When I moved to central Virginia 25 years ago, my gardening neighbors believed that lettuce couldn’t be grown in winter. I set out to prove that we could indeed produce a continuous supply of salad greens year-round. I garden at Twin Oaks Community, where we plant 120 lettuces each week — enough to feed 100 people. By late September, we’ve made our 46th sowing of the year. Although we cultivate much more than you’ll likely need to grow yourself, you can still apply our planting strategy to enjoy fresh, homegrown lettuce throughout winter on a smaller scale.
A simple way to extend your harvest is to sow several different lettuce cultivars on the same day, each day you plant. You should plant cultivars with various numbers of days to maturity, including at least one fast one and one slow one. Bibb and romaine lettuces will mature quickly. Loose-leaf lettuces, such as the 50-day salad-bowl cultivars, are very useful because you can harvest individual leaves while you’re waiting for the heads to reach full size.
Choose cultivars that are suited to the season — those with “winter” in their names are good bets. I also like to plant cultivars that differ in color and shape. There’s no reason to get bored with lettuce!
In fall, to ensure winter harvests, we transplant lettuce seedlings from the garden into cold frames, an unheated greenhouse, and a hoop house. (At its simplest, a hoop house is a hoop structure covered with clear plastic; see Season Extension for plans.) We’ll have enough lettuce to feed us through winter if we protect these plants from the cold. Lettuce planted inside a cold frame may not make it all the way through the winter. For an extra layer of frost protection, we toss old quilts on our cold frame lids on nights the temperature will fall below 15 degrees Fahrenheit. Inside the hoop house, we’ve had lettuce survive at 10.4 degrees — and, under good row cover, down to minus 2.2 degrees! Our hoop house averages about 6 degrees warmer than outdoor temperatures.
Half-grown lettuces are more cold-hardy than full-sized plants. Small and medium-sized plants of the following cultivars can survive down to 15 degrees: ‘Marvel of Four Seasons,’ ‘Rouge d’Hiver,’ and ‘Winter Density.’ I’ve also seen small, unprotected plants of the following cultivars survive down to 5 degrees: ‘Winter Marvel,’ ‘Tango,’ ‘North Pole,’ and ‘Green Forest.’ Other particularly cold-hardy lettuces include ‘Brune d’Hiver,’ ‘Cocarde,’ ‘Lollo Rossa,’ ‘Outredgeous,’ ‘Rossimo,’ and ‘Vulcan.’
Before we built our double-layer hoop house, we grew lettuce outdoors in winter under two layers of row cover. Most lettuces can survive an occasional dip to 10 degrees with good cover. Depending on the thickness of the row cover, the interior can be 4 to 6 degrees warmer than the outside temperature. Our lettuce survived, but didn’t produce enough for frequent harvests. August 29 is our last sowing date for planting outdoors under row covers. You should experiment with frost protection and cold-hardy cultivars to discover what will work in your garden. If you’re in a cold climate, consider adding inner tunnels within your hoop house and adjusting the planting dates.
Sowing in September
September is a great month to plant lettuce for a winter crop. We sow lettuce every two days during the first three weeks of the month. Lettuce seed germinates best at about 70 degrees — although it will also sprout at temperatures in the 40s — and prefers cool nights. In fall, you’ll need to plant more frequently because a one-day difference in sowing can result in a week’s difference in harvesting. The rate of growth will slow down when the weather cools, and the harvest dates of those September sowings will spread out.
Here’s our September planting schedule in our Zone 7a garden, with an average first frost date of Oct. 14.
Sept. 1, 3, 5, 7, and 9. Every other day during the first week of September, we sow lettuce that will later be transplanted into our cold frames between Sept. 25 and Oct. 8. We’ll harvest leaves from these plants from mid-November to late February, when we need the space inside the cold frames to harden off transplants. If your cold frame isn’t well-insulated and frigid weather threatens, you should be prepared to harvest all the plants at once.
We plant these cold-hardy cultivars for our cold frames: ‘Green Forest,’ ‘Hyper Red Rumple Waved,’ ‘Merlot,’ ‘Midnight Ruffles,’ ‘New Red Fire,’ ‘Oscarde,’ ‘Pablo,’ ‘Panisse,’ ‘Red Salad Bowl,’ ‘Salad Bowl,’ ‘Winter Marvel,’ and ‘Winter Wonderland.’
