When summer draws to a close, it's time to think about planting all those delicious greens that thrive as the weather begins to cool. Lettuce, spinach, arugula, corn salad, mustard, and a variety of Asian greens are all great choices for a fall crops in many parts of the country. As the harvest of corn, tomatoes, zucchini, and other heat lovers wanes, these fantastic fall greens step in to keep your garden's bounty coming.

Fall greens are a great choice for school gardens because their harvest season fits in well with the academic calendar. Depending on your climate and use of crop protectors like cold frames, in many parts of the country students can be harvesting and even planting in the outdoor garden for at least a couple of months after the start of the school year.

As an added bonus, greens are nutritional powerhouses, full of vitamins, minerals, and health-promoting antioxidants. In fact, nutritionists tell us that, calorie for calorie, dark leafy greens are just about the most concentrated source of nutrition of any crop you can grow. Participating in the growing, harvesting, and tasting of a variety of greens is a great way to introduce young gardeners to this important dietary group.

Planting Site for Fall Greens

Full sun is best, but greens are adaptable and grow well even in sites that receive only 3-4 hours of direct sun a day. In fact, when planting in summer for fall harvest, some shade in the hottest part of the day will benefit cool season greens, especially in warmer climates. Greens thrive in fertile, moist, but well-drained soil. Most greens are also good choices for container growing.

When and How to Plant Fall Greens

The length of your fall growing season will depend on where in the country you garden. Gardeners in mild winter areas may even be able to grow successive plantings of greens throughout the fall and winter. Many greens tolerate some frost and will keep growing -- sometimes even improving in quality -- until quite late into the fall. Arugula, lettuce, spinach, corn salad (mache), mustard, Swiss chard, and hardy Asian greens like mizuna and taht soi take light frost (temperatures between 28 and 32 degrees F). Hardy kale and collards will survive even frostier temperatures, down to the low 20s.

Of course, if you provide your plants with some frost protection in the form of a cloche, row cover, cold frame, low tunnel, or even just some old sheets tossed over plants on a cold night, you'll be able to extend your harvest even longer.

To figure when to plant for a late harvest, check out the days to harvest listed on the seed packet of vegetables you'd like to grow. Count back from your desired harvest date; then add 10 days to take into account the slower growth rate as days shorten and cool. Add on an additional week or so for the harvest period and you'll arrive at your planting date. In short-season areas, you may find you need to sow seeds of some kinds and varieties of greens in late summer in order to give plants time to mature before cold weather arrives.

Spinach: Popeye's pick makes a great fall crop in most areas. Spinach relishes the cooler weather, and decreasing daylengths don't trigger bolting. In cold winter areas, sow seeds about 8 weeks before hard frosts (below 28 degrees F) are due to hit. Southern gardeners can usually harvest spinach through December or even later in the warmest areas. Make successive sowings every 2-3 weeks throughout the fall.

You can even set things up in fall to enjoy an extra early harvest the following spring. Plant spinach seeds in the late fall, just before the ground freezes. The seeds will lie dormant in the soil over the winter and sprout as soon as conditions are right in the spring. Often they'll germinate and grow when the ground is still too wet to be worked, which can delay spring planting. You may get a lower germination rate, depending on weather conditions over the winter, but if you're willing to take a bit of a gamble, you can often enjoy an extra-early spinach harvest from fall-sown seeds. Another technique for early harvests is to sow spinach seeds about 6 weeks before your expected frost in the fall. The plants will germinate and make a little bit of growth. Before hard frost hits, cover baby plants with heavy-weight row cover fabric and keep the protection on over the winter. Remove the covering in early spring as plants come back into active growth. This will often give you about a six week jump on a spring-planted crop.

Arugula: This peppery green is equally delicious in a salad or a stir-fry. Unlike spring-planted arugula, a fall crop won't bolt as readily and become bitter and unpalatable. Sow seeds every couple of weeks from late summer until about a month before hard frost. Give plants a steady supply of water for the best flavor. Harvest when leaves are 3-4 inches tall for the mildest flavor.

Lettuce: Choose quick-maturing leaf and butterhead varieties. Begin planting in late summer and make successive sowings every couple of weeks, up until about 6 weeks before your hard frost date. If seeds are sown in a cold frame or under row covers, even northern gardeners may be able to add homegrown lettuce to holiday salads. Seeds planted in late summer, when the soil is still hot, may not germinate well. Cool the soil by shading the lettuce bed for a week before planting or start seeds indoors under lights where it’s cooler and then transplant the seedlings to the garden.

