Lettuce
(Lactuca sativa sp.)

Cultivars

Even in winter, but of course especially in summer, a good salad is a treat for body and soul. And, while specialty salads--from a fresh sliced tomato with a little chive, parsley, olive oil, and vinegar to a beet-and-walnut salad--are many and pleasing, lettuce remains the bedrock of the salad-lover's crops. But there are lettuces and there are lettuces . . . .

Lettuce Types

There are a myriad of lettuce types, differing one from another in ways large and small. The most useful high-level classification is this:

• Heading lettuces, commonly called "iceberg lettuce" (cultivar Crispino shown):
  
  Everyone recognizes these, familiar from supermarket shelves and cafeteria sandwiches. Curiously, the type is quite modern, having been developed only a half century or so ago. Compared to all other lettuces, they require more growing space, have longer growing times, are more likely to bolt, are more susceptible to pests and diseases, have less nutritive value, and--by general agreement--have notably less flavor; naturally, they are America's favorite kind (though not the rest of the world's).
  
  
• Romaine lettuces, also called Cos lettuces (cultivar Rouge d'Hiver shown):
  
  This is a type known since, at the very least, Roman times. It achieved fame in America with the popularity of the "Caesar Salad". It has a more distinct and distinctive taste than most other lettuces, a very faintly bitter quality typical of flavored salad greens.
  
  
• Batavian lettuces: (cultivar Magenta shown)
  
  This wonderful type is scandalously unknown in the U.S. It is perhaps the hardiest of all lettuce types, withstanding summer heat excellently and, by most reports, winter cold as well. Moreover, many think it the best-tasting type of lettuce (sounds a no-brainer, doesn't it?) On the whole, the type is perhaps best described as "semi-heading"--it doesn't form a true head, but is not looseleaf either. But individual varities are fairly variable, some heading more distinctly than others.
  
  
• Butterhead (or Buttercrunch or Bibb) lettuces (cultivar Adriana shown):
  
  These heat-hardy and gorgeous leafy rosettes are as good eating as they are delightful to look at. They are also sometimes called "Boston" or "limehead" lettuces. Smaller ones are often used entire as one-person salads (they go wonderfully with a few mushrooms and a simple vinegrette). They are the most popular type in Europe.
  
  
• Looseleaf lettuces (cultivar New Red Fire shown):
  
  A type which scarcely needs explanation.
  
  

Within each broad type there are numerous variants, but we like to think of each as being divided into two sub-classes: "green" and "red"--where "red" rarely means more than purple-tinged or bronze (as with the "red" Sierra Batavian pictured above).

Choosing Cultivars

With some moderate care in hte handling of our growing area--as described farther down this page--one should be able to grow lettuce all the year round. Lettuce is a cool-weather crop to begin with, and is pretty cold-hardy. While it certainly can't grow out in the snow, only modest aid should be needed to keep it going. More difficult is summer growing, as lettuces notoriously bolt (go to seed) very quickly in hot weather. The answer there is (we hope and believe) modest protection, such as partial shading, but first and foremost careful selection of cultivars known to be heat-resistant.

A great help here are the results from the Colorado State University's Lettuce Bolting Resistance Project. We don't have to rely on seedmen's claims or individual anecdotal accounts: we have careful, methodic trial results available.

Regrettably, not all the cultivars their results point at remain readily available to home gardeners, but fortunately there are either clear successors or broadly applicable results, so we are satisfied with the list we have arrived at. It's a great shame that the former outstanding lettuces home-garden seedsman, A Cook's Garden, was sold by the Ogdens and is no longer anything special for lettuce and other salad-makings seeds; but Johnny's, in Maine, has evolved into a pretty good replacement, and many of our selections are unique to that seedsman. (We don't normally discuss sources on these pages, reserving that for our Seed Sources page, but here one cannot escape the subject.)

Broadly speaking, the Batavians are the undisputed kings of heat resistance, far ahead of all other types. Runners up are the butterhead types. A ways back are the romaines, but it looks as if by taking them fairly early (something home gardeners can do but that commercial growers cannot afford to), they, too, can be useful in summer. Leafy types don't do well, though that seems to vary more by cultivar than is the case with the generically more resistant types, and with, again, care in picking them early, certain cultivars might work. The project did not include any heading lettuces, but another university source notes that heading lettuces are "generally intolerant of hot summer conditions"--besides, we already know that they are scarcely worth the home gardener's putting himself out for, so we can grow a few in the cooler seasons if we feel a need, but no use wasting growing space in the peak of summer.

While you can look over the Project's actual results, as linked above--and also remember that scientific as the study was, other people in other places might get different results--here is the list we came up with after running their cultivars against what's readily available at present.

