Hairy bittercress (Cardamine hirsuta) is an annual weed that can quickly invade gardens and lawns in early spring. With its fast growth and prolific seed production, hairy bittercress can take over bare patches of soil and become a persistent headache for gardeners. Luckily, there are several effective control methods to stop hairy bittercress in its tracks and reclaim your landscape.
Identifying Hairy Bittercress
The first step in managing hairy bittercress is learning to identify it. This opportunistic weed is in the mustard family and emerges in late winter or early spring when soil temperatures are still cool.
It starts as a rosette of pinnately compound, rounded leaves at the base of the plant. The leaves are alternately arranged along delicate, light green stems that can grow 3-10 inches tall. Small, white flowers with four petals bloom at the tips of the upright stems. After flowering, skinny seed pods form that explosively shoot seeds in all directions when ripe.
Why is Hairy Bittercress a Problem?
A few factors make hairy bittercress such a nuisance:
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It grows quickly in cool weather before other plants break dormancy. This allows it to carpet areas of bare soil
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Prolific seed production means each plant can spread hundreds of offspring.
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Taproots make manual removal ineffective if you leave any root fragments behind. The plant resprouts readily.
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Explosive seed dispersal flings seeds far from the parent plant, spreading infestations rapidly.
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Hairy bittercress shades out and competes with desirable plants, stealing water, nutrients, and light.
Cultural Control of Hairy Bittercress
Cultural practices that promote vigorous lawn growth are a critical first line of defense against hairy bittercress:
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Overseed thin areas in the fall to fill in bare patches where bittercress often first appears.
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Fertilize the lawn in early fall and spring to help the grass crowd out weeds.
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Mow frequently once bittercress flowers to prevent seed production.
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Apply corn gluten meal in fall to inhibit bittercress seed germination without harming established turfgrass.
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Use 2-3 inches of mulch around landscape plantings to block light from reaching bittercress seeds.
Manual Removal of Hairy Bittercress
Hand pulling hairy bittercress can be effective IF the entire taproot is removed. Use a long, narrow tool to loosen the soil and pull out the whole plant. Go slow and remove every piece of root to prevent resprouting. Manual removal works best for young plants before heavy seed set.
Herbicides for Hairy Bittercress Control
Herbicides provide a more aggressive approach if hairy bittercress is extensive. Preemergence and postemergence options are available:
Preemergence Herbicides
Apply these to soil in late summer/fall to prevent hairy bittercress germination:
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Dithiopyr – Dimension, Dithiopyr
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Dimethenamid – Tower
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Sulfentrazone + Prodiamine – Echelon
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Isoxaben – Gallery
Postemergence Herbicides
Spray these directly on existing bittercress plants for control:
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2,4-D, clopyralid, dicamba – Millennium Ultra
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2,4-D, fluroxypyr, dicamba – Escalade 2
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Carfentrazone + quinclorac – SquareOne
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Sulfentrazone – Surepyc, Dismiss Turf Herbicide
When using postemergence herbicides, timing is critical to treat hairy bittercress before it goes to seed. Always follow label directions carefully.
Ongoing Prevention of Hairy Bittercress
Bittercress management requires persistence, but a diligent, multi-pronged approach can provide effective control:
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Maintain a dense, healthy lawn through proper mowing, fertilization, irrigation, and overseeding.
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Use preemergence herbicides on invasive-prone areas in the fall.
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Hand pull small infestations and spot spray with postemergence herbicides.
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Continue monitoring and treat promptly at the first sign of hairy bittercress.
Early intervention is vital – don’t allow bittercress to flower and set seed. Combining good cultural practices with judicious use of herbicides provides the best chance of getting hairy bittercress under control long-term. With a rigorous prevention plan, you can reclaim your lawn and garden from this aggressive annual invader.
Getting to know hairy bittercress
End of winter through spring is when hairy bittercress is most prominent. By then, those fall-sprouted plants have grown into three- to four-inch-tall clumps or “rosettes” with stems that have small, rounded, green leaves. The leaves are arranged alternately up the stems.
The trouble starts when wiry stalks begin poking up six to eight inches above the clumps and start forming dainty white flowers at the tips. Within days to weeks, the flowers mature into long, narrow, purplish seed pods that contain the weed’s seeds. Not only are these pods prolific seed producers, they shoot the seeds up to several feet away when touched or blown by a breeze.
Hairy bittercress typically dies and disappears by summer, but by then, the seeds are safely settled over the ground, where they can remain viable for years.
Hairy bittercress will grow in sun or shade and everywhere from garden beds and lawns to woods, meadows, and roadsides. It especially thrives in cool, damp weather.
How to weed out Hairy Bittercress
FAQ
What product kills hairy bittercress?
| Active ingredients | Product name(s)* |
|---|---|
| 2,4-D, MCPP, dicamba, and carfentrazone-ethyl | SpeedZone |
| 2,4-D, quinclorac, and dicamba | Quincept; 2DQ Herbicide |
| 2,4-D, triclopyr, and fluroxypyr | Momentum FX2 |
| amicarbizone | Xonerate |
Does vinegar kill hairy bittercress?
Controlling Hairy Bittercress
Or, you can cut off the tops of young seedlings with a hoe and remove them from the soil surface. Apply mulch after weeding to prevent further germination. If you prefer to use an organic herbicide, horticultural vinegar with a small amount of orange oil will top-kill bittercress.
What is the problem with hairy bittercress?
It Spreads Like Wildfire. Once hairy bittercress matures, it produces long, narrow seed pods that are essentially nature’s catapults. As soon as they’re dry, even a light touch (from mowing, walking, or wind) triggers them to explode and shoot seeds up to 3–5 feet away.
How to prevent hairy bittercress?
A preemergent applied in late summer/early fall can help prevent hairy bittercress from germinating, however, you will not be able to sow grass seed. Or spot treat actively growing weeds with a liquid, selective, postemergent, broadleaf weed killer in the spring before it goes to seed (photo at top of page).
Can hairy bittercress be wiped out?
While heavy-duty chemicals may be needed for shrubby woody perennial weeds, hairy bittercress can be wiped out with significantly weaker chemicals. The key is applying it at the right time and using the correct application rate for the weeds you are fighting.
How do I prevent hairy bittercress seeds from germinating?
Also helpful is a late-season application of Preen Extended Control Weed Preventer, which prevents hairy bittercress seeds from germinating for up to six months. Ideal timing is late summer to early fall – just before hairy bittercress starts to germinate.
How do I get rid of hairy bittercress?
Mulching and herbicides have their place among management strategies as well. Regardless of method, the golden rule in your fight against hairy bittercress is to not let it germinate. Acting early is critical; once this weed seeds, it can spread at an alarming rate, complicating your control efforts significantly.
Does hairy bittercress kill weeds?
Hairy bittercress plants in garden beds also can be spot-sprayed with non-selective, kill-everything herbicides or with herbicides labeled for control of broadleaf weeds. (Check to be sure hairy bittercress is included on the label list of weeds controlled).
When is the best time to get rid of hairy bittercress?
Answer: The best time to control hairy bittercress is in the early spring before it flowers and sets seed. By catching the weed early, you can prevent it from spreading further. Concern 6: Will pulling hairy bittercress by hand be effective?
How do you remove hairy bittercress weeds?
Apply a mulch to the surface after weeding to prevent further germination. Use contact weedkiller to kill seedlings and young plants before they grow and get a chance to flower. Discover how to remove hairy bittercress (Cardamine hirsuta) weeds, using organic or chemical methods, from the experts at BBC Gardeners’ World Magazine.