I really enjoy growing fall lettuce in my Vermont garden. Yes, it stretches the season and gives me a steady crop of crisp greens during those cold gray days, but there's more to it than that. For me, fall growing puts a whole new spin on gardening. It lets me think differently and view the plants and the weather in a new light. In spring, we start planting when the weather is cool and heading toward hot. But in the fall, it starts out warm and turns cold. So fall planting is a little bit like gardening in reverse.
Lettuce is the perfect crop for this backward gardening exercise because it grows well even when soil temperatures are in the 40° F to 50° F range. Lettuce also grows well with fewer daily sunlight hours than almost any other crop, and mature plants can withstand air temperatures as low as 25° F. But to succeed with a steady crop of late season lettuce, you must understand the critical differences between spring and fall plantings.
Lettuce germinates best in cool conditions-68° F to 72° F but a fall harvest often requires planting during the heat of late summer. So you may need to sow your first crops in flats in a cool location, then transplant them to the garden. Second, unlike those of spring, fall growing conditions go downhill, as the average daily temperature falls and the daylength shortens. That means you have to adjust your succession planting schedule. In spring, sequential plantings usually catch up with each other, but in fall, harvest time slows as the season goes on, and crops sown only a week apart in September will mature two to four weeks apart in November or December. Thus, you have to sow more frequently than in the spring. Reverse gardening may seem confusing at first, but we've made it easier by compressing the USDA Hardiness Zone map to three lettuce-planting regions: Region 1 represents zones 2 to 5; Region 2 includes zones 6 and 7; Region 3 encompasses zones 8 to 10.
Wherever you garden, the basics of fall lettuce care are the same. Because crops grow more slowly in fall, a side dressing of slow-acting compost-a half-inch layer mixed lightly into the soil surface before planting-is better than a quick-release bagged fertilizer. Sow directly in the garden when temperatures are below 80° F; until then, start seeds in flats and transplant into the garden after three to four weeks.
During cold snaps, you can protect the crop with hay, straw, or leaves, but in periods of cold, wet weather, these mulches provide perfect conditions for rot and mold growth. For long-term protection, a spunbonded poly cover such as Reemay is much better. If you're trying to take a crop of lettuce through the winter for spring harvest, add an organic mulch on top of the cover, or use a cold frame-anything from a wooden crate with a storm window laid over the top to a high-tech aluminum and acrylic, self-ventilating unit.
The most important ingredient in fall lettuce success, though, is a solid knowledge of your garden's climate and the nature of the changing seasons. To me, that familiarity is one of the most satisfying aspects of fall gardening. It helps to put me in touch with the seasonal changes, and helps me, as a gardener, to stay in tune with the season.
Sow twice a week from August through mid-September. In our mountainside garden, just a hundred miles south of the Quebec border, we have a very small planting window. The best time to start sowing fall lettuce here is the first week in August. But weather then is often too hot for lettuce to germinate well, so we start seeds in flats in our cool garage, and set the young plants out a few at a time every three to four days over a period of weeks starting around Labor Day.
Fortunately, gardeners in the rest of Region 1 have more time. In zone 4, you can sow lettuce until Labor Day; in zone 5, you can plant until mid-September.
When sown the first week of August, early varieties such as 'Black Seeded Simpson' (45 to 55 days) mature by mid-October, but early September sowings won't mature until Thanksgiving. 'Rouge d'Hiver', 'North Pole', and 'Arctic King' are also well suited to fall plantings in Region 1. For overwintering crops, though, only the hardiest kinds, like 'Winter Marvel' or 'Brune d'Hiver', are reliable. Many of the common American lettuces grow in the warmer parts of our Region 1; in general, the loose-leaf kinds recover more quickly from freezing than heading types.
Sow weekly from September through mid-October. The principles of fall growing are similar in this region, but the schedule is more forgiving. For the maximum length of harvest, sow seed beginning around Labor Day, in flats if the weather is still hot, and then directly in the garden once soil temperatures hold below 80° F. Keep planting every few days, or at least weekly, until about the middle of October or the onset of regular frosts. The last plantings may be only a few inches across by the time the ground begins to freeze and thaw, so protect young plants with a row cover or cold frame.
The specialized winter lettuces mentioned above will work well in Region 2, but so will almost any lettuce, with some protection.
Sow twice a month from October through March. This region offers the best conditions to grow fall and winter lettuce. The cool but not frigid weather from October through March is nearly ideal, and the daylength varies less than at higher latitudes. For the longest possible harvest, sow in flats in a cool location, and time your sowings so that seedlings are ready to plant out as soon as the weather begins to cool down. Start new crops every week or two, and keep a floating row cover handy in case temperatures drop into the 20s° F for a spell.
Choosing special varieties isn't necessary in the South. Any lettuce will do, so plant according to your own preferences. We like crisp-leaf varieties such as 'Diamond Gem' (also called 'Sucrine') and 'Green Ice' for sandwiches; for salads we favor Bibbs, the heat-tolerant 'Esmeralda', the red 'Four Seasons' (often sold as 'Merveille des Quatre Saisons'), 'Valeria', and an 'Oakleaf' or 'Salad Bowl' type.
A former contributing editor at National Gardening, Shepherd Ogden is the founder and past president of The Cooks Garden seed company.