Today's featured Weekly Weeder plant is common ragweed, Ambrosia artemisiifolia.
Common ragweed is also known as ragweed, hayfever weed, bitterweed, bloodweed, crownweed, mayweed and bane of allergy sufferers everywhere. Some other common ragweed species include bur ragweed, giant ragweed and western ragweed. Western ragweed is a perennial.
The seeds of this amazing plant can lie dormant in the soil for 40 years, waiting to be unearthed to spread truckloads of tiny pollen grains EVERYWHERE. Plus – bonus – changing weather patterns have extended the ragweed season through much of the United States. (BTW, just for the record, the climate has been changing as long as the planet's been around. The weather has raised and toppled empires – but that's another post.)
Range and Identification of Common Ragweed
Where Does Common Ragweed Grow?
Common ragweed is native to North America, and is found throughout the United States and most of Canada (See USDA map below). (Aren't we lucky?) It has also spread over much of Europe, where it has become a problematic invasive species.
Ragweed thrives where other plant struggle – wastelands, vacant lots, aged pastures, stubble fields and other disturbed soils. Where drought or poor soil moisture transfer make potassium unavailable, conditions favor ragweed growth. Common ragweed is an annual, but as noted above, it produces thousands of seeds that last virtually forever. Up to 32,000 seeds have been recorded on a single plant. DON'T LET THESE THINGS GO TO SEED!
What does Common Ragweed look like?
The individual leaves are fern-like. It looks pretty innocent when it's small.
Ragweed stems are fuzzy, and the green flowers appear on spikes with their own set of leaves above an existing leaf. The stems are filled, not hollow. It prefers full sun, disturbed and slightly acidic soil, and can tolerate (and thrive in) drought.
Ragweed as Food and Habitat for Wildlife
Believe it or not, ragweed is useful. It produce seeds that are rich in oil and provide winter food for birds and small mammals. Fairfax County Public schools website states that “Ragweed is a good source of food and cover for wildlife. Eastern Cottontails eat the plants, and insects, such as grasshoppers, eat the leaves. Some animals which eat ragweed seeds include: Meadow Vole, Dark-eyed Junco, Brown-headed Cowbird, Northern Bobwhite, Purple Finch, Mourning Dove, American Goldfinch, and Red-bellied Woodpecker.”
Note: Ragweed will give milk an “off” flavor, so ragweed control in pastures is advised. (See below.)
Common Ragweed = Allergy Trigger
Some studies indicate that ragweed produces up to 90% of the allergy causing pollen in the United States.
If you are one of the folks who is bothered by ragweed pollen, unfortunately there is no cure. I've noticed that when I watch my diet (plenty of fat to keep nasal and lung membranes well lubricated, plenty of live culture foods, less sugar), my allergy symptoms are much milder. For more help, see 15 Home Remedies for Seasonal Allergies and Hay Fever Symptoms.
I found out that direct skin contact with ragweed plants can cause mild contact dermatitis, after pulling quite a number of ragweed plants bare handed from the side of the driveway. DernNet NZ confirms I'm not the only one with this reaction. About a day and a half after pulling weeds, I woke up with a palm full of small, itchy bumps. I put some plantain oil on the irritated skin and the itching subsided.
Medicinal Use of Common Ragweed
Judith C. Evans states in her article “History and Medicinal Uses of Ragweed”:
Ragweed’s medicinal properties include: astringent, antiseptic, emetic, emollient, and febrifuge. Early American physicians recognized ragweed’s medicinal uses, and Native Americans valued it as a topical and internal remedy. Healers and herbalists prepare remedies from the roots and leaves. Crush the leaves and apply the juice to soothe insect bites and poison ivy rashes. Native Americans prepared a poultice from crushed leaves to relieve swelling and prevent infection.
Ragweed also provides aid for internal ailments. Herbalists value ragweed root tea as a remedy for nausea, fevers, and menstrual disorders; Native Americans used the root tea as a laxative. For years, Ozark herbalists have treated diarrhea with tea prepared from the leaves. Ragweed pollen is used in homeopathic remedies for treatment of hay fever symptoms.
I would suggest care with internal use of ragweed, especially if you have any type of allergic reaction to the pollen. Next time I get a mosquito bite, I may try the sap to see if it does indeed soothe the itch.
In the book “Weeds: Control Without Poisons“, the author notes that ragweeds proliferate where drought and lack of moisture availability in the soil makes potassium unavailable. Hardpan, gravel, compacted soils, crusty soils are all prime ragweed territory. As soil improves, other plants will likely out-compete the ragweed.
In my yard and garden, the usual soil measures (adding compost and organic fertilizers, mulching) have virtually eliminated the ragweed. The primary spots we still see it are around the edge of the driveway, and on compacted, dry soils. For control in fields and pastures, “Weeds: Control Without Poisons” specifies:
“Ragweed out of control can be managed with manganese, copper, , vitamins C and B-12, calcium, phosphate and sugar in a solution, recipe to be worked out on-scene according to test readings.”
The author also encourages tillage and mowing to knock back the growth.
The word “weeds” often has a negative connotation, but I think of them simply as plants not purposefully planted. They are often useful, and fill a spot where something needs to grow. (If you don't plant, Mother nature will.)
Our weeds hold the soil in place, plow compacted subsoil, draw up nutrients, provide medicine, feed wildlife (and people) – they are a treasure, not a curse. As you tend your yard and garden and the soil improves, unwanted volunteers will either disappear on their own, or be much easier to manage.
- Wildflowers of Wisconsin
- Nature's Garden: A Guide to Identifying, Harvesting, and Preparing Edible Wild Plants
- The Forager's Harvest: A Guide to Identifying, Harvesting, and Preparing Edible Wild Plants
- Backyard Foraging: 65 Familiar Plants You Didn’t Know You Could Eat
- Edible Wild Plants: Wild Foods From Dirt To Plate
Thanks so much for stopping by to visit. Help stop the overuse of herbicides by spreading the word about putting our weeds to work and sharing this post.
You may also find useful:
- Top 10 Edible Flowers, Plus Over 60 More Flowers You Can Eat
- The Weekly Weeder Series
- My Favorite Wildcrafting Resources
Originally published in 2011, updated in 2017.