If you live in a place other than the cool Northwest, you probably can’t provide ideal growing conditions for lettuce for more than 60 days each year. The rest of the time, it’s either too hot or too cold to grow decent lettuce.
But gardeners who love a challenge can pick salad greens 10 months a year by adapting a few techniques to their own climate and growing conditions.
Why grow lettuce in winter
I love winter gardening because it’s easy and I can harvest a lot of lettuce. With spring, summer, and autumn come extreme temperatures, bad weather, and pests. With winter, the only work I have to do is harvesting.
It’s important to point out that I’m not really “growing” lettuce in winter. The growth of most plants slows down dramatically when the day length shrinks to less than ten hours of light each day. In my northern region, that happens in early November. Therefore, I aim to plant and grow my lettuce in early to mid-autumn, and the plants then spend the winter protected in a season-extending device like a cold frame.
Two ways for growing lettuce in winter
There are two methods for growing lettuce in winter. The first one is planting in late summer or early autumn and the lettuce is cut from December through March. The other method is an overwintering technique with lettuce planted in mid-autumn. These plants start to put on growth before the deep freeze of winter arrives. At that point, they grow very slowly until the day length extends beyond ten hours once again in late winter. With the increased light, the plants size up quickly for harvesting in March and April.
Lettuce seeds should be planted in moist soil so they can germinate. If the soil is too dry, the seeds will not be able to grow. Planting the seeds indoors is a good way to make sure they are not too hot or too dry.
When to plant lettuce for winter harvesting
I’m often asked about the best time to plant vegetables for winter harvesting. While it may seem tricky to figure out, it’s actually very easy, especially for lettuce. First, decide if you want full-sized heads or baby lettuce for winter harvesting (or both!). Next, find out your first average fall frost date. Once you have those two pieces of information, it’s easy to determine the right timing for direct seeding and transplanting lettuce.
Growing full-sized heads of lettuce for winter
Here is some information on when to plant lettuce so that it will be mature and ready to harvest in winter.
Full-sized lettuce heads, direct seeded:
- Planting in garden beds (to be covered with a mini hoop tunnel or portable cold frame in mid to late autumn) – Sow seeds 10 to 11 weeks before the first average fall frost date.
- Planting directly in a cold frame, greenhouse, or polytunnel – Sow seeds 6 to 7 weeks before the first average fall frost date.
Full-sized lettuce heads, transplanted:
If you can’t find lettuce seedlings at a local nursery, you’ll have to grow them yourself. It’s best to sow the seeds indoors 3-4 weeks before transplanting them into a garden.
- Planting in garden beds (to be covered with a mini hoop tunnel or portable cold frame in mid to late autumn) – 6 to 7 weeks before the first average fall frost date.
- Planting directly in a permanent cold frame, greenhouse, or polytunnel – 6 to 7 weeks before the first average fall frost date.
Growing baby lettuce greens for winter
Although I enjoy cutting a head of lettuce, it is also convenient to have a variety of baby lettuce greens. This allows me to create salads with different colors and textures. Baby leaf lettuce planted in the spring can be harvested in just four weeks. However, the shorter days and cooler temperatures in autumn slow down the growth of the plants, so baby leaf lettuce planted in autumn will need five to six weeks to be ready for harvest.
Baby lettuce greens usually take a short time to grow and are not often transplanted. They also have a lot of seeds that are close together. For baby greens, I try to plant one seed per square inch of bed space. I keep the soil moist until the seeds grow and the plants are doing well.
For baby lettuce greens, direct seeded:
- Planting in garden beds (to be covered with a mini hoop tunnel or portable cold frame in mid to late autumn) – Direct seed 5 to 6 weeks before the first expected fall frost.
- Planting directly in a permanent cold frame, greenhouse, or polytunnel – Direct seed 4 to 5 weeks before the first expected fall frost date.
Varieties
There are many different types of lettuce, so it can be easy to get caught up in appearances. However, if your goal is to grow lettuce in less-than-ideal conditions, you need to look more closely.
Arctic King, Winter Marvel, Rouge d’Hiver, Yankee Hardy, and Black-Seeded Simpson lettuces, Astro arugula, and many beautiful cutting mixes blended for spring growing conditions all thrive in cool soil and relatively low light conditions. You should buy at least eight or 10 different kinds of seeds to have a long season of salad greens.
If you want lettuce that can withstand warm weather, try Larissa, Craquerelle Du Midi, and Rosalita. You could also try the spinach Regiment or Tyee, or look for a cutting mix blended specifically for warm weather.
If you want to know what plants will do well in your area, ask your neighbors or local market gardeners for their recommendations.
