A Guide to Vegetable Legumes

Longtime Maine farmer and homesteader Will Bonsall shares his knowledge and experience with different vegetable legumes.

Vegetable Legumes

Vegetable legume plants—beans and peas—are able to host bacteria that converts atmospheric nitrogen (N2) into nitrate (NO3). The legume plants then use the converted nitrate to build proteins.

Photo by Dani Vincek/Fotolia

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In Will Bonsall's Essential Guide to Radical, Self-Reliant Gardening, author Will Bonsall maintains that to achieve real wealth we first need to understand the economy of the land, to realize that things that might make sense economically don't always make sense ecologically, and vice versa. The marketplace distorts our values, and our modern dependence on petroleum in particular presents a serious barrier to creating a truly sustainable agriculture. Bonsall draws upon the fertility of on-farm plant materials: compost, green manures, perennial grasses, and forest products like leaves and ramial wood chips. And he grows and harvests a diversity of crops from both cultivated and perennial plants: vegetables, grains, pulses, oilseeds, fruits and nuts―even uncommon but useful permaculture plants like groundnut. In a friendly, almost conversational way, Bonsall imparts a wealth of knowledge drawn from his more than forty years of farming experience.

Vegetable Legumes

Vegetable legume plants—beans and peas—are distinguished by their tendency to host certain soil bacteria that have the magical ability to convert atmospheric nitrogen (N2) into nitrate (NO3). Legume plants can use the nitrate to build proteins and stuff. Those plant proteins (which I tend to think of as dietary nitrogen) in turn feed us; indeed some of their amino acids are not adequately found in grasses or other plant foods. I think it is only too cool that we benefit from this major source of protein from plants that do not even make the protein themselves, but rely in turn on yet another level of life. We may be a predator of the legumes, but their relationship with the bacteria seems somewhat more cooperative. The rhizobacterial (that’s techno-speak for “root-cooties”) colonies are at first glance parasitic—they feed on surplus sugars in the root sap—but they pay very well for their keep by performing that nitrogen trick. Both parties seem well content with the arrangement, so who are we to naysay?

In order to make this miracle appear out of thin air, the bean, or rather the bacteria, must have access to that air, and since they cannot climb up out of the soil to get it, the air must be brought to them. Therefore abundant organic matter in the soil is critical, not so much because of any particular ingredient in it, but for its role in allowing air to enter the soil and remain. If, however, you reduce the humus level and add lots of nitrogen fertilizer, you will gain nothing and lose a lot. Legumes in general do not appreciate being spoon-fed; they prefer to make their own.

Despite their importance in the nitrogen/nitrate/protein connexion, not all of the vegetable legumes can be properly thought of as protein sources. In the case of green beans and snow peas, the pod is the food part, and that part, I suspect, is not much higher in protein than, say, a pepper. As I understand it, it is in the mature dried seed—the pea or bean or lentil—that the concentrated protein is found. But we also eat the full-sized but immature seed of many legumes, such as table peas, shelled beans, runner beans, favas, and vegetable soybeans (aka edamame). These legumes are still among the most nutritionally dense vegetables. They may have less protein than their mature forms, but that protein is much more hydrolyzed (chemically bound up with water) and thus much easier to digest and assimilate.

The combination of comparative richness with easy digestibility makes most of the legume veggies uniquely suitable for making dips and spreads resembling guacamole.

The Old World legume crops—peas, chickpeas, and favas—are extremely ancient domesticates and all very cold-hardy. Like all legumes, they enjoy lots of alkaline minerals: potassium, calcium, and magnesium. However, because I plant my vegetable legumes in among other vegetables that I feed with high-mineral compost, the legumes get all the minerals they need.

The cold-hardiness of the Old World legumes makes them particularly suitable for companioning with compact, equally cold-hardy vegetables. By “compact” I mean the largely biennial alliums, brassicas, umbels, and composites (lettuces, chicories, salsify). These all mesh very well with the legumes in terms of fertility and spatial demands. The taller New World legumes—pole beans and runner beans—are very frost-tender and shade casting, so they work better as intercrops with sunflowers and amaranth.

I use some legumes in two or three forms—as both fresh vegetables and dried pulses—and I risk some redundancy in describing separately how I grow each type, but that being said let’s now consider each vegetable legume in its turn.

