Cool Season Salad Greens: Growing a Salad Garden

I'm often asked how I'm able to grow vegetables in the late fall and winter when it's so cold out. The answer lies in the amount of sunlight each day. Once the number of hours of sunlight drops below 10 (which happens in early November where I live), most plants stop growing. So, I'm not really “growing” food after November, I'm just keeping the cold-tolerant crops alive in their protective structures until I'm ready to harvest them.

In early summer, leftover seed packets are sorted and last-minute orders to seed catalogs are placed in order to begin planning a fall and winter garden. The seed of slower-growing leafy crops like kale, collards, and cabbage can be started indoors under grow lights for a mid-summer transplanting to the garden. Quick-growing salad greens are direct seeded from mid-August through mid-September, but if daytime temperatures are still soaring in late summer, several flats of lettuce, endive, escarole, Swiss chard, pak choi, and mizuna can be started indoors under grow lights to ensure a good harvest.

Picking the Right Site

You can grow various types of leafy crops in different types of containers, such as window boxes, fabric bags, or even repurposed furniture. Most of these fast-growing greens, like leaf lettuce, arugula, mizuna, mustard, Tokyo Bekana, and baby spinach, have shallow roots and don't need a deep layer of soil to produce a crop.

The best place to plant salad greens is in a sunny or partially shaded garden. Some shading in the summer can help delay bolting and extend the harvest. If there is no shade, you can create your own by floating a length of shade cloth over the top of hoops in the garden. In spring and fall, use those same hoops with row covers to protect from cold temperatures and frost.

5 Tips to Growing a Salad Garden

• Feed the soil. Salad greens grow best in fertile, moisture-retentive soil, so dig in some compost or well-rotted manure before planting. This is also a good time to add a granular organic fertilizer if necessary.
• Seeds versus seedlings. With greens like arugula, leaf lettuce, and baby kale ready to harvest just 30 to 40 days from seeding, direct sowing is the way to go. Plus, direct seeding allows dense planting if you’re aiming for a crop of tender baby greens. For larger plants or mature heads of lettuce, direct sow, thinning as plants size up, or start seeds indoors under grow-lights. The seedlings should be transplanted into the garden after 3 to 4 weeks of indoor growth.
• Steady moisture. Because most types of salad crops are shallow-rooted and fast-growing, they require an even supply of moisture. If the soil is dry for an extended period of time, the plants may bolt or the leaves will become bitter. It’s difficult to mulch around densely planted baby greens, but if you’re growing salad crops that form a head, like romaine or butterhead lettuce, a mulch of straw or shredded leaves will help retain soil moisture.
• Succession plant. Succession planting is simply following one crop with another to ensure a non-stop harvest. For a long season of high-quality greens, sow fresh seeds every 2 to 3 weeks, or use your grow lights to produce seedlings to plug into empty areas of the garden. Even container gardeners should succession plant. The same rules apply; pot up a new container with lightweight potting soil and fresh seeds every few weeks to replace spent greens.
• Interplant. I like to interplant fast-growing salad greens like leaf lettuce and arugula between slower-growing vegetables like tomatoes, peppers, and eggplant in the spring garden. The greens are ready to harvest in 30-40 days at which point, the slower crops are ready for the space.

Growing a Salad Garden – Greens to Grow

Salad greens can come in many different types and flavors. Growing your own salad garden allows you to have many options to choose from when making a salad. Some of our favorites include lettuce, Tokyo Bekana, and spinach because they have milder flavors. Adding a few spicy mustard greens, mizuna, turnip greens, or arugula can really make a salad more exciting. For an even more convenient option, many seed companies sell pre-mixed packets of salad greens that are perfect for a gourmet salad.

Mild flavored greens

I fell in love with the Tokyo Bekana cabbage a few years ago after growing it in raised beds and window boxes. It forms one-foot wide rosettes of frilly, lime green leaves that look just like leaf lettuce. It also has a mild, lettuce-like flavor and makes a great base for a salad of homegrown greens.

