Growing edible perennials along with annuals in your garden adds diversity and beauty.
PHOTO: BETHANN WEICK
Suppose a new agricultural breakthrough promised higher yields, a longer growing season and much less work. These claims can become real benefits for those willing to make a change to a way of gardening that more closely mimics nature.
Nature’s ecosystems always include not only annual vegetables, but also perennials — edible roots, shoots, leaves, flowers and fruits that produce year after year. Besides fruit-bearing trees and shrubs, more than 100 species of perennial vegetables grow well in North America.
By growing perennials, you’ll create a more diverse garden that ultimately needs less from you: You’ll spend less time working and more time harvesting.
“It’s as close to zero-work gardening as you can get,” says Eric Toensmeier, author of Perennial Vegetables. “Our perennial vegetable beds planted 11 years ago still bear food, and all we do is add compost and mulch once a year.”
What’s more, growing perennials extends the harvest season without a greenhouse, cold frame or other device. You can harvest Jerusalem artichokes all winter as long as you mulch enough to keep the ground from freezing.
“Some perennial crops, such as sorrel, are up and ready to eat in March when the snow is melting,” says Toensmeier, who gardens in Massachusetts. “Most of our springtime food harvest comes from perennials. By the time they’re finished, the annual vegetables are coming in.”
Growing perennial vegetables doesn’t mean giving up tomatoes, peppers and other annual crops. You can experience the amazing benefits of perennial edibles simply by rethinking your existing garden plan and pioneering new, unused areas of your landscape.
3 Ways to Incorporate Garden Perennials
Design and planning are critical parts of “perennializing” your food garden: After your new perennial edibles have put down roots, they’ll be set for years to come. There are three basic design approaches:
1. Push the Envelope. “One method to begin perennial edible gardening is to expand the edges of an already established garden,” says Bethann Weick, garden educator at D Acres, an organic permaculture farm and educational homestead in Dorchester, N.H. Perennial vegetables do well in beds devoted only to perennials because their extensive root systems grow undisturbed by digging and cultivating. However, interplanting with annuals can also be a successful strategy and one way to control erosion in your perennial garden.
To expand your garden’s edges, hand-dig or till a 3- to 4-foot-wide perimeter bed on one or more sides. Or, if you’re willing to wait a year to plant, follow Weick’s easy sheet mulch method to prepare the site: “Cover your lawn with four layers of cardboard, and top that with a thick layer of wood chips,” she says. “Place compost beneath the cardboard layers for additional fertility. Within a year, the grass will die and the mulch will become rich organic matter ready for planting.” Other locally available mulch materials work equally well, Weick says. For instance, thick layers of newspaper could be topped with shredded leaves or grass clippings.
If space or conditions won’t allow you to expand your garden’s edges, you can experiment and create a perennial vegetable border within the bounds of your existing vegetable garden.
2. Dive into Edible Landscaping. If you already grow a perennial ornamental border or foundation shrubs, consider integrating some perennial vegetables, such as sea kale or sorrel. Many have attractive leaves or flowers, and they won’t become so aggressive that they overtake ornamentals. If your gardening space is limited, try growing perennial vegetables — especially greens — in containers.
Take advantage of currently unused areas of your landscape, matching the conditions to the appropriate perennial edibles.
“One of the things I love about growing these foods is that there are different ones for different niches,” says Toensmeier. “Not all require full sun and loamy soil the way most annual vegetables do. You can grow many perennial greens and herbs — such as wild leeks — on the shady north side of the house, below trees, in a wet site or in other unused areas of your property.”
3. Pioneer a Plant Community. If you’re already growing perennial vegetables and want to take garden diversification to the next level, consider permaculture gardening. Like nature’s ecosystems, this approach promotes greater partnerships between plants, soil, insects and wildlife. In permaculture designs, edible vegetables, herbs, fruiting shrubs and vines grow as an understory to taller fruit and nut trees. The technique is sometimes called “layering.”
Weick suggests a five-year plan for gardeners who want to begin layering their landscape with edibles. “In the first year, plant fruit trees as the outposts. That same year and over the next several years, use the sheet mulch technique to prepare planting areas beneath the trees for the understory plants,” she says. Sheet mulch a 2- to 3-foot-radius area around each fruit tree the first year and gradually increase the mulched area as the trees grow. After the first year, you can begin planting the mulched area with perennial vegetables, fruiting shrubs and vines. (For more on this method, see “Permaculture Gardening: A Natural Way to Grow” further along in this article.)
10 Best Perennials
Based on expert recommendations, the following are widely adapted perennial vegetables selected for their flavor, productivity and versatility. Be sure and see photos of many of the perennial vegetables described below in the Image Gallery.
1. Ramps, or Wild Leeks (Allium tricoccum). This onion relative grows wild in deciduous forests east of the Mississippi, emerging in spring. Leaves and bulbs are both edible. Grow in a shady border in moist loam, or naturalize beneath trees. Hardy to Zone 4.
2. Groundnut (Apios Americana). Native to eastern North America, this nitrogen-fixing, 6-foot vine bears high-protein tubers that taste like nutty-flavored potatoes. Grow the vines as Native Americans did: near a shrub (as support) in a moist site that receives full sun or partial shade. Harvest in fall. Hardy to Zone 3.
3. Asparagus (Asparagus officinalis). This familiar plant is long-lived and productive, bearing delicious green or purple shoots in spring. Asparagus thrives in full sun and moist, well-drained soil. For best production, plant male hybrids. Hardy to Zone 3.