Peas

Peas are mainly known as a fresh vegetable, one of the foods kids love to hate. Actually even as a kid I had really perverted tastes, because I loved peas, spinach, lima beans, and broccoli whenever they were served; I even liked canned peas. After I went “back-to-the-land” (not that I came from there in the first place), and had no ability to freeze stuff, fresh peas became a seasonal treat that we longed for during the rest of the year, like corn-on-the-cob. We could and did blanch and dehydrate fresh-shelled peas and snow peas. Frozen snap peas just don’t cut it, so we still enjoy those in season only.

Our great-grandparents had a similar experience: Before Clarence Birdseye pulled a fish out of Newfoundland waters and discovered flash-freezing, most pea eating was in the form of split pea soup, with the special luxury of fresh shelled peas in July. In fact many of the older shell pea varieties, like Early Alaska, were originally round-seeded field, or soup, peas, which also worked well if picked immature. However, those varieties are quicker to go starchy, so modern tastes have leaned toward the wrinkle-seeded types. The older types have not gone away but have found a niche as canning peas, as they hold up better through processing.

At the opposite extreme are the petit pois or “little peas.” Now I learned petit pois to refer to any wrinkle-seeded green shell pea, as opposed to the field peas; however it has come to mean a more specific type of tiny tender pea that is used quite immature and whose seed is squat and flattened like a tuna fish can. These are all the rage in the sniffy gourmet set, but I prefer the more robust flavour of regular fresh shell peas like Green Arrow and its many selections.

A word about the “leafless” or tendril-type pea varieties: There are a number of varieties (such as Novella) that have been bred for an exceptionally high number of tangly tendrils. Some folks like to grow these, figuring that the tight-tangled mass of plants will support itself (which it will) and allow them to say goodbye to fussing with hex-wire fence or weaving brush. The problem is that all those tendrils are modified leaves, not true leaves—they grow at the expense of chlorophyll, and that spells reduced sugar. Unless you prefer starchy peas to sweet, “leafless” peas offer no advantages. But if a pea named Bikini turns you on, go right ahead and grow all you want.

Edible-podded peas consist of two types: snow peas, whose immature pods are eaten before the peas begin to fill out, and snap peas, a more recent innovation that can be eaten when the peas are full-sized but the pods are still tender and sweet. All edible-podded peas lack the parchment or papery layer that lines the pods of common peas and makes them inedible.

Snow peas. The snow peas are further divided into the small-podded varieties, and the carouby (“pod” in French; cf. “carob”) or cabbage peas, which can grow quite large and still be excellent eating, although they may develop a dorsal string that wants removing; the pod remains quite fibre-free except for that string. Given the fact that cabbage peas can grow much bigger without becoming useless, why would anyone grow the small-podded types? In my experience the latter produce a lot more pods, especially if you keep them picked, plus they can be cooked and eaten whole, whereas the large ones are best cut up like green beans. I don’t prefer one over the other; I grow them both and use them in different ways.

I do prefer tall peas over short, for the sake of yield, although shorter varieties are a few days earlier. Since I now have a freezer, yield is more important than season extension. The things that makes peas so cold-hardy—all those sugars and cell salts—also make them freeze superbly. At this point my favourite cabbage pea is Carouby de Maussane and my favourite small-podded variety is China Snow.

Most snow pea varieties, on the other hand, have smooth seeds and can be salvaged for soup peas, though that is not their best use. Many of the snow pea varieties have beautiful purple blossoms and olive-brown seed with purple speckling. These pigments (tannins) impart a strong flavour when cooked as soup peas, which some may find either pleasant or objectionable.

Some friends once boasted that they only grew snow peas because they felt that shell peas are too wasteful. They used snow peas for all three uses: When the pods got too old they shelled out the peas, and if these went by they used them as dry peas. Well, I cannot impugn their taste—I mean, taste is taste, after all—but it seems to me they were settling for second best (or third . . .) in using varieties for their unintended use. One of many reasons I like to avoid the marketplace is so that I can afford to eat the very best, or what I like best, rather than what some system can offer me.

