By Eric JB von Wettberg, Sandrine Dincki, Jasmine Hart, and Alexis Yamashita
Did you know that we can eat the shoots, leaves, and flowers of many of the crops we typically grow for seeds or roots? For example, sweet potatoes, well loved by many Americans for their tubers, are prized for their green leaves in many cuisines, such as Cantonese regional Chinese cuisine. Several legumes can also be consumed as leafy greens or shoots, giving growers creative options to design crop rotations or diverse plantings in a variety of settings. Some of our favorite legumes with desirable leafy greens include fava beans (Vicia faba, sometimes known as faba, broad, or horse beans), peas (Pisum sativum), mung beans (Vigna radiata), black-eyed peas (Vigna unguiculata), and fenugreek (Trigonella foenum-graecum).
It is worth putting the spotlight on leafy green legumes because they act as a natural fertilizer. Fertilizer has always been an important expense for organic farmers and gardeners. With increasing tariffs and uncertainty around supply chains, growing your own fertilizer is an important way to manage costs and increase crop diversity. Legumes are uniquely important to organic production because of their capacity to turn the air around us into nitrogen fertilizer for themselves and other crops through symbiotic nitrogen fixation with rhizobia bacteria. We recommend using rhizobia inoculum, typically purchased from a seed supplier, with all legume crops. Inoculum is particularly useful in a soil where a specific legume crop has not been grown before because rhizobia adapted to a particular legume host are likely absent. Rhizobia inoculum applied to seeds will ensure that at least some symbiotic nodules form on the legume roots. Since different legume species tend to associate with distinct strains of rhizobia, many commercial mixes of inoculum contain a suite of rhizobia strains. A grower should select an inoculum designed for the specific legume crop.
To harvest fava as a leafy green while maintaining the potential for seed production, clip the side shoots. Photo by Eric von Wettberg
Fava Beans
Let’s start with fava beans (Vicia faba), an underutilized leafy green legume. Thought to have been first cultivated in the Eastern Mediterranean region, fava beans are multifunctional in their uses as a dry bean, a green bean, an annual forage, and a leafy green. Fava beans are perhaps the best nitrogen fixer among cultivated legumes, although the amount of residual nitrogen that they leave for other crops depends on production conditions (i.e., how much biomass you remove at harvest). To harvest fava shoots while maintaining the potential for seed production, side shoots can be harvested by clipping. Fava beans can be grown as either a spring or a fall/winter crop, depending on the cultivar.
While many commercial cultivars are spring types that should be planted as soils warm (60-65 F) but before summer heat begins, overwintering types that can be planted in the fall are available. Trials performed by the United States Department of Agriculture (USDA) in Pullman, Washington, indicate that these winter types likely lack the hardiness for outdoor production in most of northern New England. However, in a protected setting such as high tunnel, winter favas can provide a winter leafy green crop while also providing ample nitrogen for a summer crop like tomatoes. In a pilot study, conducted in a tunnel last winter at the University of Vermont’s horticultural farm, four USDA gene bank accessions were able to survive without watering through the winter.
Field Peas
Field peas (Pisum sativum) are another legume green with overwintering potential. We have found that Austrian field peas, or vegetable peas with Austrian field pea genetic heritage, can tolerate Zone 4 winter conditions if planted around mid-September. Carrying overwintered peas to maturity often interferes with summer cropping operations, as they mature in mid-June in Zone 4 and 5. However, if pea shoots are harvested in the fall or early spring, one gets the benefit of soil stabilization and nitrogen fixation as well as a harvestable green that is ready before the spring planting season.
Mung Beans and Black-Eyed Peas
Next, we highlight mung beans (Vigna radiata) and black-eyed peas (or cowpeas, V. unguiculata) together because they make two wonderful summer leafy greens that can be cooked in identical ways. Mung beans are familiar to many Americans as bean sprouts in Southeast and East Asian cuisines, while black-eyed peas are often consumed as whole beans. What may be less widely known in the United States is that their leaves are traditionally eaten boiled or blanched in cuisines from Western Africa to East Asia, similar to spinach.
