) One traditional form of Treviso, called tardivo, needs to be hand-forced, the way Belgian endive is: plants are grown in the field, then cut and stored in the dark, where they continue to grow without developing chlorophyll. This coincidence of techniques is not accidental. The method for forcing tardivo was perfected by a Belgian endive grower, Francesco van den Borre, in the 1860s. The leaves of tardivo grow on long, white, spidery stems. It looks like some kind of exotic lily and is incomparably creamy and sweet when cooked. Because growing it takes so much work, it is rarely seen in the United States, and when you do find it, it is usually expensive.
In the 1950s plant breeders came up with another form of Treviso that doesn’t require transplanting. It is called precoce (precocious) because it has the added advantage of maturing earlier than tardivo. Neither quite as sweet nor as creamy as tardivo, precoce is still very good when cooked. It is also more commonly available in the United States; look for something that resembles a big, red Belgian endive.
Lots of the greens we eat in salads today are the immature leaves of young vegetables—beets, kale, spinach, various mustards and swiss chard. These are generally tender and vary in taste according to the vegetable from which they come. Anise-flavored shiso and mustardy tatsoi and mizuna are the leaves of Asian vegetables. Salad mixes frequently contain herbs, such as chervil, flat-leaf parsley and basil. Some of the greens are what in less enlightened times would have been called weeds. Is there a gardener alive who has not cursed dandelions and purslane? Although these plants may be invasive, their peppery, slightly bitter leaves are welcome additions to mixed salads. And although it’s hard to think of violet-scented mâche and spicy arugula as weeds, if you’ve ever planted them and let them go to seed, you know that they can make a dandelion look passive. At one point, such greens caused much hilarity among not-yet-fine diners who derided them as “lawn clippings.” Fast growing and easy to harvest, they are turning into a big business. Since 1995 the acreage of “spring mix” in Monterey County alone has gone from about 500 acres to more than 12,000. You could say the lettuce industry is moving from widgets to weeds.
WHERE THEY’RE GROWN: Lettuces are grown up and down the Central Valley of California, extending into the southeastern part of the state and the area around Yuma, Arizona. They are also grown on a less industrial scale around the country, as they are one of the most popular farmers’ market items.
HOW TO CHOOSE: It’s no great mystery when lettuce starts to wilt. With head lettuces, make sure they are heavy for their size. In heat spells, the heads get lighter.
HOW TO STORE: Keep lettuce tightly wrapped in the refrigerator. Don’t wash it until you’re ready to use it. Moisture will break down the leaves faster than anything except heat. Sometimes you’ll get lettuce from the market that is dripping with water from overactive misting in the produce section. If this happens, stick a dry paper towel in the bag with the lettuce to absorb any excess moisture. Refrigerate in the crisper.
HOW TO PREPARE: Tear lettuce into bite-size pieces. If you’re going to serve it right away, you can cut it with a knife, but many types of crisphead lettuce will brown at the cut edges if you do this too far in advance.
ONE SIMPLE DISH: Few dishes are simpler than a tossed green salad, but that doesn’t mean it is easy to get one right. Here’s the easiest basic technique for a perfect salad. Cut a garlic clove in half and rub it all over the inside of a metal, glass or ceramic salad bowl. (Wooden salad bowls are attractive, but they absorb oil, which almost immediately goes rancid, flavoring every salad you make thereafter.) Place the washed and thoroughly dried leaves in the bowl (one of those salad spinners is a great cheap tool). Drizzle over just enough oil to lightly moisten the leaves when you toss them. There should not be any oil left in the bottom of the bowl. Sprinkle with good vinegar—red wine, champagne and sherry all have their attributes—and toss again. The classic proportion of oil to vinegar is 3 to 1; taste and see what works best for you. Finally, sprinkle with salt, toss once more and serve.
You chop up some vegetables, put them in a plastic bag and stick them in the refrigerator. You come back the next day, and they’re wilted. You come back the day after that, and they’re halfway to rotten. And yet you go to the grocery store and see bags of precut greens and vegetables that look nearly perfect. What’s the deal?
The packaging of precut vegetables is one of the most amazing advances in technology in the produce world, the result of years of research and cooperation between scientists who study plants and plastics.
Remember that vegetables continue to respire, or “breathe,” after they’ve been harvested: they take in oxygen, and they give off carbon dioxide and ethylene. The rate at which they do this determines how quickly they spoil. Vegetables that have been cut up deteriorate even faster than whole vegetables.
At first researchers believed that if you could reduce the amount of oxygen reaching the vegetables, you could slow down the rate of respiration and extend their shelf life significantly. This worked in part—it delayed the kinds of spoiling associated with respiration. But another problem popped up. It turns out that when deprived of oxygen, vegetables begin to draw energy from their own tissues and so start on another kind of decay.
But what if you could create an atmosphere with only a little bit of oxygen and just the right amount of carbon dioxide and ethylene? By experimenting with different kinds of plastic films for the bags, scientists found a way to do this. Different types of plastic allow different flows of different gases. By combining several films, scientists were able to create plastic bags that allow a slow intake of oxygen and a rapid venting of carbon dioxide and ethylene. This extends the life of cut vegetables for days, if not weeks.
Of course, it was not quite that simple. Each vegetable has its own ideal mixture of gases and so requires its own special type of film. In addition, some vegetables require different mixes depending on the season and on harvest conditions. Last but not least, the plastic film not only has to work as a gas filter, but it also has to be able to hold the brightly colored printing that goes with commercial packaging.
The next time you pick up a bag of mixed lettuces at the grocery store, remember that that is no ordinary plastic bag.