How to grow American groundnuts in your garden

Last Updated on November 8, 2022 by Aaron von Frank

Find out how to grow American groundnuts and use them in your kitchen. This medicinal native root crop was beloved by Native Americans and helped save early European colonists from starvation.

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No, American groundnuts (Apios americana) are not the same thing as peanuts (Arachis hypogaea), which are also commonly called groundnuts. Both species are in the legume/bean family and are able to produce their own nitrogen fertilizer via the process of nitrogen fixation due to their relationship with symbiotic soil bacteria.

However, the similarities between the two plants pretty well end there.

Peanuts (originally from South America) are prized for their oil-rich, high protein underground pods/seeds. American groundnuts (from North America) produce starchy, protein-rich tubers that were a prized staple crop for pretty much every Native American culture throughout the eastern United States and Canada where the plants are endemic. 

Were it not for being introduced to American groundnuts by the native Wampanoag people, the Pilgrims likely would have starved to death during the first couple of years in the New World. If you want to include something on your Thanksgiving table that may have actually been eaten at the original harvest meal in 1621, include some cooked groundnuts.  

Despite their rich history and native plant status, American groundnuts have thus far failed to gain widespread adoption in modern US agricultural systems. Meanwhile, peanuts are now grown the world over and are a staple food. 

Why? The main reason: time. 

Peanuts produce a crop in a single growing season. American groundnuts require at least two years to produce a good yield.

Peanuts are also short, mounding plants that don’t exceed 2′ in height — very easy to cultivate. American groundnuts are large vining plants that will easily exceed 10′ in height in mild climates with long growing seasons — a more resource-intensive growth habit. 

These “shortcomings” don’t mean American groundnuts can’t — or shouldn’t — be an important crop in the United States, especially for home gardeners. The case for American groundnuts as a vitally important crop is made even more apparent given their potential as a medicinal plant. (More on that below.)  

American groundnuts by any other name 

To alleviate any confusion, we should also mention that American groundnuts have quite a few other common names, which is often the case with plants with widespread geographic distribution. A few other names you may have heard: 

• cinnamon vine, 
• Indian potato, 
• potato bean, and 
• hopniss. 

The confusion caused by the name “groundnut” is why some advocate giving American groundnuts their own dissimilar common name based on one of their Native American names: hopniss. 

In 1749 when traveling through the British colonies that would soon become the United States of America, Swedish botanist Peter Kalm wrote:

“Hopniss or Hapniss was the Indian name of a wild plant, which they ate at that time… The roots resemble potatoes, and were boiled by the Indians who ate them instead of bread.”

There again, each Native American culture had its own unique name for the plant, so hopniss was by no means universal then or now. But it is a pleasing name shared by no other plant, so why not? 

American groundnuts: other edible parts 

While the large underground tubers are the edible gold of the plant, American groundnuts also produce edible beans (which need to be cooked prior to eating) plus edible growth shoots and flowers (which can be eaten raw). 

The beans on our cultivated variety look pretty similar to the beans of any standard vining snap bean. However, the plant takes far longer to develop beans than typical garden bean plants.

Our American groundnut didn’t start producing flowers and bean pods until August. We didn’t eat the beans pods since we wanted to use them as dried beans.

When popping open the mature pods after first frost, we were disappointed to see virtually no bean seeds inside the pods. While most legumes are self-fertile and don’t require another pollenizer nearby, apparently American groundnuts (or at least our cultivar) will set more seeds with a genetic mate nearby.  

2022 update: Our American groundnut plants produced MUCH more prolifically in the dry bean category in summer 2021 due to us doing a better job of watering the plants. It’s likely the low production of summer 2020 was due to plant stress due to lack of water.

The edible flowers of American groundnuts are gorgeous and quite fragrant, oft described as a combination of lilies and cinnamon (a reason for another common name, “cinnamon vine”). 

The flowers are pleasant tasting (mildly bean-like and similar to kudzu flowers) and can be eaten raw. They make a very attractive garnish. 

The plant’s growth shoots and young leaves can also be eaten, but doing so will inhibit the plant’s ability to pump energy into its rhizomes/tubers. These edible green parts are also unremarkable, so we don’t really see the upside to consuming them. If they were as tasty as Austrian winter pea shoots, we’d reconsider.  

How to grow American groundnuts in your garden 

After experimenting with these plants for a couple years, here are our recommendations for home gardeners interested in growing American groundnuts: 

1. Get improved varieties. 

Yes, you can forage for American groundnuts in the wild and find patches that will produce large yields. Yes, you can plant some of your wild-foraged tubers or even the beans in your garden to get your own colony started. 