• Batavian:
  • Nevada - green
  • Magenta (improved Sierra selection) - red
  
  
• Butter:
  • Adriana - green
  • Fireball - red
  
  
• Romaine:
  • Green Forest (a "Paris Island" type) - green
  • Rouge d'Hiver (classic heirloom) - red
  
  
• Looseleaf:
  • Tropicana - green
  • New Red Fire - red
  
  
• Heading: Crispino - green

That does not mean that we would try to grow the same amounts of each type at all times: in the summer, we would grow mainly Batavians and the green butterhead and romaine (the green varieties of those types seem, from the data, to hold a little better), with a scattering of all the rest save the crisphead; in the winter, we will grow a more balanced selection, with the quantities asorted chiefly by our personal tastes in types.

We will, of course, modify our approach over time, as we see what actually works for us; but we feel confident that at the least the Batavians (which also seem a pleasant sort on their culinary merits) should get us through all seasons. Anything else, at least in summer and winter, is a bonus.

The Growing Area

In spring and fall, lettuces can be grown outdoors with no special considerations. But if we are to succeed in the cold of winter and the heat of summer, we need to take some measures.

Winter

As we said above, lettuces are by nature cool-weather crops--they supposedly can withstand air temperatures down to perhaps as low as 20° F., so in a region where the average coldest overnight low is 17° F. (though we can easily get, in this or that particular year, down to zero or below), we don't necessarily need measures so drastic as an actual greenhouse. What we will try this coming winter is some sort of crude cold frame, made with either real glass from salvaged windows or storm doors or some sort of plastic; we will also place large chunks of dark-colored stone in the ground around the bad (and at the north edge) to catch and hold heat. We water by drip irrigation, so can fairly well enclose the growing area. We think that should work, but we'll just have to see.

Summer

To mitigate the warmth, the simplest thing is to provide some shade. We'll have to see what makes more sense--some shading fabric or some latticed slats. But we are relying here mainly on the strength of the cultivars selected.

Planting

Timing

As we said above, lettuces are by nature cool-weather crops, and can withstand air temperatures down to perhaps as low as 20° F., so heat is the chief problem, for lettuces notoriously bolt quickly in warm to hot weather.

We have mentioned ways to keep lettuce viable through the cold of winter. But if one also takes measures (such as providing partial shade) at the other end, the summer, then it is at least possible that out here one can grow lettuce year round; if so, "planting dates" become meaningless. (And if not, one can switch, toward mid-summer, to one or another of the hot-weather lettuce substitutes, such as leaf amaranth.) That makes any question of "planting dates" meaningless.

One just needs to remember two things: to keep starting new plants periodically, and to timely switch from "warm-weather" to "cold-weather" cultivars. Taking that last first, it's a judgement call, but around here the "mid-season" dates are about April 15th and October 15th; therefore, allowing for growing time, we'd switch from sowing "cool" to "warm" types around April 1st, and from sowing "warm" types to "cool" types around October 1st.

As to when to sow another plant: you simply plant as often as you typically need new heads of lettuce. If, for example, you feel--as we do--that you need a head of lettuce roughly every three days . . . you sow a new plant every three days.

The reason one frets about timing, though, is its role in determining how many spots to reserve in the garden for a more or less continuous supply of lettuce. Let's look at numbers.

Lettuce is best handled hereabouts as transplants, but once we set them out in the lettuce bed, we should reckon that they will take, on average, perhaps 6 weeks of outdoor growing. (It's very important to understand how variable that "on average" is--it depends on the particular cultivar; it depends, heavily, on the season and the exact weather--lettuces grow slowly in quite cool weather and quickly, often too quickly, in warm weather; it depends on whether you are taking the whole plant at once or cutting a few leaves; it depends on the individual specimen of the plant; it depends on your soil; and we suppose it depends in part--as does all gardening--on sheer luck.) But call it 6 weeks.

So a typical lettuce spends 6 weeks--42 days--outdoors in the lettuce bed. If one assumes another head wanted every 3 days, which rate we feel is about our case (remembering also that we will have other greens to help fill the salad bowl), we divide 42 days by 3 and find we need 14 lettuces growing in the bed at any one time (which is just the space we provided), plus 7 seedlings indoors, all in a chain of 3-days-apart in their growth (though it's never quite as simple as that).

Starting Seedlings

Around here, we always start lettuces indoors as seedlings for transplanting. Sow into 1" seed cells or the like; use 2 or 3 seeds for each seedling wanted, then cull the weakest before they get too crowded. Don't let the seeds or seedlings get too warm: try to keep them below 65° in one way or another, and at all costs below 75°. Be sure to carefully harden off the seedlings: for 2 to 3 days before transplanting, reduce their water and the ambient temperature--that is especially important in the stressful days of low winter and of high summer.