Corn Salad: Also called mache, this mild-tasting green is one of the hardiest you can grow. For fall harvests, begin planting successive crops in late summer, continuing until early to mid- fall. Seeds may be slow to germinate (10-14 days). If given some protection, corn salad may be harvested into the winter. Plants may even overwinter for an extra-early spring crop.

Swiss chard: In most areas, start seeds about 2 months before the fall frost date. In mild-winters areas such as the Deep South, Southwest, and southern California, nutritious chard can be sown in late summer and fall for late fall and winter harvest. Gardeners throughout the Southeast may able to harvest well into the winter if plants are protected by low tunnels or cold frames. Thin to 2 inches apart for a harvest of “baby” leaves. If you want to harvest mature leaves, space seedlings 6-8 inches apart.

Mustard: Spice up salads with the peppery bite of easy-to-grow baby mustard greens. In late summer to mid-fall, plant either in a cold frame or directly in the garden. Scatter seeds thinly in a wide row, covering with ¼ to ½ inch of soil. Harvest by cutting entire plants at the soil level when they are 3-6 inches tall.

Kale and collards: These hardy crops shrug off frosty weather. To harvest at full maturity, sow seeds about 10-12 weeks before fall frost. To pick kale as baby greens for salads, sow seeds in succession from late summer to mid fall, depending on your climate. Baby collard greens have a somewhat tougher texture that tastes best cooked, in stir-fries or soups.

Asian greens: This category encompasses a wide variety of greens that have come to us from across the Pacific. Bok choy is one of the most familiar. Start seeds about 8 weeks before the fall frost date. Thin according to whether you are growing baby or full size plants. There are many other kinds of Asian green to explore. Mizuna is a mild Asian green with a slightly peppery taste that can be added to salads or stir-fries. Sow seeds of this hardy crop in late summer to early fall. Thin seedlings to about 6 inches apart when they are a few inches high. Taht soi (also spelled tatsoi)  is another cold hardy Asian green with a mild mustardy flavor and slightly crunchy texture. For fall crops, plant from midsummer up to about 5 weeks before your hard frost date.

Troubleshooting Fall Greens

Flea Beetles: These small, black beetles that jump like fleas can be problematic on just about all kinds of greens, chewing numerous small holes in the leaves. The easiest way to foil these pests is to cover crops with floating row covers as soon as seeds are sown or young plants set out in the garden.

Caterpillars: Cabbageworms and cabbage loopers may infest kale and collards, chewing holes in the leaves. In general, however, they are not as attracted to these greens as they are to other members of the cabbage family. Floating row covers will prevent egg-laying by the female butterfly and moth adults.

Cabbage Aphids:  These small, gray, pear-shaped insects are often found in large numbers toward the end of the growing season on cabbage family members such as kale, collards, bok choy, and mustard. They feed by sucking out the plants’ sap, causing leaves to become yellow and distorted. Knocking aphids off the leaves with a strong stream of water from a hose will take care of small infestations. If aphids are numerous, insecticidal soap sprays will help with control. Encourage beneficial insect predators by planting nectar-providing flowers nearby.

Poor Germination: The seeds of greens, especially spinach and lettuce, may germinate poorly in hot soil when direct-sown in summer. Starting seeds indoors under lights and transplanting to the garden when seedlings are a few inches tall is one way to get around this problem.

Harvesting Fall Greens

Begin harvesting greens when they reach useable size — 3-6 inches. Pick off outer leaves individually and let the inner leaves continue to grow for a continued harvest. Let plants continue to grow if you want to harvest full-size leaves. Many greens such as lettuce, mustard, mizuna, and arugula can also be cut off an inch or two above the soil level when plants are 4-6 inches tall. Give the cut stubs a boost with a dose of soluble fertilizer and the plants will regrow, giving you a second harvest in another 3-4 weeks.

Delve into the delights of Asian greens with this recipe for Crunchy Bok Choy Slaw from Eating Well.

Fun Facts

• While today dark leafy greens are regularly touted for their nutritional benefits, the cartoon character Popeye may have been the first greens booster! Popeye credited his bulging muscles, virtuoso dancing, and piano playing skills to his eating canfuls of spinach. The Popeye cartoons were so popular in the 1930s that the sale of spinach in the U.S increased by 33%!
• Think that arugula is hard to pronounce? No problem! Just pick another name. This nutritious green goes by a variety of common names, including rocket, colewort, roquette, and rucola. Its scientific name, by the way, is Eruca sativa.
• The name mizuna comes from two Japanese words, “mizu,” meaning water, and “nu,” meaning mustard plant. Supposedly this relates to the fact that in Japan mizuna is grown in fields that the flooded shallowly for irrigation.