However, the tubers produced from the wild plants are not likely to yield nearly as much or as quickly as the “improved” varieties courtesy of modern breeding work (primarily done a few decades ago at Louisiana State University). If you buy groundnut starts/tubers online, aim for improved varieties, not wild types.

We got our original American groundnut tubers from Oikos Tree Crops. (We’re growing ‘Nutty #3’, which came out of the Louisiana State breeding program.) There are other online sellers as well. 

2. Start from tubers rather than seed.

To get a faster harvest, start your American groundnuts from 1-2 year old tubers rather than from seed. Plant your groundnut tubers 3-4″ deep in soil amended with compost as soon as you’re past your last frost date.  

When it comes time to harvest your new tubers in 1-2 years, save the smaller ones for future plantings and use your larger tubers for food. To store your planting/seed tubers, put them in potting soil in ziplock bag stored in your fridge. You’ll want the soil to be almost dry, not damp, or you risk rotting them. 

2. Use a large trellis. 

As mentioned, American groundnuts are LARGE vining plants. In warm climates with long growing seasons, second year plants can grow as tall as 20′ in a growing season. First year growth doesn’t tend to exceed about 10′.  

Our second year plant reached about 15′ in height using a gutter downspout (and itself) as a trellis. If you don’t have a large trellis, the plants would also grow well spread across a tall chainlink fence, an arbor, or climbing up the edge of a tree.

Without a trellis, expect a large sprawling mass of vegetation. They’ll still grow and produce tubers, but your chances of winning your neighborhood’s yard of the year award will be diminished.  

3. Grow in a large grow bag. 

The edible tubers of American groundnuts grow like beads on a string along the plant’s roots. These roots can run quite a long distance away from the plant as it matures over 2+ years, making harvest difficult. 

If you’re into no-till organic gardening like we are, you might also notice that tunneling voles thrive in your garden, making certain crops more difficult to grow. (Read: crops with roots that voles find tasty.) 

So, to:

• make harvesting easier,
• prevent the plant from running/growing in unwanted spots, and
• eliminate the potential for crop loss to voles,

we recommend growing American groundnuts in large grow bags. We grew our plant in a 24″ wide x 16″ deep grow bag.  

4. Create ideal growing conditions. 

In the wild, American groundnuts tend to be “edge” plants, growing in clearings and openings along creeks and riverbanks. Thus, they can tolerate a fairly wide range of growing conditions from part shade to full sun; damp soil to relatively dry soil. 

In the hot, sunny south with long growing season, part-shade will work fine. In the north, you’re probably better off selecting a full sun-location. 

You’re also going to maximize tuber size by:

• amending the planting spot with compost prior to planting;
• top-dressing the soil with 3″ of mulch; 
• maintaining slightly damp soil throughout the growing season.  

What’s the yield per plant of American groundnuts? 

Under ideal growing conditions using improved varieties of American groundnuts, you can get up to 7 pounds of tubers per plant at the end of your second growing season. 

We got about 3.5 lbs of tubers from our grow bag plant. This lower yield was likely due to parental neglect throughout the summer since we had an actual human baby who received more tending than our plants. Had we watered them during the hot, dry periods and kept a thicker layer of mulch over them, we’d like have achieved a better yield. 

How big are American groundnuts? 

The size of harvestable American groundnut tubers will typically vary between 2-10 ounces, from about the size of a golfball to the size of a baseball. The older the bigger. (“Harvestable” because there will be smaller tubers on the bead-like roots that should be used to grow future plants rather than for food.)

Our original tuber (which we assume to be 3-4 years old at harvest) weighed in at just over 8.1 ounces at the end of this year’s growing season. The majority of the plant’s tubers were in the 2 ounce range, about the size of a golfball.  

The largest American groundnut tuber we’ve grown to date was 1 lb 2 ounces (grown in the summer of 2021).

Are American groundnuts susceptible to pests?

We never gave them the opportunity, but we suspect voles would find American groundnut tubers delicious and make quick work of them. Rather than test that hypothesis, we used a grow bag.   

Thus far, the only American groundnut “pests” we’ve noted are the larvae of long-tail skipper butterflies (Urbanus proteus), which roll up in the leaves while munching. The caterpillars don’t tend to do significant damage to the plants and we adore the mature insects.  

 

 

 

 

 

 

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American groundnuts are also the host plant for the silver-spotted skipper. So keep an eye on the leaves of your native American groundnuts and you might also get to enjoy seeing native pollinators going through the early phases of their lifecycle.   

Do American groundnuts have medicinal properties?

