Just like we might prepare an herbal tea infusion to give ourselves a boost, we can also prepare an “herbal tea” for our plants using common weeds found in the garden.
Weeds can tell us things about our soil. You may notice that dandelions tend to pop up in compacted areas or yellow nutsedge grows in the wet areas of your garden. To be fair, some weeds really don’t discriminate, but if you pay close attention, you will start to notice patterns.
Stinging nettle (Urtica diocia) is a common weed that is honestly the bane of most people’s existence. Other common names are tall nettle and slender nettle. You will know when you’ve found a patch of nettles! As soon as you touch them, you will feel a sharp sensation, like light stings splintering across your skin. Small red bumps will form across the affected area. Unfortunately, it may take several minutes in order for the stinging sensation to wear off.
Growing up, we used to call stinging nettle “itchweed”. It grew prolifically in the woods along the creek. Thinking back, this makes complete sense because nettles prefer to grow in rich soils. Forest floors and creek banks are the perfect habitat for a plant that loves rich soil, because you have decaying leaf matter from the trees and topsoil that’s been washed from the fields through surface runoff near the creek edges.
Nettles also like moist soils (again, creek and ditch edges, low-lying areas), but they can tolerate some drier soils as well.
Nettles pop up in patches because they spread mostly via underground rhizomes (roots). Identifying nettle is fairly easy:
- Dark green color growing up to 2 m tall (6.5 feet!)
- Leaves can be broadly egg-shaped, ovate, or lanceolate with sharp point at the tip
- Deeply toothed leaf margins
- Petioles are ¼ to ⅓ the length of the leaf blade
- Combination of bristly hairs and larger stinging hairs on the leaves (mostly the stinging hairs on the underside of the leaf, though there are some varieties that have stinging hairs on the upper side of the leaf too)
- 4-angled stems with stinging hairs
- Greenish-yellow flower clusters form at the leaf axils from late May to October
Again, nettles thrive in nutrient-rich soils and are not typically found in soils with low fertility. So if you have a patch of nettles in your backyard, take it as a sign that you have fertile soil!
The stinging hairs do not actually create an allergic reaction, but rather act as a mechanical skin irritant. The hairs break off when coming in contact with skin and then act as a hypodermic needle which injects histamine, acetylcholine, and 5-hydroxytryptamine into your skin. You feel localized pain and swelling that will wear off within a few minutes to a few hours.
A weed is just a plant that’s growing where you don’t want it. Most people would say that nettles are most definitely weeds, but they are also a medicinal plant, food, and source of natural cordage (similar to hemp).
Because nettles are so rich in vitamins and minerals (like calcium), it is considered a great tonic herb to fortify the body. People have used nettles to treat allergies, urinary tract infections, and liver imbalances because it is astringent and anti-inflammatory (which is interesting considering the stings!).
Disclaimer: This article is for educational purposes only. Please consult your medical practitioner before ingesting or using any herbs.
Harvesting and Collecting Stinging Nettle
When collecting nettle, it is wise to wear gloves and long sleeves. Once the leaves have wilted, it no longer “stings” you and is safe to work with barehanded.
But why would you want to collect nettles other than to make a nettle pesto, soup, or tincture?
Your plants will love nettles just as much as your body! We can make a special herbal brew to fertilize our plants, and that is just what I did when I had a patch of nettles pop up in my high tunnel last year.
I have a plastic-covered high tunnel (basically, an unheated greenhouse) where I try to extend the season for my cut flower production. In the past, I have also grown some of my own vegetables in there like tomatoes and peppers. The tunnel environment is very hot in the summer, and sometimes I struggle to get all the beds successfully growing spring flowers because as soon as the sun comes out, it is blazing in there. Spring flowers don’t like it that much when the temps swing up so high, so then they languish in the heat and the weeds begin to set in.
It is a constant struggle with the weeds! So finally–when this patch of nettle popped up, I decided to just go with it. If you can’t beat ‘em, join ‘em, right? If nettles are going to pop up and spread, then why not harvest them a few times, ferment them in a bucket, and spray all those delicious nutrients back onto the plants that I actually want to grow?