(And remember to switch warm/cool types at the right times of year.)

The Bed

Lettuces are "greedy feeders", so be sure that the soil is good and rich for them. Something like 1 to 1½ pounds a square foot of compost or well-composted steer manure every year or two is a good idea (that's a layer about ½ to 1 inch thick). Though we hope to get lettuces (and other salad greens) growing year round, it's wise to move the lettuce bed at least annually, to minimize soil-disease risks--our own plan is two identical beds, each used for a year while the other is either fallow or used for some non-greens (and non-cole and non-solanaceae) catch crop.

Transplanting Out

Wait 3 to 4 weeks after sowing before transplanting out; 4 weeks is probably best in the high-stress summer and winter periods, whereas 3 weeks will likely be OK in spring and autumn.

When starting a new bed, space the new lettuces at about a foot; in the winter, though, you might make that more like 10 or even 9 inches, as they will grow more slowly and likely a little smaller (it's not a matter of saving space, but of trying to keep the mature plants' leaves just touching, as the proverbial "living mulch".)

After the bed is fully planted, whenever you remove a head of lettuce from the bed, just replace it with the largest seedling you have growing indoors. Plants are not factory-made: they grow at different paces, both as seedlings and as plants, so don't assume that the order in which you sow seed is necessarily the exact order in which you will transplant out (or that your transplanting order is the exact order in which you will harvest).

Growing

Keep them watered well and, perhaps above all, regularly. Irregular watering may be worse than scanty watering. Pick lettuce when it looks ready. Grow enough that you can afford to pick when the individual plants are of a modest size, lest you run the risk of having them bolt on you. Many leafy kinds can be harvested a few leaves at a time, which they will then grow back--what's called "cut and come again" harvesting.

More

Relevant Links

Besides any links presented above on this page, the following ought to be especially helpful.

• Plants For a Future Database: Lettuce - the main page for "lettuce": there are other pages (linked below) for certain particular types
• Plants For a Future Database: Lettuce - heading lettuces
• Plants For a Future Database: Lettuce - cutting lettuces
• Plants For a Future Database: Lettuce - Romaine/Cos lettuces
• Winter Lettuce - interesting mainly for its many photographs of lettuce types
• Lettuce varieties for home growing - from New Zealand: while their selections of particular types are now a little dated, the discussion of the basic classes is excellent

Odds and Ends

Biology

All the lettuces are from the Asteraceae (formerly Compositae) family, the asters, which includes many edible greens and some edible roots.

History

There are today literally thousands of different cultivars of lettuce--all sprung from ancestral wild lettuces that grew (and still grow) in Northern Europe, Asia, North Africa, and even parts of North America. There is good evidence that some sorts of lettuces were being cultivated in Egypt as early as 4500 B.C. Certainly the Babylonians were cultivating it by 3,000 years ago, and the Chinese may have started growing it before them.

Herodotus tells us that lettuce was served on the tables of the Persian kings of the 6th century B.C. In the 5th and 4th centuries B.C., other great Greek writers described and praised its virtues. The Greeks called it tridax, the Persians kahn. The plant's modern "scientific" (Latin) name, Lactuca, is derived from the Latin root word lac, milk; our English word "lettuce" derives from the French laitue, also meaning milk. That, obviously, is because the plant has a heavy, milky juice. The juice, or sap, was long thought to have significant medical properties: Hippocrates mentions lettuce sap as a medicinal, supposed to induce sleepiness.

By the first century after Christ, Roman writers were describing a dozen distinctly different lettuce types, some of which were fairly common; it is known that lettuces much resembling present-day Romaine cultivars were then being grown. (It was popularly believed in the time of Augustus that he was cured of an illness by eating lettuce.)

As in the development of the cabbages, the primitive forms of lettuce were loose, leafy, and sometimes "stemmy" types; the looseheading and firm-heading forms occurred much later. Firm-heading forms had become well developed in Europe by the 16th century, but just when they were first developed is unknown. The oak-leaved and curled-leaf types, and various other colors now known, were all described in the 16th and 17th centuries in Europe.

Columbus evidently carried lettuce to the New World, for its culture was reported on Isabela Island (now called Crooked Island) in the Bahamas in 1494. It was common in Haiti in 1565. When it was introduced into South America is not known, but doubtless it was soon after the Europeans arrived; it was under cultivation in Brazil before 1650.

Lettuces are today used almost exclusively raw, but they can be cooked--indeed, lettuce was normally eaten cooked till the time of Louis XVI, when the Chevalier d'Albignac famously dressed raw lettuce with a vinaigrette.

Envoi

Think lettuce, for all its virtues, is boring? Check out The Lettuce Ladies (this being the 21st century, female readers can check out The Broccoli Boys).

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