15 most common weeds of Ohio: How to identify and control them
15 most common weeds of Ohio: How to identify and control them
Ohio’s fertile soil is great for lawns and gardens, but it also produces a bumper crop of weeds, from crabgrass, dandelions, and clover to noxious species such as Japanese knotweed.
Identifying which weeds are invading your yard is the first step of lawn care in Columbus, Cincinnati, and across the Buckeye State. Late summer and through fall, weeds to watch out for include ragweed (it’s peak ragweed allergy season now) and crabgrass.
This LawnStarter guide covers the 15 most common Ohio weeds and how to control each one — with tips from weed control experts.
Key Takeaways
- Ohio's fertile soil is prime territory for weeds, from dandelions and crabgrass to invasive species like Japanese knotweed.
- Most Ohio weeds are 1 of 3 types: broadleaf, grassy, or sedges, and controlling each type requires a different control approach.
- Using the right herbicide at the right time in a weed's life cycle is the most effective way to keep weeds from coming back.
Types of Weeds
Types of weeds are classified by appearance as broadleaf (dandelions, clover), grasses (crabgrass, foxtail), or sedges (nutsedge), and by life cycles as annuals, biennials, or perennials.
For annuals, maintaining a thick, healthy lawn is usually enough to keep weeds from being a problem, says David Gardner, a turfgrass science professor at Ohio State University (OSU) who specializes in weed control.
Perennials are best treated in the fall: “Everyone controls in the spring because that’s when they see them — dandelions in bloom, for example,” Gardner says. “But if you see them in the fall, spray them then. You get much longer and more effective control.”
Common Ohio Broadleaf Weeds
1. Dandelion
Dandelions are perennial weeds that thrive in moist soil and sunlight. Their single yellow flowers mature into white, puffball seed heads.
Dandelions are often confused with Canada thistles because of their look-alike leaves, says Bruce Ackley, a weed science and agronomy lecturer at Ohio State University. The spines are what tell them apart.
“Dandelion is the one you step on barefoot and keep walking; Canada thistle is the one you step on barefoot and cuss,” says Ackley, who has coached Ohio State’s Weeds Judging Team for over 20 years.
How to control dandelions: Dig out the deep taproots or use pre-emergent and post-emergent herbicides.
2. Poison Ivy
Poison ivy is a perennial weed recognizable by its glossy three-leaflet clusters. Its oil causes a severe rash with swelling and blistering.
“Never allow poison ivy to climb,” says Hannah Mathers, a horticultural researcher who runs Mathers Environmental Science Services in Columbus. Once it climbs, it becomes harder to kill.
How to get rid of poison ivy: “Roundup Poison Ivy Plus Tough Brush Killer and Ortho Ground Clear Poison Ivy, which contain triclopyr, work well,” says Mathers, who has spent more than 25 years researching herbicide performance.
“You’ll need two applications. Once in the fall, when poison ivy plants are sending nutrients to the roots, she says, “and another in the early spring when new growth appears.”
Wear protective gear and never burn poison ivy, as its smoke can cause breathing issues.
3. Common Ragweed
Ragweed is a summer annual weed that grows up to 6 feet with hairy, triangular leaves. Each ragweed plant can produce 30,000 to 60,000 seeds and will smother your grass and native plants as it takes over the yard.
In Ohio, ragweed allergy starts in early August and can continue until November, with September being the highest pollen month.
How to control ragweed: Use pre- or post-emergent herbicides and mow before flowering.
4. Ground Ivy (aka Creeping Charlie)
This perennial weed thrives in shade and moist soils and is identified by its kidney-shaped leaves and purplish flowers. Ground ivy (or creeping Charlie) forms thick mats that crowd out your grass.
How to get rid of ground ivy: Use post-emergent herbicides for established patches. You can also remove ground ivy by hand or power raking.
5. Stinging Nettle
Stinging nettle thrives in sun and damp, nutrient-rich soil and grows 3 to 6.5 feet tall. This perennial weed can be identified by its sawtooth leaves, stinging hairs, and greenish-white flowers.
How to control stinging nettle: Use herbicides that target the root system or dig out the weed while wearing protective gear. Frequent mowing also helps thin the colony.
6. Yellow Woodsorrel
Yellow woodsorrel, also known as oxalis, has three heart-shaped leaves and small yellow flowers with five petals. This perennial weed contains oxalate, which is toxic to pets in large amounts.
How to get rid of yellow woodsorrel: Apply herbicides containing triclopyr or fluroxypyr. You also can remove young plants by hand. Mulch garden beds to prevent germination.
7. Henbit
Henbit provides pollen for bees and nectar for hummingbirds, but quickly invades thin grass. This winter annual weed has egg-shaped leaves and reddish-purple flowers on square stems, Henbit thrives in cool, moist, shady areas and grows up to 16 inches tall.
How to control henbit: Maintain dense grass as prevention, use post-emergent herbicides during seeding, or hand-pull small plants.
8. Common Blue Violet
Common blue violet is a common perennial ground cover with heart-shaped leaves and purple-blue flowers that can aggressively crowd out your grass. Blue violet prefers partial shade, moist soil, and grows about 4 inches high.
How to control common blue violets: Hand-pulling works early on, but apply post-emergent triclopyr in the fall for established colonies.
