edible gardening

The Three Sisters

By Jeff Cox / Photography By Natalie T. Mcgarvey | May 24, 2017
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On the reverse side of the 2009 U.S. $1 gold coin, or “Sacagawea dollar,” you’ll find a depiction of a Native American woman growing corn, beans and winter squash in an arrangement widely known as the three sisters.

This combination is one of the world’s great horticultural achievements, and a perfect expression of Native Americans’ keen insights into nature. Its roots go back more than 10,000 years, and it still works brilliantly in today’s modern gardens. Up until about 10,500 years ago, natives of the western hemisphere were hunter-gatherers, anthropologists believe. In the jungles between Guatemala and Mexico, a wild squash grew. Its fruits were bitter and scant, but the seeds were tasty, so the indigenous people began to plant and care for them. Over the next 5,000 to 6,000 years, this squash became domesticated as the natives selected strains for the qualities they liked: larger, meatier and less-bitter fruits. Seeds of the improved squashes were traded and soon tribes throughout North and Central America were growing them.

About 9,000 years ago, teosinte, a wild grass of southern Mexico, hybridized with another wild plant—scientists aren’t sure which one—creating a plant with a small seedhead with neat rows of tiny seeds. Through subsequent generations, strains with larger and more abundant seeds were selected until, about 5,000 years ago, early modern corn appeared. It was about that time that wild forms of beans were brought into the native tribes’ gardens.

Protected in human gardens, the plants underwent huge changes in composition and shape. Selecting for better taste meant that these foods were more suited to their human consumers nutritionally, as good taste is a predictor that a food is good for you. But domestication works both ways. Devoting more time to caring for the plants meant establishing villages and less time roaming the woods looking for game. Farming became a way of life.

As Amanda J. Landon wrote in the January 2008 issue of Nebraska Anthropologist, “In Central America, the three sisters and humans shared a co-evolutionary relationship in which humans invited the plants into the human niche, and the plants thrived. Both humans and the three sisters now share a symbiotic relationship, where both the plants and humans depend on one another.”

The modern forms of the three sisters couldn’t survive without us. Squash lost its unpalatable bitterness, which was its defense mechanism against insects and birds. Forms of squash that we now call summer squash, such as zucchini and Patty Pan, lost their tough skins. They need the protection against predators that human growers afford them.

Modern corn certainly couldn’t persist on its own. When we plant corn, we have to remove the kernels from the ear and space them apart so each can mature into a whole plant. Left on its own, a corn cob’s kernels are too tightly packed together to make a viable stand of corn.

Likewise, the wild progenitors of pole and lima beans still grow in many places in Central America, especially Guatemala. They too were domesticated, bred for size and flavor, and lost the ability to ward off predators by producing bitter and, in most beans, even poisonous compounds.

Poisonous compounds do still exist in some modern beans. Lima beans contain a compound that, if eaten raw or undercooked, is metabolized into hydrogen cyanide. And raw or undercooked red kidney beans also contain a poisonous compound. Ten minutes of boiling detoxifies both types of beans, but it must be a full, rolling boil and at least 10 minutes for complete detoxification. Cooking red kidney beans at anything less than a full boil for 10 minutes actually intensifies the poison. So avoid tossing a handful of uncooked beans in the slow cooker. And don’t nibble raw snap bean pods when you’re cooking them.

Scientists have tried to hybridize the wild progenitors with the modern types, but they’ve diverged so much over the millennia that all attempts to cross them have failed.

Baker Creek Heirloom Seeds has an outlet at the Petaluma Seed Bank (199 Petaluma Blvd. North) offering lots of heirloom pole beans, the type needed for a three sisters planting. You can eat tender young pods of pole beans as you would snap beans, but the varieties I’m recommending here are best for drying on the vine and shelling out for storage. All can be found at the Seed Bank or ordered through Baker Creek:

Good Mother Stallard—Maroon and white beans, creamy texture, nutty flavor.

Haricot Tarbais—This white bean is traditional in French cassoulet.

Henderson’s Black Valentine—Excellent black bean for tacos and burritos.

Hidatsa Red Indian—Heirloom of the Hidatsa tribe, climbs only to three to four feet.

Ojo de Cabra—Dark stripes give the plump beans the appearance of a goat’s eye.

Cherokee Trail of Tears—Shiny black beans commemorate the Indians’ sufferings.

That humans have grown to depend on corn, beans and squash as staple crops is undeniable. The extensive native civilizations of pre-Columbian North, Central and South America grew these three crops, and the people thrived. One of the chief benefits of eating the three foods together is that they supply all eight essential amino acids that make up a complete protein.

