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.)

Slices of pre-boiled American groundnuts sizzling in a cast iron pan in our kitchen.

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.

American groundnut bean pods.

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.

Very few beans set in our American groundnut bean pods, perhaps due to the lack of a pollenizer.

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.

American groundnut flowers look like clusters of little orchids.

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.

This was an average-sized American groundnut tuber from our second year plants. We grow ‘Nutty #3’, an improved strain from LSU’s breeding programs in the 1980s and 90s.

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 American groundnut vine in late July.

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.

Groundnut rhizome with enlarged tubers that develop like beads on a string.

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.

Groundnut tubers develop just below the soil surface as you can see here.

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.

A large American groundnut that weighed just over 8 ounces.

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.

Possible vole defense? The roots of American groundnuts emit a sticky latex/rubber when cut. This latex goes away after they’ve been out of the ground for a week or so. Perhaps this defense would deter voles from eating them – we didn’t want to risk it. If groundnut latex sticks to your hands or knife, simply use a bit of vegetable oil to help rub it off.

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.