Both crops are tropical, requiring warm soil temperatures (65 F and above) to germinate and lacking cold tolerance for spring or fall conditions. They are also historically difficult to grow to seed in short New England summers. But rising temperatures make them easier to produce. Furthermore, mung beans in particular have a very short growth duration (100 days for many cultivars), allowing them to be grown from seed to seed in a summer. Furthermore, it is possible to expand the growing window significantly by harvesting leaves from immature plants.
We have tested both crops in a range of settings. When under-sowing either crop as a companion to silage corn, where their high protein content could increase feed value, a Sustainable Agriculture Research and Education (SARE) project found that these crops thrive in humid summer conditions, benefitting from the shade of other crops in a crowded setting. While tender greens of both mung beans and black-eyed peas can be eaten fresh, many of the cultural traditions around cooking leaves of these legumes involve sauteing, boiling, or fermenting them. Similar approaches can be used with leaves of common beans (Phaseolus vulgaris), scarlet runner beans (P. coccineus), and lima beans (P. lunatus), which are also edible.
Fenugreek and Other Legumes
Another tasty leafy legume is fenugreek (Trigonella foenum-graecum). Fenugreek is often used as a curry spice, known as methi in Hindi, that can be used either as a seed or leaf. With a ground-hugging growth form, it can be grown in a pot like other summer herbs. Like the warmth-loving black-eyed peas, fenugreek seeds germinate above 65 F. With an origin in semi-arid climates of Western and Southern Asia, it tends to thrive in drier soils.
There are other legumes with edible leaves that deserve some mention, as they are very common in New England. Alfalfa is among the most widely grown crops in North America, being known as the “queen of forages” among hay producers. Almost all alfalfa is consumed by livestock. Only a tiny fraction of all the alfalfa produced is distributed for alfalfa sprouts, which are much smaller than the sprouts of mung beans. We don’t recommend eating the leaves of whole alfalfa plants, finding the foliage less tasty. The leaves do not cook well in our limited experience, shriveling and giving off-flavors.
Clovers, another genus of forage crops, are mostly edible. Clover flowers can add a unique twist to a summer salad. However, some clovers, particularly white clovers, can contain cyanogenic glycosides that are poisonous and may not fully break down with cooking. Like alfalfa, mature clover leaves also do not cook well in our experience.
Cooking with Legume Greens
Leafy greens of any plant will always be more tender when newly emerged and on younger shoots. Cooking will soften the leaves as well as alter flavor.
Keep in mind that some anti-nutritional factors stored in the leaves like phytic acid, lectins, or tannins are degraded by cooking, while others, like the ODAP (β-N-oxalyl-l-α,β-diaminopropionic acid) neurotoxins in grass pea (Lathyrus sativum) or the pyrrolizidine alkaloids in many varieties of Sunn hemp (Crotalaria juncea), may not be completely destroyed. Other ways of preparing food, like fermentation, can also reduce some anti-nutritional factors but are not effective at breaking down some compounds like the cyanogenic glycosides of some clovers.
If you’re feeling inspired to experiment with legume leaves, explore some recipe ideas from around the world such as: fava bean pesto, methi (fresh fenugreek) rotis (India), dòu miáo (China) with snow pea shoots, or munyemba (Zimbabwe) and eboo (Uganda) with cowpea leaves.
Dr. Eric JB von Wettberg is a professor, department chair, and administrator at the University of Vermont College of Agricultural and Life Sciences and the Vermont Agricultural Experiment Station, where he leads the Crop Genetic Heritage Laboratory, and is happy to answer any question related to legumes. Sandrine Dincki and Jasmine Hart are graduate students at the UVM Department of Agriculture, Landscape, and Environment. Alexis Yamashita is a graduate student in the Food Systems Doctoral program at UVM.
This article was originally published in the summer 2025 issue of The Maine Organic Farmer & Gardener.