Corn is deficient in the amino acid lysine, but lysine is supplied by beans and other legume seeds. A corn-based diet without lysine causes a shortage of niacin, or vitamin B3, which can lead to a particularly nasty disease called pellagra. Besides growing the three sisters, Native Americans about 3,500 years ago in Guatemala and Mexico learned to cook their corn in water made alkaline by the addition of lime, wood ashes or even ground snail shells. The first benefit of this process, called nixtamalization, is that it removes from 97% to 100% of aflatoxins from fungus-contaminated corn. Aflatoxins are virulent cancer-causing compounds.

Nixtamalization also makes the corn easier to grind and improves its flavor and aroma. The alkalinity helps dissolve the cellulose in corn’s cell walls, softening it. It loosens the hulls from the kernels so they can be easily removed, and breaks down some of the corn oil into emulsifying agents while bonding some of the corn proteins with polysaccharides. The result is that while untreated cornmeal won’t form a dough when water is added, nixtamalized corn will—giving us masa, tortillas, hominy and, as the name of the process suggests, tamales.

Squash is chockablock with vitamin A, vitamin C, complex carbohydrates, fiber and amino acids. Here’s a rundown:


Just one cup of cooked winter squash contains, as a percentage of your daily requirement:

Vitamin A—59%
Vitamin C—26 %
Fiber—23 %
Vitamin B6—19%
Potassium—14 %
Vitamin B2—11%
Vitamin K—10%

Plus good stores of omega-3 fatty acid, magnesium and vitamin B3. All with just 76 calories in the cup.

All winter squashes are nutritionally power-packed, but I think the best flavor comes from Butternut or Hubbard. Many years ago, when I was living Back East, there was a field of winter squashes—red Hubbards— beside the road I took to work. One day at harvest time, I saw a big truck with “Mrs. Smith’s Pies” painted on it parked by the road and a crew was loading ‘Big Red’ Hubbards onto it. I stopped and asked the crew chief what the company did with the Hubbards. “We make pumpkin pies out of them,” he said. “Pumpkins make lousy pumpkin pie. Hubbards are much better, and to tell you the truth, Butternuts are even better.”

It was heading toward Halloween when I always make a pumpkin pie, so that year I made my pie out of a Butternut squash—and never looked back. Now I always use Butternuts. The flesh is more colorful, the texture is smoother, and the flavor is richer.

So those are the three sisters. And the Native Americans also devised a way to grow them together so that they support each other. This clever technique dictates their arrangement in the garden, and it’s something you can easily do as well.

Start with a plot of loosened and well fertilized soil. Shape it into flat-topped mounds about a foot high and 20 inches across, spaced six feet apart, in rows four feet apart. The tribes of the Northeast Atlantic coast would bury a fish or eel in each mound of their poor, sandy soil to supply extra fertility, a story we know from historic accounts of the arrival of the Pilgrims in Massachusetts.

Plant three corn kernels just inches apart in the center of each mound. When the corn is six inches high, climbing beans and the types of winter squash that send out long runners with wide leaves—in other words, not “bush” types—are planted alternately around the circumference of the mound, about three seeds each of beans and squash for a total of six for each mound.

As the corn grows, it provides a stalk for the beans to climb. When the beans start elongating their stems, guide them to the corn stalks by hand. Once they begin to twine around the corn stalk, they’ll take it from there. Some types of climbing beans are very vigorous and you may have to either weave them back down the stalk, or snip out a foot or two of the growing tips, which encourages the beans to put energy into side shoots. When the corn tassels and starts to shed its pollen down on the silks that emerge from the tip of the ears, make sure the beans aren’t interfering with the line of sight between silks and tassels. Corn really unloads tons of pollen, so just make sure the silks aren’t covered with bean foliage. When it comes time to harvest the corn, let the stalks stand so the beans can dry out still attached to the stalk. This keeps the pods up in the sunlight and air, enhances drying, and prevents mold.

Meanwhile, the squash will be covering the ground with its lush runners between the mounds. The big, wide leaves will become a living mulch, shading the soil, suppressing weeds and helping to keep the soil moist. You may need to guide the runners as they grow so you have some room to step in the rows and to keep them off the mounds of beans and corn. Just handle them gently and they won’t mind being guided. As the winter squash fruits develop, set them on a handful of straw or anything else you have that will keep them off the bare soil. This prevents molds, insects and worms from attacking the fruits. Also, the squash stems and runners are covered with bristly hairs that make life difficult for some pests.

Native tribes of the American Southwest and northern Mexico often planted a fourth sister, Cleome serrulata, the Rocky Mountain Bee Plant, which attracts pollinators. In our neck of the woods, just plant some borage. Local bees will find the borage and then go on to pollinate your squash.

Article from Edible Marin & Wine Country at http://ediblemarinandwinecountry.ediblecommunities.com/eat/three-sisters
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