Snap peas. Snap peas seem in some ways superior to snow peas in that you have the filled-out peas, and thus presumably more protein. They are big and dense and seem less wasteful; they are a delectable raw snack that even pea-hating kids love. All good reasons to grow them, but no more than you will use fresh, for they do not freeze or can well; whatever you don’t use fresh will go to waste, beyond what you need for seed. Whereas some shell pea varieties (like Alaska) have smooth seeds that go starchy and therefore can double as soup peas, snap peas are wrinkle-seeded and useless for anything else.

Growing peas. Studies have demonstrated that peas sown too early will mature early (obviously) but will yield somewhat less for the rest of the season. Peas planted a week later when soil is a bit warmer may crop slightly later, but not necessarily a week later, as the warmer soil enables them to catch up somewhat. But the important difference is that the later peas will yield better overall. At some point the advantage disappears, because late peas suffer from various forms of heat stress. Of course, successive sowings are the best way to extend fresh-pea season, but as the weather turns hotter and drier, blossoms tend to abort and pink root rot may set in. Heavy mulch may help the latter problem, but it doesn’t affect air temperature much. I have used heat-tolerant varieties like Wando, or early-planted late-maturing varieties like Tall Telephone, but mostly I just shift over to eating green beans and green runner beans.

As for fall cropping, planting shell peas for a fall crop doesn’t work well for me; the timing is wrong and the plants usually suffer from powdery mildew. Snow peas will grow well in fall for me, however, perhaps because I can plant them as late as July 10 and still expect a fine crop, ripening in cooler weather.

For supporting my peas I used to build a trellis of woven alder brush, very attractive, very organic, and very effective at holding vines upright with optimal spreading for maximum production. However, since I’m often trying to do too many things and have too little help, I have “relapsed” into using chicken-wire fencing. That works almost as well; it just isn’t wicked cunnin’ like the woven trellis.

Fava Beans

For much of the world favas are a dry bean, particularly the “minor” race, which are small and off-round, looking much like a peanut. The “majors” are large and flattened, swollen at the hilum (eye) end. Those, too, are often used as dried beans, though in many countries, especially Europe, they are used mainly as a green shell bean, like table peas or green limas.

Favas are extremely cold-hardy; they can be sown at least as early as peas and will usually be ready to eat as early. Or earlier; we rarely have peas on the table before July 4, whereas we have eaten favas in June. Moreover, extremely early sowing doesn’t reduce later yields. Regardless of when they are sown, they seem to know when they’re good to go.

Although favas have modest nitrogen needs, they respond well to high tilth in the form of abundant humus. Since I companion them with other vegetables (usually early lettuce or multiplier onions), which are always grown with compost, the favas get plenty of humus anyway. I have had fava plants grow to be 5 feet (1.5 m) tall, and so they can work well as the centre row of a bed with shorter veggies on either side. My problem with that is that I consume proportionately more favas than that arrangement allows for; moreover, favas seem to prefer being in blocks, so I usually plant three rows per bed (rows #1, #3, and #5) and plant companion veggie crops in rows #2 and #4. Fava plants cast a dense shade, and most companions would be suppressed; but early lettuce transplants work especially well, as they are harvested before the favas get too tall. Egyptian onions are another crop that meshes admirably with favas. These are the type of bunching onions that propagate from tiny bulbils, which form where flowers should be. I get a head start by sowing the Egyptian onions late the previous fall. They just barely get established before winter, but in very early spring they make rapid growth and are ready to harvest in early June, before the fava plants can dominate them.

Fava bean stalks are relatively weak and succulent for their height, especially the large vegetable types, so I usually set up some sticks with string for support. I insert a stick every 10 feet (3.0 m) and run a single length of binder twine down each side of the row. The string is a slight nuisance and I suspect a short length of branched brush stuck in every 2 or 3 feet (0.6–0.9 m) might work as well or better; I’ll have to try that.

The tall plants begin flowering from the bottom and continue to yield successive pickings until they begin to lose vigour. You can delay that senescence by topdressing with compost when the plants are half grown or after the bunching onions have been removed (careful, though; the fava plants break over easily). Much of the benefit is from the cool moisture provided by the mulch, as well as the nutrients released with every rain (or watering, if rain is deficient—steady moisture is essential for optimal and continual bean production). Lacking that, they will tend to discontinue pod formation and concentrate on ripening what they already have, which is fine for dry fava production but not for vegetable favas. Therefore topdressing is a perfect situation to use rough, coarse compost from a batch that wasn’t quite ready for spring application. It is biologically stable but still not fully broken down; perfect.

