The harvest season of tomatoes, peppers and corn may be coming to a close, but that doesn't mean it's time to hang up your hoe! Fall is a great time to grow many kinds of greens, including lettuce, mustard, collards and specialty greens such as arugula. All of these crops grow well in the cooler fall weather and, depending on where you garden, may provide fresh harvests even through the winter months.
Not only are greens delicious, they are among the most healthful crops you can grow. These nutritional powerhouses are full of vitamins, minerals and anti-oxidants. In fact the USDA recommends that we all eat at least three cups of leafy greens a week. And greens are easy to grow and take up little garden space- you can tuck them into beds as earlier crops finish up, sneak a little space from a flower bed, or even sow some seeds in containers on your deck.
Lettuce probably comes to mind first when we think of greens and there are many varieties of this salad staple that will flourish in the fall garden. Butterhead and romaine lettuces withstand cold weather well, while leafy varieties harvested early as 'baby lettuce" grow quickly enough for even northern gardeners to reap a late-season crop.
For top nutritional benefits, deep green collards are the crop to grow and you'll find their flavor improved by a light frost. Specialty greens like arugula and mache are two of the cold hardiest greens around, providing produce fresh from the garden long after other vegetables are done for the season.,/p>
Lettuce This is a great fall crop because it grows well when soil temperatures are cool and daylegths are getting shorter. In fact, one problem you may encounter is poor germination due to high soil temperature when you direact seed in late summer and early fall, especially in southern gardens. One way around this problem is to sow seeds indoors in flats or pots, transplanting seedlings to the garden when they are a few inches tall.,/p>
In northern gardens, you can begin seeding your fall lettuce in early August, making twice weekly succession plantings up until about mid-October for quick-maturing leafy varieties. Gardeners in the central parts of the country can begin sowing seeds in early September, continuing with succession plantings until frosts come. And in southern areas, you may be able to plant succession crops from October through March.
Collards Tolerant of cool conditions, collards make a good fall crop in many parts of the country. Sow seeds in late summer or early fall, about 10 weeks before the first expected fall frost date, thinning plants first to 6 inches apart and then to 12 to 18 inch spacing so they have plenty of room to develop. You can begin harvesting leaves of collards as soon as they are big enough to use, although cool weather and light frost will improve their flavor.
Arugula Cool weather will also keep this spicy salad green on the mild side. Begin sowing this quick-maturing crop in late summer, continuing up until about a month before the fall frost date. Start harvesting as soon as the leaves reach useful size and use your harvest quickly. Arugula doesn't keep well in the refrigerator after picking.
Corn Salad Also known as mache, this mild-tasting green is extremely hardy, so make successive sowings every 2 weeks up until around the time of the first frost date. You can harvest individual leaves or the entire plant by cutting off the plants at ground level. You may get a second harvest from the cut stub.
Mustard This easy to grow, quick maturing green makes a good fall crop from a late summer or early fall sowing. Like arugula, its taste gets milder as the weather cools. Begin harvesting as soon as leaves are large enough to use or let it mature and cut the entire plant. Like arugula, mustards don't keep well after picking. Mizuna is a mild-tasting Japanese mustard with similar cultural requirements.
Pak-Choy The name of this mild-tasting green means "white vegetable" in Chinese, a reference to its crunchy, celery-like, white stems topped with rounded green leaves. Growing best in cool weather, it matures quickly and can be planted up to 5 to 6 weeks before the first fall frost date. Pick off individual stalks or cut the entire plant off 2 inches from the ground. Be sure to keep plants well watered as drought-stressed plants may bolt to seed.
Mesclun This refers to a mixture of greens, rather than one particular kind. Make successive sowings by broadcasting seeds in wide rows. Since the greens are cut when they are small and tender, seeds can be sown as late as 2 to 3 weeks before the first fall frost. Harvest greens when they are 4 to 5 inches high by cutting with scissors about an inch above the ground. You'll often get a second or even a third crop from one planting.
You can extend the harvest season of all of these greens if you give them some protection from cold temperatures. Floating row covers provide defense against light frosts. If you want to garden late into the season, consider planting in a cold frame.
Q:I live in in zone 4 and want to grow lettuce and other greens in my well-insulated cold frame. How long can I do this? Can I add a light bulb, a string of Christmas lights or other heating device and continue to grow greens through a Minnesota winter?
A: Depending on how well insulated your cold frame is, the microclimate for its location, and on the weather, you should be able to keep cold tolerant greens growing for quite a while into the cold weather. Some may even slow down almost completely and then start growing again in very early spring. You are right in thinking that a simple heat source such as a light bulb can extend the season significantly. Whatever you use for heat should be of good quality and made for long term operation to make sure it is as safe as possible; there are in fact heating cables made for such a purpose. In the olden days gardeners would build a cold frame over what was essentially a hot manure pile and capture the heat from that -- these days we have more options!