Komatsuna is a vegetable that is related to turnips. The plants have large paddle-shaped leaves that are upright. Baby leaves can be used for mixed salads while the larger leaves can be added to stir-fries, sauteed with garlic and sesame oil, or used as a wrap for fresh spring rolls or sandwiches.

This quinoa relative is both beautiful and productive. The plants form tall clumps of silvery-green foliage highlighted by a splash of hot pink at the center of each shoot. Plant magenta spreen in late spring, shearing the plants back every few weeks to keep them compact and encourage fresh growth. Eat raw in salads or cook as you would spinach.

Spicy greens

I enjoy growing a variety of mustard greens in my spring, autumn, and winter gardens because they're tolerant to cold weather and offer a lot of variety in leaf texture and color. The young leaves have a mild spiciness, but the mature leaves are much spicier. Stir-frying is the best way to prepare them. Some good varieties to try are Giant Red, Ruby Streaks, and ‘Miz America', which has deep burgundy foliage.

Mizuna can be sown in cold frames six weeks before the last spring frost or in the garden three to four weeks before the last expected frost. It has a mild, cabbage-like flavor that pairs well with other greens in mixed salads, but the mature leaves are sturdy enough to be tossed into stir-fries and wraps.

Season Extending Techniques

• Row Covers. It may look like a flimsy piece of fabric, but a row cover can easily extend the autumn harvest by about a month. There are several grades of row covers — light, medium, and heavyweight — with each offering varying degrees of frost protection. The covers can be laid directly on top of salad crops in spring and early fall, but with the heavy frosts of late autumn and during winter, they will need to be “floated” over top on hoops or other supports to avoid damaging foliage. 
• Cold Frames. If I could only have one season extender, I would choose a cold frame, a bottomless box with a translucent top that allows light to enter. A cold frame is an easy way to enjoy a bumper crop of gourmet salad greens throughout autumn and winter. The most basic type of cold frame is made of straw bales arranged in a rectangle and covered with an old window pane, shower door, or a piece of clear polycarbonate material. Our 3 by 6-foot cold frames are built from 2-inch local hemlock and topped with Lexan, a twin-wall polycarbonate that is more insulating than a single glass panel, less breakable, and also offers high light transmission.
• Mini Hoop Tunnels. A mini hoop tunnel is an easy-to-build structure that can be erected quickly over garden beds to offer autumn protection to salad crops and herbs, shelter tall, leafy kales and collards over winter, or overwinter immature greens like spinach for an extra early spring harvest. In late summer, I also use a mini hoop tunnel, covered loosely with shade cloth to establish beds of salad greens for autumn and winter. The shade cloth cools the bed and boosts seed germination.

I make the hoops for the garden beds out of 10-foot lengths of ½-inch wide PVC electrical conduit, bending them into an upside-down U shape. I secure the hoops by pounding 1-foot long rebar stakes into the ground every 3 feet or so, with the ½-inch PVC slipping easily over the rebar. For spring and fall protection, I often use a row cover, but for winter, I add a layer of 6 mm greenhouse poly over the top of the fabric for added insulation. I secure the covers well with sandbags, rocks, logs, or clips.