Here is a feature of favas that seems to be little recognized and even less utilized: If you remove the older stalks as soon as they begin to senesce—signs of this are bronzing or spotting of the foliage—a second flush of stalks will sprout up from its base, usually from the crown itself, but often from the lower buds of the smaller stalks. By cutting back to these you can force a small crop of late beans (actually I don’t know why we call it forcing, as it’s quite in keeping with their own desires). The topdressing you did earlier will greatly encourage this. The second crop will be much smaller than the main crop, but here’s the tickler: Late-sown favas never do well. Later sowings are likely to fail because they are vulnerable to heat stress, aborted blossoms, aphids, chocolate spot, and more. For some reason, however, the second flush, sprouting from established roots, is much less fazed by the stress factors and will produce a modest crop of fresh green favas in a season when you could otherwise expect none.

I should mention that some folks consider fresh immature pods of favas to be tasty, much like green beans. I’ve tried them and they certainly are edible, but you may have my share; I’ll wait a couple of weeks more for the fat shell beans.

I must also mention that there is a very small percentage of humanity that finds fava beans quite inedible, indeed downright toxic. Those people have an inherited gene for favism, a condition that causes an incremental, cumulative, and irreversible reaction sometimes resulting in paralysis and even death. It’s curious that the gene is only found in ethnic groups of the Mediterranean basin, although those groups may be as diverse as Greeks, Jews, and Libyans. If you belong to one of those groups, that doesn’t mean that you must be susceptible to favism; the gene is rare even among them. It’s just that if you are, say, Italian, and your first taste of favas leaves you feeling sort of tingly and weird, perhaps you should lay off, at least until you consult your doctor and determine that it isn’t something else, like maybe falling in love.

Some folks are put off by the rather thick skins of green fava beans, and they insist on peeling them. Maybe it’s a delicacy thing, maybe they also peel their peas and their grapes, who knows? Shucks, I eat beets and carrots and tomatoes skin and all, love to crunch on grape seeds and such (you can keep your seedless watermelons). I love the light chewiness of fava skins. Also, how do I know that those skins aren’t loaded with some little-known trace element (like pandemonium) lacking in other foods? No, you must excuse me if I eat them whole; it’s just one of my little vices.

Edamame

Early on I learned that we could grow soybeans in Maine: you know, to make our own soy milk, tempeh, burgers, and so on. It occurred to me that maybe you could eat them at the immature stage. We shelled out a small batch by hand, like table peas—no small chore that—and gracious, weren’t they tasty! What a marvellous discovery I had made! Only later did I learn that the Japanese (and other Asians) had been doing that for centuries, serving them boiled in the pod and letting the eater shell them between clenched teeth. Furthermore, we learned that there are soybean varieties bred specially for that purpose: larger, more tender, and holding longer in the green shell condition. They’re called edamame, and any self-respecting natural foods eater knows all about them; even I do now.

I mostly grow Shirofumi, though this year I tried Midori and liked it very well. Edamame are sort of like kisses that way: Some are better than others, but none of them is bad. I never waste precious garden space growing just soybeans, not when I can grow them in my corn with a net gain in the yield. The soy yields somewhat less than if planted by itself, but since the corn is in no way impaired, it is a win–win game.

I will just point out here that I grow dry yellow soybeans in my field corn and popcorn, and edamame in my sweet corn. The wherefore of this is that I am in the sweet corn every day or so to pick fresh ears, and likewise the edamame, often at the same time; no point in tramping around in one crop when the other crop would just as soon I stayed out.

The main reason I am often picking them at the same time, aside from their parallel maturity, is that I often eat them together. I shell out the edamame by steaming the whole pods for a few (10 to 20) minutes before cooling them and squeezing the beans out between fingers—it only seems tedious until you have tasted them; thereafter you will do it with the bated breath of anticipation. Meanwhile I steam the corn-on-the-cob, cool it, and chop off the corn. Then I dice up one or two ripe-red bell peppers and cook them all together. We call it Chinese Succotash; after eating this stuff sex will seem boring.

Like peas, shelled-out edamame stores very well in the freezer; also like peas, they can be dehydrated. Although dried, when rehydrated they will still be an entirely different food from ripe yellow field soybeans.