Seed starting
To get a continuous supply of salad greens throughout the year, you need to either sow a small amount of seeds indoors or outdoors every week.
You can start seeds indoors when it’s too cold or too hot to plant them outside. Put the seeds in a potting mix that is blended for seed-starting. Cover the pot with plastic wrap until you see the seeds have sprouted. Once the seedlings have their first set of true leaves, you can transplant them to individual growing cells and grow them for another two weeks before transplanting them to the garden.
As the greens get harvested, I replant them with something else. I sow seeds in two ways in my garden. I either let them grow freely in an unoccupied space, or I sow them in a bed where I plan to transplant them later. The latter involves planting short blocks of different greens that I can later harvest and replant.
You will definitely get more lettuce if you sow seeds every week or two. Seeds are cheap and it is easy to improve your chances of a good harvest by sowing them more often, especially when the weather is unpredictable.
Soil and Moisture
It is best to grow leafy greens in rich, loamy soil that contains plenty of organic matter. Use a trowel or hand fork to dig some compost into the top couple inches of soil before you sow or plant out your seedlings. Seedlings benefit from being watered right after transplanting with a weak solution of seaweed/fish emulsion.
Lettuce and other salad greens require a large amount of water to grow rapidly and produce tender leaves. The soil should be kept moist at all times to prevent the plants from experiencing stress. If summers are hot and dry, it is recommended to invest in a soaker hose or dripper line.
How to protect lettuce in winter
If you don’t live in a warm climate, you’ll need to use season extenders to grow lettuce in the winter. Here are three of my favorite structures for winter harvesting.
A cold frame acts as a bottomless box that uses solar energy to create a microclimate for plants. It can be made from untreated lumber and an old window, lightweight and able to be moved around, or bought from polycarbonate.
There are two main components to a mini hoop tunnel: hoops and a cover. The hoops are typically made from a sturdy material like 1/2” PVC conduit or 1/2” metal conduit, and are covered with row cover or polyethylene sheeting. For lettuce, a layer of lightweight row cover is usually sufficient, but as the weather cools, a sheet of polyethylene should be added overtop the row cover. This double layer provides excellent protection for winter-hardy lettuce varieties. Snap clamps are typically used to securely hold the covers on the hoops. If you don’t want to DIY a mini hoop tunnel, there are also various tunnel kits you can buy online.
If you have a walk-in structure like a polytunnel or greenhouse, you can use it to produce lettuce all winter long. I have a 14 by 24-foot polytunnel and grow about 60 heads of lettuce each winter. Lettuce is less cold-hardy than greens like spinach, so I add a second cover inside my tunnel in late December. I float a lightweight row cover over 9 gauge wire hoops for an extra layer of protection.
The best lettuces to grow in winter
Romaine lettuces for winter
I’ve been growing the Winter Density variety of lettuce for years and love the tidy heads of thick, crunchy deep green leaves it produces. Winter Density is a cross between romaine and buttercrunch lettuce and has been very reliable in my winter cold frames and polytunnel.
This variety of romaine lettuce is called “Rouge d’Hiver” which in French means “winter red”. It is a variety that has been passed down in a family and is a favorite of the family. It is characterized by its bright green leaves with red edges.
These attributes make it ideal for use in mixed containers and as a border plant. Winter Wonderland is perfect for gardeners who live in cold climates. The plants are large and full of deep green leaves. They can grow up to 18 inches tall and 12 inches wide. This makes them ideal for mixed containers and as a border plant.
Butterhead lettuces for winter
North Pole is a type of butterhead lettuce that can withstand cold temperatures, making it ideal for harvesting in spring, autumn, and winter. It produces small heads of lettuce with bright green leaves that are crunchy and sweet.
This is a French heirloom with beautiful green heads brushed in reddish-bronze. It is excellent for cold weather and is both beautiful and delicious.
Winter Marvel is an excellent addition to any garden because it is hardy, has a great flavor, and forms tidy heads.
Arctic King is a great vegetable to grow in winter or to overwinter as an extra-early crop. Each head forms a dense rosette of light green leaves.
Harvest Your Greens
You can cut salad greens in many ways. Always cut cleanly with a knife or scissors. Most greens will grow back after being cut, as long as you leave about half an inch of the plant. You can pick individual leaves, cut off entire heads, or crop mixes and leaf lettuce with scissors. Try different techniques to see which ones you like best.
In the winter, when there is less light, plants grow slowly if at all. When lettuces and other salad greens enter their winter dormancy period at a young age (less than four to six weeks old), they usually revive and start growing again as soon as the light returns. Even in the coldest climates, spinach and arugula will usually overwinter (survive the winter) under two layers of Garden Fabric, and be ready to harvest in March.
Leave a Reply