9. Common Chickweed
Common chickweed is a cool-season annual with bright green leaves with pointed tips and small white flowers with five deeply divided petals. Each plant produces 25,000 seeds, making early fall or spring treatment critical. Chickweed grows up to 4 inches tall and thrives in moist soil in full sun or partial shade.
How to control chickweed: Use late fall pre-emergent herbicides, post-emergents on seedlings, or manage chickweed through mulching and hand weeding.
10. Japanese Knotweed
Perennial Japanese knotweed can grow 10 feet tall with hollow, bamboo-like stems that can damage foundations and pavement. This weed has oval leaves pointed at the tip and clusters of whitish-green flowers. Japanese knotweed is considered a noxious weed in Ohio.
How to get rid of Japanese knotweed: Eradication is difficult. Mowing and careful herbicide use are necessary, but always bag debris to prevent regrowth and clean equipment afterward.
11. Spurge
Spurge is a summer annual that forms flat mats in sunny, dry areas and is easily identified by the toxic milky sap it releases when its reddish stems are cut. Spurge dies off with the first frost.
How to control spurge: Pull by the roots while wearing gloves or use post-emergent sprays. Prevent spurge’s return with pre-emergents and regular fertilization.
Grass-Like Weeds in Your Ohio Lawn (Including Nutsedge)
12. Crabgrass
Crabgrass is a summer annual weed that thrives in compacted soil, spreading via outward-growing stems and producing up to 150,000 seeds per plant. It is coarse-textured and has a yellow-green color. Its spreading stems grow outward.
How to control crabgrass: The best time to apply crabgrass preventer in Ohio is between mid-March and mid-April when soil temperatures are 50 to 55 degrees.
For existing plants, Gardner suggests mid-July quinclorac applications.
“Big mistake is to spray when you first notice it, which is June,” he says. “That’s a bit too early for our herbicides to work well.”
13. Giant Foxtail
Giant foxtail is a drought-tolerant annual weed that grows 4 feet tall with light green floppy leaves and drooping seed heads that resemble a fox’s tail. Beware: Its seeds have barbs that can burrow into pet skin, causing infection.
How to control giant foxtail: Use early spring pre-emergents or multiple rounds of post-emergent spray, and mow before seed heads form.
14. Annual Bluegrass (Poa Annua)
Not to be confused with Kentucky bluegrass (a perennial), annual bluegrass chokes out grass and goes dormant in summer before seeds germinate in fall.
Identified by boat-shaped leaf tips and greenish-white seed heads, this cool-season annual grows in tufts and signals compacted soil.
How to control annual bluegrass: Aerate your yard to improve soil health, dig up small patches, and apply pre-emergent herbicides in the fall.
15. Yellow Nutsedge
Yellow nutsedge looks like grass but is a sedge that is difficult to remove because it doesn’t respond to standard grass herbicides. Yellow nutsedge regrows from its deep root material, says Ed Nangle, an associate professor in the turfgrass program at Ohio State’s Agricultural Technical Institute in Wooster.
Yellow nutsedge has yellowish-green leaves and triangular stems and golden-brown flower heads.
How to control yellow nutsedge: Nangle recommends herbicides with halosulfuron, noting glyphosate is ineffective due to the plant’s waxy cuticle. If hand-pulling yellow nutsedge, you must dig 10 inches deep and 8 to 10 inches around the plant to remove all roots.
When to Treat Common Ohio Weeds
Pay attention to soil temperatures and plant behavior. A cold spring can push these back a couple of weeks.
If you’ve had a lot of problems with winter annual weeds, consider applying a pre-emergent in late August, Gardner says. “Same ones we use for crabgrass control — pendimethalin, prodiamine, dithiopyr.” Or, treat any emerged winter annuals in the fall when you’re spraying perennial weeds.
The one rule worth remembering: Pre-emergent herbicides go down before weeds sprout, apply post-emergents after they’re up and growing.
FAQs
What Are Ohio’s Prohibited Noxious Weeds?
Ohio’s prohibited noxious weed list includes species such as Canada thistle, poison hemlock, giant hogweed, musk thistle, kudzu, Palmer amaranth and Japanese knotweed, one of the 15 weeds profiled in this article.
Are There Other Less Common Weeds in Ohio?
Yes, purslane, bittercress, white clover, wild carrot (Queen Anne’s lace), and thistle are some other weeds to have on your radar as you’re walking around your lawn.
Which Ohio Weeds Are Dangerous to Pets?
Three common Ohio weeds pose pet risks:
- Yellow woodsorrel: A plant that’s toxic to dogs and cats in large quantities
- Stinging nettle: Causes painful contact rashes
- Giant foxtail: Seeds burrow into skin, eyes, or ears and require veterinary removal
Now You Know How to Get Rid of Ohio Weeds
Ohio weeds can be stubborn, stinging, cause itching, and hurt your pets. Fall pre-emergents will keep most weeds out of your grass, but you’ll likely still need spot treatments to kill particular weeds year-round.
Or you can hire weed control professionals to keep your lawn looking picture-perfect and dandelion-free.
Whatever you decide, it all starts with knowing your Ohio weeds. You have to know your enemies if you’re going to defeat them and keep the intruders from coming back.
This story was produced by LawnStarter and reviewed and distributed by Stacker.
