by Sally Colby
Many experienced vegetable growers maintain at least a few perennial crops such as asparagus, rhubarb, garlic and horseradish. Bill Davison, Extension educator at the University of Illinois, said there are more choices when it comes to perennials.
“One of the main reasons to consider growing perennials is there’s relatively little investment,” said Davison. “You can get years of harvest, and they tend to be tougher and more resilient.”
Davison said most perennial vegetable crops require little care after establishment, and dropped leaves and other vegetative matter at the end of the growing season help build organic matter. Perennial vegetables help extend the growing season – they’re often the first to green up in spring and will be ahead of annuals. Large perennials such as fruit trees help with carbon sequestration and provide habitat for beneficial insects.
As with any crop, perennial vegetables come with some challenges. Many perennials are aggressive growers and can be difficult to manage. There’s also risk of disease that can’t be managed with a multi-year crop rotation. “Because these plants are rooted in place and you can’t rotate them, you have to be more aware and careful about managing disease,” said Davison. “It can also take years to establish a crop.”
Perennial vegetables offer a variety of edible portions, including leaves, shoots, fruits used as vegetables, edible pods and beans, edible flowers and flower buds, aerial root crops and colony-forming root crops. Davison said while annual crops are often selected for flavor and preferences, that isn’t always possible with perennials. Because customers tend to gravitate toward what they already know, marketing can be a challenge. However, creative growers can help open-minded customers develop a taste for new and different vegetables.
An important consideration prior to committing to a perennial vegetable crop is site preparation. “They’re going to be there a long time, so take time to get the pH right and balance nutrients,” said Davison. “Make sure you don’t have perennial weeds like Canada thistle and bindweed because it’ll be much harder to deal with them later. Try to remove [soil] compaction so you get the full benefit of these plants accessing deeper reaches of the soil and nutrients stored there, and the drought tolerance they get from being more deeply rooted.”
Because these are long-term crops, Davison said it’s worth looking into irrigation the first season to get them started. “After that, their needs diminish,” he said. “If plants look like they’re doing well, you don’t necessarily have to irrigate, especially if you can mulch them. If they looked stressed, it’s worth investing in giving them enough water to get them through the first year.”
Davison described some of options for growers interested in perennial vegetables. “There’s tremendous potential with alliums,” he said. “If you’re already a grower selling to markets, it’s pretty easy to add some diversity with alliums.” Davison explained the potato onion, a relative of shallots that divide underground like potatoes. “You plant a single bulb, and ideally, get a cluster of three- to four-inch onions. They store for up to 12 months, sometimes longer.”
The Egyptian walking onion is a top-setting variety with red bulbs at the top of the plant. “The plant will fall over and will be propagated by those,” said Davison. “These and some of the scallion-type onions can give you very early green onions.” Another perennial allium is Evergreen Hardy White bunching scallion that’s ready in early spring for the start of market season.
Lovage is a celery-like herb with a strong flavor. Davison suggested growers start with a small planting to sample this herb prior to establishing a larger lot. “Make sure your customers like it,” he said. “It’s something you would eat early, when it first leafs out and is more mild. As it matures in summer, it gets stronger. This can get large – six feet tall and quite wide.”
Burdock, not to be confused with the weed of the same name, is a cultivated variety with long roots. Davison said the roots are used for cooking, and for many, burdock roots are part of traditional cuisine. The most challenging aspect of growing burdock is harvest because the roots are so long. It’s best grown in loose, sandy soil.
Davison described skirret as a relative of the carrot that was once commonplace in American home gardens but replaced by potatoes. “The roots are about the size of a pencil,” said Davison. “The small white flowers attract beneficial insects.”
Depending on the variety, chicory is another perennial worth trying, but Davison cautions growers to be mindful of its bitter flavor. He said most Americans don’t like bitter food, but there are ways to moderate the flavor, and chicory can add interesting color and flavor to a greens mix.
Sorrel is another perennial that offers a unique flavor – sour – which doesn’t appeal to everyone. “It’s very early,” said Davison. “It could likely give you the first greens of the season. It’s good for soups because the leaves tend to dissolve.” Sorrel comes in several varieties, including an eye-catching red-veined variety.
Jerusalem artichokes, or sunchokes, are related to sunflowers. “This is a native root crop,” said Davison. “It’s an example of something to be sure you want because it’s hard to get rid of.” Plants reach eight to 10 feet tall, set a lot of tubers and spread. Davison said this perennial is very nutritious but contains inulin, a type of starch that can be hard to digest.
Scorzonera, or black salsify, is a root crop with edible leaves and roots. “The leaves are somewhat like lettuce, and the roots taste similar to oysters,” said Davison. “It’s a cooking root, not something you would eat raw.”
Davison discussed kale, a crop with mixed popularity among growers and consumers. “Kale was a perennial crop in the wild that we domesticated,” he said. “Western Front perennial kale was bred by Pacific Northwest breeder Tim Peters. About half the plants are perennial, and it resembles Red Russian kale.” Davison added this kale would be well-accepted by market customers who are familiar with and like kale.
Runner beans, also called scarlet runners, develop roots that survive to 23 degrees. Plants can live for up to 20 years, but take significant trellising. Davison said they provide green beans, flowers, dry beans and tubers. Scarlet runners are often used as an ornamental and are available in numerous varieties.
Davison said mushrooms are overlooked but potentially profitable. “There’s been a tremendous explosion in availability of different types of mushrooms and information about propagating them,” he said. Logs are managed differently between incubation and the growing period, but it’s fairly easy to learn how to manage the different stages. Mushrooms can be grown outside in a shaded area or added to a high tunnel. Davison added that mushrooms can also be grown on wood chips. “Buy the spawn [inoculated sawdust] and spread it on fresh wood chips,” he said. “Wine cap, oyster and lots of other varieties are being propagated.”