American groundnuts are nutritional powerhouses, providing “an excellent source of protein containing three times the crude protein content of the Irish potato (16.5% of dry weight). Seeds may have as much as 25-30% crude protein.” (source)  

In addition to their nutritional benefits, both the flowers and tubers of American groundnuts contain compounds with medicinal properties in line with their historical use by Native American societies. For instance: 

• American groundnuts “contain high levels of the isoflavone genestein. Evidence suggests that the dietary isoflavones found in apios [American groundnuts] are of significant amounts and may prevent breast and prostate cancer.” (source) 
• AFP-2 polysaccharides found in the flowers have potent neuroprotective properties, e.g. they’re good for brain health. (source)
• Compounds in the tubers have anti-inflammatory effects. (source) 
• Polysaccharide compounds in the flowers improve immune response in immunosuppressed mice (and perhaps in people, too). (source) 

There’s probably quite a bit more research out there showing the medicinal and health benefits of American groundnuts. In summary, you can grow a delicious high-protein native food that also has some pretty interesting health potential.

As one study summarized: “The discovery of genistein in A. americana tubers should rekindle interest in this legume as a food crop since genistein has been shown to reduce the incidence of various forms of cancer.” 

How do you eat American groundnuts? 

Before jumping into how to use American groundnuts in your kitchen, an important health warning: some people experience severe gastrointestinal distress after consuming American groundnut tubers. 

To avoid such discomfort, two tips: 

1. Boil or bake your American groundnut tubers prior to using them in a recipe.

You should boil your American groundnuts for AT LEAST 30 minutes (for small tubers) before using them in a recipe. Larger tubers should be boiled for closer to an hour. 

For instance, if you want to saute slices of groundnut tubers in a pan, boil them for 30 minutes first, then slice and saute them.

To be crystal clear: you should never eat groundnut tubers raw unless you want to spend time on-site contemplating the decorating decisions of your bathroom. That’s because American groundnut tubers are very high in lectin. Cooking/boiling degrades lectin, thus rendering it inert.   

Exceptions to this “cook before cooking” rule with American groundnuts are recipes like our American groundnut and maitake mushroom chowder, wherein the tubers are diced small and cooked for a long time. 

2. Only eat a small amount of American groundnuts your first time.

Instead of eating a large meal of groundnuts your first time out, only eat a couple bites then wait to see how your body reacts before eating a larger quantity next time.  

For the record, The Tyrant and I have eaten both small and large quantities of American groundnuts in a single sitting and have not experienced the slightest reaction to them. They were well-cooked first.

What do American groundnuts taste like?

To us, American groundnuts taste like a cross between a white potato and a peanut. Their consistency is slightly starchier than potatoes; more bean-like or as The Tyrant noted, “the consistency reminds me of jackfruit seeds.” 

Being a southerner, I’m well-acquainted with the smell of boiled peanuts. The smell of boiling American groundnuts is almost identical to the smell of boiled peanuts.

We’ve only eaten one type of American groundnut so can’t speak to potential variability between varieties or growing conditions/regions.  

How to use American groundnuts in your kitchen:

There are as many ways to use American groundnuts as there are ways to use potatoes. (Related: you’ll also want to store your groundnut tubers the same way you store potatoes: in a cool, dark, dry place – aka your pantry.) 

Here are a few ideas:

• Mashed groundnuts – like mashed potatoes, but better; 
• Groundnut winter squash soup (two native foods that were surely paired by Native Americans); 
• Boiled, dried, and powdered into flour to be used as a soup/stew thickener or in other savory recipes;  
• Fried or sauteed thin-sliced groundnut chips. 

Groundnuts are not a strong flavor that will steal the show any more than potatoes are, so plan accordingly.  

Do you have to peel American groundnuts prior to eating? 

No, you don’t have to peel American groundnut tubers before eating them. In some varieties, the older and larger the tubers get, the thicker and more fibrous the outer skin will be, so it’s best to remove it. In our ‘Nutty #3’ groundnuts, the skin on the largest tuber was no thicker than the smaller ones.   

When boiling groundnuts, leave the skin on to best preserve the flavor and nutrition, then peel after boiling if needed or desired. 

Recipe: Pan-fried American groundnuts

Want to try a small amount of groundnuts for the first time to gauge your reaction? Need a simple recipe that will help you get a true taste of the tubers? 

Try our simple pan-fried groundnut recipe:  

We hope you’ll consider growing American groundnuts in your garden! We’d like to see this history-rich, medicinal native plant enjoy a resurgence, which can start with you. 

KIGI,

Other helpful articles you’ll love: 

• Recipe: American groundnut mash with rosemary brown butter
• Recipe: American groundnut and maitake mushroom chowder
• How to propagate and grow Peruvian ground apple, aka yacon
• How to grow organic turmeric and ginger in any climate zone
• Root pouch: a helpful tool for patio & container gardening