Runner Beans

I always liked green lima beans as a kid, and I still would if I could grow them, but the season here is just too short and too cool. Fortunately there is a bean that tastes exactly like limas (maybe even better) but matures much earlier and loves cool weather: the runner bean. Most gardeners know about scarlet runner beans, though usually as an ornamental and to attract lots of cool moths and hummingbirds. Some folks, especially the British, like to eat scarlet runner beans as well, either as green beans or as shelled beans. Those are okay, say I; that is, I wouldn’t sniff at them if I had nothing better, but you see, I do. There is a white-seeded variation on the purple-seeded scarlet runners, which to me is in every way superior. The purple seed coat pigment that the white runners lack imparts a peculiar flavour I disprefer.

The flowers, and thus the pods, of both types form in clusters on long racemes; even the white flowers are attractive. You see, common beans (Phaseolus vulgarus) and true lima beans are largely self-pollinating, and so they feel no urge to stick their sex parts out where just anyone can see them. Runner beans, on the other hand, are promiscuous crossers; they strut their stuff for any passing luna moth, bumblebee, or rubythroat—it’s all the same to them. Not that they can’t do it to themselves—that’s what sets them apart from the obligate outcrossers like carrots—but they do seem to prefer mixing it up, which also explains the general dominance of the bright-red, attention-getting flowers, an advertisement for pollinators.

Runner beans of any colour are distinct from other beans in that they come up headfirst, whereas the others stick their neck out first and then pull the head up after. Runner beans are also distinguished by the size of their seeds, as big as any lima but twice as fat. Because of that plumpness they are not very tedious to use; very few minutes are needed to pick and shell out enough beans for a kettleful. They cook up very quickly, too.

Scarlet runners are hard to mistake for anything else, but it’s easy to see how some gardeners might take the white runners for limas, even though the runner beans are much fatter. That confusion is reflected in the names of many white-seeded heirlooms, like Small’s Carolina Lima, Whatcom Lima, Oregon Lima, Polish Lima, Christmas Lima—all runner beans.

White runner beans are truly the northern gardener’s lima bean. That may seem strange considering that runner beans originated in Central America. However, whereas common beans evolved in the Mexican lowlands, runners are from the tropical highlands or cloud forests of Guatemala, whose winter is comparable to our summer. Indeed the main place where scarlet runner beans have caught on outside their tropical homeland is England. There they are appreciated as green beans (as opposed to what we call green beans and they call haricots). In their defence runner bean pods are larger, meatier, and heartier-flavoured than common green beans.

The English are all about pedigree breeding, whether it’s people, livestock, flowers, or vegetables, and when you see the runner bean varieties they’ve produced, it is obvious they have given this species some serious attention. There are rulerlike pods and beans as big as your thumb, bred to perform in a land of peat fires and spirit-quenching fog. A “best of show” runner bean breeder flaunts his blue ribbon like the crown jewels and for better reason.

If I’m growing white runners as a dry bean, I’ll often grow them on sunflowers, but if I’m using them as a vegetable—that is, in the green shell stage—then I want easier access for frequent pickings, and so I usually plant them on poles down the middle of a bed, with shorter crops on either side. Not bulb onions, which mind the shade, nor beets, which don’t get along well with runner beans, but I suspect many others would work very well. I currently like early (Jersey Wakefield) cabbage with multiplier onions.

Although I can ripen runner beans even where I live, I can get an earlier crop of green shell runner beans if I start them in peat pots two or three weeks early and tear out the pot’s bottom when I set them out. Of course with a freezer there’s less of a rush, since I can still enjoy last year’s crop; however freezing hasn’t always been an option for me, nor do I assume it always will be.

My Chinese Succotash is none the worse if green shell runner beans are substituted for the soy, in which case onions, celery, and tomatoes are a welcome addition.

Green Beans and Green Shell Beans

Green beans with their barely formed seeds are strictly vegetables, like snow peas. It’s nice that their nodule-laden roots produce nitrate for the soil, but unlike dried beans, that doesn’t carry over to protein on our plates. So what? We appreciate them for various other things they contribute, more “minor” nutrients perhaps, but important nonetheless.