Salad Superstars

• Mache. Also known as corn salad, mache is an extremely cold-tolerant salad green that forms tidy rosettes in our autumn garden and winter cold frames. We harvest the small plants whole by slicing them off at soil level with a sharp knife, tossing them with olive oil, fresh lemon juice, and a dash of salt for a simple, but sensational salad. The plants grow just 4 to 6 inches in diameter and should be direct seeded six to eight weeks before the first fall frost. Come spring, leftover plants quickly self-seed, so if you don’t want a carpet of mache babies, pull the plants before they set seed.
• Claytonia. Also called ‘Miner’s Lettuce’, Claytonia is native to North America and a workhorse in our winter cold frames. We direct sow the tiny seeds about six weeks before the first fall frost, but it’s not until the cold temperatures arrive in November that the plants really begin to grow. The tender leaves can be picked throughout winter, with the plants eventually producing delicate, edible flowers.
• Mizuna. Packing less heat than peppery mustard greens, mizuna is a welcome addition to the autumn and winter salad bowl. The mild, cabbage-like flavor pairs well with other greens for mixed salads, or toss the mature leaves into stir-fries or wraps. Direct seed mizuna in cold frames or the garden two months before the first fall frost. In our garden, the deep green, brushed with purple foliage of purple mizuna has made it a favorite.
• Pak Choi (Bok choy). Thriving in the spring and autumn garden, pak choi produces rounded, spoon-shaped leaves in green, red, or purple. I like to pick the plants young, when they’re just 3 or 4 inches tall, tossing them whole in stir-fries or adding the leaves to salads. Direct sow eight weeks before the first fall frost in cold frames or garden beds. Try ‘Ching Chang’ or ‘Extra Dwarf.’
• Spinach. Spinach is a great choice for a fall and winter vegetable garden. Not only does it prefer the cool, short days of autumn over the heat of summer, but it also appreciates the ample moisture that fall often brings. Direct seed in a sunny area of the garden in late summer when the night temperatures begin to drop and within weeks, you will be rewarded with a dense patch of deep green leaves that will continue to produce until the hard frosts arrive. If you cover your bed of spinach with a row cover or mini hoop tunnel, the harvest can easily be extended into winter. Try ‘Monstrueux De Viroflay’ or ‘Giant of Winter.’
• Arugula. It was a simple patch of arugula that introduced me to cold-tolerant crops and brought winter gardening into my life. Today, we grow arugula year round, even in summer, when I sow seed in the shade cast by my tall A-frame trellises. For a fall and winter crop, plant arugula seed four to six weeks before the first frost, sowing in both garden beds and cold frames. 
• Swiss Chard. Unlike arugula or pak choi, which can bolt quickly at the arrival of summer, Swiss chard is a non-stop food machine, lasting well into late autumn even without the protection of a season extender. Pair it with a cold frame or mini hoop tunnel, and you’ll enjoy the nutrient-rich leaves into mid-winter. Opt for varieties like ‘Rainbow,’ ‘Flamingo’ or ‘Orange Chiffon’ that have brightly colored leaf stalks.  
• Tatsoi. With tatsoi in my cold frames, I say to Old Man Winter, “Bring it on!” Tatsoi shrugs off the coldest weather, forming low-growing, deep-green rosettes in our cold frames. Pick the leaves individually for cold-season salads, or pull the young plants whole for a stir-fry. We also grow tatsoi as a fall crop in the open garden, sowing the seed about six weeks before the first fall frost.
• Lettuce. Like spinach, lettuce thrives in the cool temperatures and increased moisture of fall. Start sowing seed directly in the garden about eight weeks before your first fall frost. Because lettuce seeds won’t germinate well once temperatures are above 77 degrees Fahrenheit (25 degrees Celsius), you can also start your seeds indoors under grow lights and move them to the garden about six to eight weeks before the first frost. Top cold-season picks include ‘Winter Density,’ ‘Brune D’Hiver,’ ‘Outredgeous,’ ‘Red Salad Bowl,’ and ‘Rouge D’Hiver.’
• Kale. As temperatures drop in autumn, the leaves of kale become even sweeter! Transplant seedlings into the garden in early summer for a non-stop crop of kale or sow seeds thickly in garden beds in August for a bumper crop of baby leaves to toss in salads and stir-fries. Favorites include ‘Lacinato’ (also called Dinosaur kale or Black Tuscan kale), which has excellent-tasting and highly puckered blue-green leaves, or ‘Red Russian,’ cold-tolerant kale with gray-green leaves and vivid purple stems.