Sept. 11, 13, 15, 17, 19, and 21. During the second week of September, we sow lettuce every other day that will eventually get transplanted into our unheated greenhouse. During the winter and until February, we harvest those lettuces by the leaf rather than cutting entire heads. The green and red salad-bowl types do well in the hoop house and the unheated greenhouse (where temperatures rarely reach freezing), although they’re not cold-hardy enough for growing outdoors in Zone 7a. For the greenhouse, we plant ‘Green Forest,’ ‘Hyper Red Rumple Waved,’ ‘Kalura,’ ‘Merlot,’ ‘Midnight Ruffles,’ ‘New Red Fire,’ ‘Oscarde,’ ‘Panisse,’ ‘Red Salad Bowl,’ ‘Red Tinged Winter,’ ‘Revolution,’ ‘Salad Bowl,’ ‘Tango,’ and ‘Winter Wonderland.’
Sept. 15 and 24. We sow hardy leaf cultivars on these dates to transplant into our hoop house on Oct. 15 and 25. We’ll harvest these lettuces by the leaf from mid-November through March. In our hoop house, it takes two months to grow lettuce big enough for leaf harvest — and we make sure not to over-harvest in winter.
For these planting dates, we like ‘Green Forest,’ ‘Hyper Red Rumple Waved,’ ‘Merlot,’ ‘Oscarde,’ ‘Outredgeous,’ ‘Panisse,’ ‘Red Salad Bowl,’ ‘Red Tinged Winter,’ ‘Revolution,’ ‘Salad Bowl,’ ‘Tango,’ and ‘Winter Wonderland,’ and the Osborne multi-leaf lettuce types, such as ‘Multired 54 MT.’
Sept. 24 and 27. These are insurance sowings. I like having backup in case of poor germination, rabbits, groundhogs and so on.
Oct. 23 and Nov. 9. We sow “filler” leaf lettuces in our hoop house on these dates to use until Jan. 25, filling in gaps left by harvested plants. We sow fillers without worrying that we won’t need them, because we can always harvest them as baby lettuce mix.
Baby Lettuce Mix
During the last week of October, we sow baby lettuce mix directly into the soil inside our hoop house. We follow up with subsequent sowings on Dec. 31, Feb. 1, and Feb. 15. We sow 10 rows, 41⁄2 inches apart, in a 4-foot bed. That results in a lot of lettuce!
Baby lettuce mix is a cut-and-come-again crop, meaning the plants will regrow and can be harvested more than once. We weed and thin baby lettuces to 1 inch as soon as we can see the seedlings well enough to do so. When the plants are 3 to 4 inches tall, we cut them about an inch above the soil, using large scissors or shears. I gather a small handful with my left hand and cut with my right. Immediately after harvesting, I weed the just-cut area so the next cut won’t include weeds. We’ll get our first cut somewhere between Dec. 5 and Dec. 22, and we may even get as many as eight total cuttings during winter. Baby lettuce will turn bitter here from late February to mid-March and will need to be pulled. We’ll have some later sowings to take over before that happens.
The baby lettuce cultivars we like are Fedco’s 2981LO Lettuce Mix (contains at least six different lettuces) and Johnny’s Allstar Gourmet Lettuce Mix (including ‘Green Oakleaf,’ ‘Red Romaine,’ ‘Lollo Rossa,’ and more). One ounce of seed will sow about 600 feet.
One year, cutworms ate our outdoor lettuce in August and September. To play catch-up until the hoop house lettuces were ready, we sowed some baby lettuce mix outdoors on Sept. 16. Our unprotected lettuce mix was ready to cut on the 35th day after sowing. (Admittedly, we had a warm spell that helped it grow faster.) We didn’t have enough ready-made lettuce mix seed on hand because we hadn’t planned to sow it outdoors, so I made our own mix of seasonally appropriate leftover fall cultivars — and you can try the same in your garden.
The flavor of lettuce produced during warm, late summer days and cool nights is often unsurpassed — a delicious combination of succulent crunch and sweetness.
Pam Dawling grows lettuce year-round at Twin Oaks Community in central Virginia. She writes for Growing for Market magazine. Her book, Sustainable Market Farming, is available in the Mother Earth News Store.