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My earliest memory of nettles involves blissfully running through an open forest, only to be assaulted by an itchy, stinging sensation all over my bare legs. My Papa informed me it was "Brennnessel," the German word for stinging nettle, which translates literally as "burning nettle." In fact, its name all across Europe alludes to this irritating quality. It has provoked the ire of gardeners, hunters, and outdoor enthusiasts across the world. However, for centuries (at least) it has also captured the love of herbalists and foragers, due to its medicinal properties, strengthening nutrients, and delicious taste. 

Distribution and Identification

Stinging nettle (Urtica dioica) is widespread across North America; Arkansas is the only state where it is not reported. Three distinct subspecies are found within this distribution: dioica, which is native to Europe; holosericea, native to the western US; and gracilis, native to most of North America.

Stinging nettle is distinguished by its square stem and opposite leaves. The mint and vervain families are the only other herbs with this characteristic, and their flowers look very different. Whereas mints and vervains typically have colorful irregular flowers, those of nettle are creamy, greenish, or pinkish, and grow in drooping or spreading clusters from the leaf axils. The individual flowers are tiny and hard to distinguish. They typically bloom from June to August. I don't have any good pictures of them, but here are some close-ups.

Nettle leaves are egg-shaped to lance-shaped, 3 to 6 inches long and 1/2 to 1 1/2 inches wide. They are coarsely toothed and the underside is slightly hairy, or has a few stinging hairs. If the leaf "bites" you, you definitely have the right plant! The stem usually contains more stinging hairs, so that's a better place to look for them.

The plants themselves can get quite large, occasionally reaching heights of up to 6 feet. One to 3 feet is more common.

In addition to stinging nettle, wood nettle (Laportea canadensis) occurs in eastern and central North America, from Florida to Quebec and Saskatchewan to  Louisiana. It differs from stinging nettle in that it prefers wooded habitats, is generally more heavily armed, and has alternate leaves that are more oval-shaped. It is also a choice edible; in fact, many people prefer it to stinging nettle. 

False nettle (Boehmeria cylindrica) can be confused with stinging nettle, but it is hairless, has unbranched flower clusters, and typically has a shiny, light green, nearly translucent color, in contrast to stinging nettle's matte, rich green. The clearweeds (Pilea pumila and Pilea fontana) look similar to false nettle, but they are usually smaller plants, and have branching flower clusters. Neither plant is considered edible nor poisonous to humans.

How to Harvest Stinging Nettle

Stinging nettle isn't terribly picky about where it grows; and once you find it, you're likely to find an entire colony. Check moist fields, riversides, creeksides, and shorelines. It also grows in open woods and thickets, in full sunlight or light shade.

The ideal time to pick stinging nettle is in mid-spring, early to late May in the Twin Cities area. You can pick it later than that, but it becomes tougher as it grows. Also, there is some debate about whether it is safe to pick after flowering. As the leaves mature, they develop cystoliths, which are basically inorganic compounds (usually calcium carbonate) stored in specialized cells. These may irritate the liver and kidneys, but there's definitely not consensus on this topic. Regardless, if you want to stay on the safe side, you can dry any nettle picked after flowering and use it for tea. Drying destroys cystoliths.

[Edit: After further research on the topic, it appears that drying does not destroy cystoliths. Some articles on nettle make this claim, but I now believe this comes from a confusion between cystoliths and the stinging hairs, which are called trichomes. Trichomes are also known as cystolithic hairs; however, they are separate and distinct from cystoliths. Drying does destroy the stinging hairs (cystolithic hairs), but apparently not the cystoliths. See, as evidence, this article about nettles, which states that “Cystoliths are… usually visible only in dried material;” also see this study of plant cystoliths, which subjected them to high temperatures of up to 400 degrees Celsius (752 degrees Fahrenheit), and they remained intact, though brittle and with a somewhat altered chemistry. Of course heating something to 400 degrees Celsius is far beyond any temperature reached in drying or cooking.

Though cystoliths appear persistent, this isn’t necessarily a bad thing. I couldn’t find any evidence that they actually present a danger to humans. Plant cystoliths are mostly composed of amorphous calcium carbonate and also contain some silica (source). Calcium carbonate is basically chalk and is added to supplements and medicines—it’s the active ingredient in Tums, for example. There is evidence that amorphous calcium carbonate is the most bioavailable—meaning that it’s most easily digested by our bodies. However, it’s also the most unstable form of calcium carbonate—once isolated, it needs the support of additional elements, or it will crystalize into a more stable form of calcium carbonate within seconds. However, as mentioned above, plant cystoliths are very stable, so it is reasonable to believe that they represent a highly bioavailable form of calcium. Indeed, at least one study shows that nettles harvested in September have the highest amounts of calcium, magnesium, and boron of any samples collected throughout the year. So why is this presented as a danger?

Well, part of it might just be due to the proclivity of people in post-industrial societies to demonize things from the wild. I frequently notice that perfectly edible and healthy wild plants are labeled as “toxic” in botanical literature. However, I also think it comes from warnings associated with calcium carbonate; it is contraindicated for people with kidney stones, and can cause digestive upset. If this concerns you, I would suggest not eating nettle after it flowers. I personally find it too tough to eat at that point anyways, but I have made tea with it and didn’t experience any negative side effects. Regardless, I don’t think it should pose a health concern for most people.]