When I was a kid we always called them string beans or snap beans, and many folks still use those terms, though they no longer apply. Older green bean varieties had a tough string running down the dorsal seam; you removed that by “snapping” off the end and pulling away the “string,” thus justifying both names. Today’s varieties lack that string (unless they’re overgrown and tough) and you can either snap or cut them into shorter pieces for cooking; it’s all the same.

My hands-down favourite green bean is Jeminez, a three-purpose pole bean with robust flavour and tender quality well after the pods are overgrown. I’m not sure I would even bother to grow another green bean, except that Jeminez is a bit late to come into production; some bush beans are two weeks earlier. To get an earlier crop I always plant a row or two of a bush green bean variety, but once the Jeminez come into bearing, the bush beans are likely to be ignored. Ignored but not wasted, if I choose the right bush bean variety. Most green beans make rather poor shelled beans and worse dried beans, but some varieties are fine for both or all three uses. I avoid varieties with long slender seeds because they are harder to shell, and especially black seeds, which have a coarser flavour. My current favourite is Green Crop, a green bean with plump dull-white seeds, somewhat like a cannellini bean. Then I don’t need to worry much if I plant too many green beans, as the gone-bys (dare I say “has-beans?”) are always welcome for soup or even baking.

I mulch nearly every crop I grow, but especially green beans. My friend Betty McConnachie has discovered that she can work in her mulched beans at any time without incurring rust, and my own experience seems to confirm that. I generally avoid working around most crops when they’re wet to avoid diseases, but green beans need to be picked when they are ready and sometimes the weather doesn’t cooperate. Betty’s theory is that the rust is in the soil and rain splashes spores onto the plants from the soil, and mulch prevents that.

My late neighbour Lucian and his father used to plant an acre or two of green beans for the cannery, leaving his mother to pick them all. Even though every year they insisted that they would help, they would instead go off to haying and she would be stuck with the work. One year she made a point of going out early in the morning when the plants were all dew-laden—a big no-no—and thrashing about with her skirts as she picked. The whole crop was rusty, and the men decided that if they weren’t serious about helping, they’d best quit planting green beans. If Betty’s reasoning is correct, the beans would still have been rust-free if only they had been mulched—quite a job for one or two acres.

One type of common bean (Phaseolus vulgaris), called horticultural beans, are specifically used for green shell, horti referring to the garden as opposed to the field crop or dry beans. The word cranberry is also applied to some types of these, particularly in New England, though it only adds to the confusion, as most horticultural beans look nothing like cranberries (the one that does is superb). Typical horticultural types have maroon streaks on a buff ground, and sometimes the streaks dominate. In fact, any bean, including overmature green beans and immature dry beans (like kidneys or pintos), can be used as green shell beans, though they are not all ideal for that purpose. The best horticulture varieties are those with big fat seeds that cook quickly to a creamy texture; they often have a higher proportion of soft starch to protein and thus are less dense. For that reason Tongue of Fire is a marvellous horticultural variety but indifferent for baking.

It doesn’t matter that most horticultural beans are frost-susceptible until dry-ripe. I intend to sow all of my beans, especially pole beans, as soon as possible after Memorial Day, to be assured they’ll mature in time. However if they are horticultural beans then I can risk much later plantings: mid-June in the case of most pole beans and bush beans as late as the Fourth of July. I can do the same with dry bean varieties that can be picked for use as shell beans if necessary. Occasionally I’ve pushed planting dates too late in the season and had a crop get caught by an early frost with lots of beans still in the green shell stage. Once heavily frosted those beans will not mature—in fact they will soon begin to turn brown—but if I pick and shell them out immediately, I can package and freeze them (unblanched) for an easy supply of quick-cooking beans.

If I have a surfeit of shell beans and a dearth of freezer space, I often just spread out the shelled beans on screen racks to dry. Depending on how ripe they are they end up looking much like dry beans, only wrinkled, and they can be stored and cooked up like mature dry beans, only they’ll cook up quicker and creamier. This only works if they are mature enough to have full colour; if the beans are still green they may turn brown on the drying racks, though they are still fine for the freezer. Of course none of these is usable for seed for future planting.


Reprinted with permission from Will Bonsall's Essential Guide to Radical, Self-Reliant Gardening by Will Bonsall and published by Chelsea Green Publishing, 2015.