While there are recipes for making plant extracts, it doesn’t have to be super scientific. In a nutshell, you just want to harvest the plant material and submerge it in water (preferably rainwater or unchlorinated water; if you have to use city water, fill up a bucket and set it in the sun for a day so the chlorine can evaporate).
Put a lid on the bucket and stir your bubbling brew every day. After a few days, you will start to notice some bubbles as the leaves and stems begin to break down. It will become stinky. Stirring helps cut down on the stink. If you forget to stir, it is no big deal, but it does help prevent mold from forming on the top. If mold does form, just stir it in. You’re not drinking the stuff, after all. The plants are!
After 1 to 2 weeks, your leaves should be fully broken down (i.e. slimy and somewhat reduced to a pulp). Strain out the debris into a new bucket. You will have a dark green liquid extract that you can dilute and spray as a foliar application on plants or as a soil drench.
I like to strain using some metal hardware cloth over a bucket. I also put a cheesecloth over that to catch smaller particles that might clog the pump on my hand sprayer. This usually works pretty well.
Store in a cool, dark place until you’ve used it all up!
Diluting Your Stinging Nettle Extract
I particularly don’t feel like the dilution has to be that scientific, but in order to not burn your plants, particularly if they are young, you should go with a dilution between 1:10 or 1:30 (plant extract : water). The longer you let it ferment, the higher the dilution.
Let’s say you choose to do a 1:20 dilution. That means for every 1 part fertilizer extract you would dilute it in 20 parts water.
You can math that out, and basically for every gallon of fertilizer you want to make, you should add 12.8 tablespoons or 0.8 cups. These are not round numbers, so my inclination is to just add a little extra.
1 cup (16 tablespoons) nettle extract : 1 gallon water
Use this diluted plant extract easily by either applying it to the soil or spraying it on your plants as a foliar fertilizer.
If you notice some burning on the leaves, maybe dilute it further next time. Again, the longer you let it sit, the more you should dilute it.
If you want to apply it to the soil, I would recommend doing a stronger dilution (like 1:10) because there’s some buffering that happens in the soil. By this I mean, some of the extract will leach out through drainage or be held in the soil and utilized by microbes. Not all will be taken up by the plant, so we want to add more nutrients at once.
Fertilize once a week throughout the season. Making other plant extraction fertilizers using different plants may help introduce your plants to other nutrients. Just like we might rotate between herbal teas, tinctures, and food sources, plants will appreciate different nutrient sources as well.
Other species of nettles
Other species of nettles that you may come across are slender nettle (Urtica gracilis or Urtica diocia gracilis) and wood nettle (Laportea canadensis). Slender nettle (a.k.a. American stinging nettle) is very similar to stinging nettle and can be used in a similar way. It does appear to be less viciously armed compared to stinging nettle. This is the native American species, while stinging nettle is the naturalized Eurasian species. Both seemed to be used interchangeably, which is why slender nettle is considered a subspecies in some cases.
Wood nettle is most commonly found in shady areas (hence “wood nettle”). The leaves are wider across, so they are more ovate in shape. The lower leaves are alternate while the upper leaves are opposite. Sometimes the leaves lose their “sting” as they age. This species is also known as Canadian wood nettle. From personal experience, it does seem like the wood nettles do not sting quite as bad when I’ve come across them, and maybe the “itchweed” of my youth may have been wood nettle instead of stinging nettle.
Sources & Further Reading
Bryson, Charles T., & DeFelice, Michael S. (Eds.). (2010). Weeds of the Midwestern United States and Central Canada. University of Georgia Press.
Carpenter, Jeff, & Carpenter, Melanie. (2015). The Organic Medicinal Herb Farmer: The Ultimate Guide to Producing High-Quality Herbs on a Market Scale. Chelsea Green Publishing.
Palmer, Nigel. (2020). The Regenerative Grower’s Guide to Garden Amendments: Using Locally Sourced Materials to Make Mineral and Biological Extracts and Ferments. Chelsea Green Publishing.
Uva, Richard H., Neal, Joseph C., & DiTomaso, Joseph M. (1997). Weeds of the Northeast. Cornell University Press.