Stinging nettles are best harvested with gloves. I have harvested them without gloves in a pinch and emerged pretty much unscathed. However, the subspecies of nettle native to Minnesota, Urtica dioica gracilis, has fewer stinging hairs. You may not want to try it with your variety of nettle, and I definitely wouldn't recommend it with wood nettle!

When harvesting, simply break off the top few inches, stem and all. As the growing part of the plant, this is the most tender portion. The stem should break easily. If it doesn't, it's too tough to eat, but can still be dried out and used for tea.

Nutritional and Medicinal Properties

This wonderfully versatile plant is used to treat a host of illnesses. As a diuretic, it can soothe urinary tract infections. It is widely used to treat Benign Prostatic Hyperplasia (BPH), an enlarged prostrate gland. Especially when used in combination with saw palmetto, it is effective at relieving the urinary symptoms of BPH. It may also slow the growth of certain prostrate cells. 

Stinging nettle is often used to treat allergies. It helps reduce the sneezing and itching associated with hay fever. It is believed that nettle lowers the amount of histamine produced by the body, thus decreasing the allergic response. 

For those with menstrual problems, stinging nettle is a very useful herb to keep on hand. Due to its diuretic properties, it can help ease bloating caused by PMS. It can also stem heavy periods. Furthermore, nettles can be used as a tonic during pregnancy, and to increase milkflow after giving birth. It is also used as a restorative remedy during menopause.

As a remarkably nutritious "superfood," nettles have a long history of treating anemia and convalescence. They contain a myriad of vitamins and minerals, particularly vitamin A, vitamin K, iron, potassium, and calcium.

In the treatment of the above conditions, nettle is typically taken internally as a tea or tincture. However, the actual nettle sting is medicinal as well! The stinging hairs of the nettle are like tiny hypodermic nettles, which break off when you touch them and release irritating chemicals into your skin. The itching, burning sensation is instantaneous, and a rash may develop. One of the culprits is formic acid- the same chemical found in bee stings. And like bee stings, nettle stings can relieve arthritis and rheumatism. But it is certainly not a treatment for the faint of heart!

How to Eat Stinging Nettle

Stinging nettle is a delicious plant whose taste is often compared to spinach. Personally, I think it has a stronger "green" flavor than spinach; but I don't think this is a bad thing. If you like veggies like kale, collards, and broccoli, you'll definitely like nettles!

Drying, freezing, and cooking destroys the stinging quality of nettles. When drying, be sure they get plenty of air flow. Low humidity is ideal, but not always possible in certain climates. Heat and sunlight aid in the drying process, but they're actually detrimental to the finished product, as they destroy the more delicate compounds and flavors. Avoid applying heat or sunlight if possible.

If freezing for a long period of time, blanch them first. If they're only going to be in the freezer for a couple weeks, it's fine to put them in a bag and stick them right in. This is usually what I do, as I add nettles and other greens to smoothies quite frequently.

Nettles are delicious steamed or sautéed, and served with lemon juice and butter or olive oil. They can generally replace spinach in recipes. If you're feeling ambitious, you can put them in spanakopita, a Greek pastry traditionally made with spinach, feta cheese, and scallions. Or try them in biscuits, scones, or savory waffles!

Nettle Asiago Scones

You can't really go wrong with herb and cheese pastries, and these scones are no exception. Served with a side of yogurt and a cup of tea, they make the perfect breakfast! 

Ingredients

• 2 1/2 cups unbleached all-purpose flour

• 1 tablespoon cane sugar

• 2 1/2 teaspoons baking powder

• 1/2 cup (1 stick) salted butter, chilled and chopped into cubes

• 3/4 cup kefir

• 1/2 cup packed frozen nettle, finely chopped

• 2 tablespoons chives, chopped

• 1/2 cup grated asiago cheese

Directions

1. Preheat oven to 400°F.

2. Whisk flour, sugar, and baking powder together in a large bowl.

3. Add butter to flour mixture. Use a pastry cutter, fingertips, or two knives to process until the mixture resembles a coarse meal.

4. Add chives, nettles, and cheese. Mix until evenly distributed. Add kefir and mix gently with your hands until just incorporated. Lightly knead until it holds its shape. You don't want to overwork the dough, or the gluten will develop and it will become bread-like.

5. If the mixture is too dry, let it sit a couple minutes, so the flour can absorb the liquid. If it still doesn't hold its shape, add 1-2 more tablespoons kefir. The dough should be dryish, but still hold together.

6. Turn dough onto a lightly floured surface and gently press into an 8" diameter circle. It should be about 1" thick.

7. Cut dough into 8 even triangles (like how you would cut a pizza.)

8. Place scones on greased baking sheet. Bake 25 minutes or until golden brown. Immediately move them to a wire rack to cool.

**Ingredient notes:

• I used kefir in the recipe because I think it's tasty and it was on sale at the co-op. You could substitute buttermilk or yogurt, or just use plain milk for something less zesty.

• Instead of chives, try using ramp greens, garlic mustard stems, or any of the other wild Allium species!

• Any hard cheese would work well in this recipe. I like asiago, but you could try it with parmesan, romano, or sharp cheddar.

A Sting By Any Other Name

Hopefully this post has shed some positive light on this much maligned plant. Next time you hear someone complain about this "obnoxious weed," whip them with the stems and let them know you just gave them a healthy dose of medicine! Just kidding.

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