4. Good King Henry (Chenopodium bonus-henricus). A traditional European vegetable known for its tasty shoots, leaves and flower buds, this spinach relative grows in full sun or partial shade and moist, well-drained soil. Plant seeds in compost-enriched soil, and harvest the tender shoots in spring. Hardy to Zone 3.
5. Sea Kale (Crambe maritime). Sometimes grown as an ornamental, this coastal native bears gray-blue leaves and white flowers on 3-foot-tall plants. Cover the plants in spring and harvest the blanched, hazelnut-flavored shoots when they are about 6 inches tall. The young leaves and flowers are edible, too. Plant nicked seeds in moist, well-drained soil in full sun. Hardy to Zone 4.
6. Jerusalem Artichoke, or Sunchoke (Helianthus tuberosus). Grown by Native Americans, sunchokes bear sunflowerlike blooms on 6- to 12-foot stems. The crisp, sweet tuber can be eaten raw and used like potatoes. An added bonus: Sunchokes attract beneficial insects. Plant tubers in full sun and well-drained soil. Harvest in fall and winter. Hardy to Zone 2.
7. Lovage (Levisticum officinale). The young leaves and stems of this 6-foot-tall perennial are an excellent substitute for celery in springtime soups. The seeds and roots are also edible, and the umbel flowers attract beneficial insects. Lovage thrives in average garden soil, in sun or partial shade. Hardy to Zone 4.
8. Rhubarb (Rheum x cultorum). Although most people think of rhubarb for dessert, the reddish stems have a long history of use as a vegetable in soups in Asia. Caution: Don’t eat the leaves or roots, which are poisonous. Plant rhubarb roots in full sun and rich, well-drained soil. Harvest in spring. Hardy to Zone 1.
9. French Sorrel (Rumex acetosa). The lance-shaped leaves of sorrel add a wonderful, lemony tang to salads and soups, and they can be harvested from early spring to late fall. Look for sorrel transplants in the herbs section at your local nursery. Sorrel grows in sun or shade and average soil. Hardy to Zone 3.
10. Crosnes, or Chinese Artichoke (Stachys affinis). Also known as mintroot, this little-known mint relative sets out runners that form a dense, 12-inch-high ground cover. The small, white tubers are crisp and sweet, and add a great crunch to salads. Harvest the tubers annually for best plant growth (just leave a few for the following year). Grow crosnes in full sun or partial shade in well-drained soil. Hardy to Zone 5. (For more info, see Crunch a Bunch of Crosnes.)
Happy Returns From Perennial Gardens
Keeping your perennial plantings going isn’t much different from caring for annual crops. In fact, after they’ve been established, perennial vegetables practically care for themselves. “These plants have deeper root systems, so they need fewer outside resources — such as fertilizer and water — than annual crops usually need,” says Toensmeier.
Giving the plants a strong start is key. Before planting, dig compost and other necessary amendments deeply into the soil, as you would for perennial flowers. Give aggressive perennials, such as Jerusalem artichokes or self-seeding garlic chives, their own bed so they won’t overtake more modest growers. Be especially sure to stay on top of weeds the first year or two until your perennials have spread out above and below the ground. Mulch the beds with a generous layer of compost, wood chips or shredded leaves early on. “You also can experiment with an edible ground cover, such as violets or wild strawberries,” Toensmeier says.
With its increased diversity, your garden should have fewer insect and disease problems. For added insurance against pests, Weick interplants calendula and other flowering plants to attract beneficial insects (for more on attracting beneficials, see Enlist Beneficial Insects for Natural Pest Control). Otherwise, maintenance is simple. Feed perennials annually with compost or another organic fertilizer, replenish the mulch each spring, and remove any weeds that sneak in. Consider these measures a small investment, because “planting perennial edibles is planting for the future,” Weick says. “Over time, you’ll put in less work and harvest more food, while building diversity and stewarding the land for future generations.”
Permaculture Gardening: A Natural Way to Grow
Developed by Australians Bill Mollison and David Holmgren in the 1970s, permaculture is “an ecological design system for sustainability in all aspects of human endeavor,” according to the Permaculture Institute in Santa Fe, N.M. The approach is modeled on the structure and relationships of natural ecosystems, and the principles can be applied to growing food, building homes and communities, and more. Learn more at the Permaculture Institute website and in our Permaculture blog, to which permaculture gardener and educator Bethann Weick regularly contributes.
Getting Started With Perennial Vegetables
PLANTS AND SEEDS
Some perennial vegetables can be difficult to find at local garden centers. Check out these mail-order suppliers, and use our Seed and Plant Finder to locate additional sources.
Goodwin Creek Gardens: Williams, Ore.
Oikos Tree Crops: Kalamazoo, Mich.
Permaculture Nursery: Food Forest Farm; Holyoke, Mass.
Tripple Brook Farm: Southampton, Mass.
Gaia’s Garden: A Guide to Home-Scale Permaculture by Toby Hemenway
Perennial Vegetables by Eric Toensmeier
Apios Institute for Regenerative Perennial Agriculture
Plants for a Future
Vicki Mattern is a contributing editor for MOTHER EARTH NEWS magazine, book editor and freelance magazine writer. She has edited or co-authored seven books on gardening, and lives and works from her home in northwestern Montana. You can find Vicki on Google+.