In the past week, I’ve taken a run at eliminating a pretty, but particularly annoying, weed from my garden: Hairy bittercress (Cardamine hirsuta). This early in the season, its clusters of dainty white flowers look lacy and particularly decorative. Flowers are especially prevalent in the garden in cool weather, from mid to late spring, although this plant will bloom through much of the season provided plants have adequate moisture. Flowers arise from a mound of pinnate (featherlike) leaves with small rounded leaflets, and the plant springs up everywhere that moist soil occurs, including containers and mulched garden beds.
Innocent looking hairy bittercress in the garden.
How could I possibly identify this small, innocuous plant as my enemy du jour? In another week or two, the flowers from the main spring crop will fade and seed will ripen. Trying to pull plants with ripe seed is simply an exercise in futility. The authors of Weeds of the Northeast describe them as “explosively dehiscent, propelling seeds over 3m.” That’s nearly 10 feet, so pulling seedlings—or even walking through a patch of plants—is basically an exercise in seed distribution. So far, getting angry at the little boogers hasn’t helped at all, so I’m on a pulling mission.
When I’m weeding, I tend to focus on a single species. In this case, eliminating flowering plants cuts back on seeds for next year’s garden. Theme weeding also means I don’t have to change tools from plant to plant: Weeds like dandelions and wild onions require a gardening knife for digging, while hairy bittercress can just be pulled and tossed into a collection basket. (It does mean I have to go back over the beds again, though.) And while my aim is eradication, I know that’s impossible. In reality, I’ll just cut down on the hairy bittercress next season, but that’s good enough for me!
A day’s weeding. More planned for tomorrow!
Eastern Shore Gardener 
Oh, how I detest these boogers! They were the focus of last evening’s work.
Cherylie
I agree completely! At least if you get them early in the season they don’t spew seeds everywhere when you pull them!
Is there a problem with pulling this in it’s beginning flowering stage and simply leaving it to decompose on top of the soil?
Terry
If the plant hasn’t set any seeds yet, it’s fine to just toss it back onto the soil, since pulling will kill the plant before seeds can mature.
This is certainly timely! Very warm here in CA yesterday and I was trying to eradicate baby’s breathe. What a job! Pulling out the old ones had me covered with seeds and dispersing them (probably) all over the yard even more. So sorry we ever planted that one small container!
Hi Clare! The seeds spreading everywhere are what make the bittercress so aggravating! I know I’ll need to go over the garden again for other weeds, but getting rid of lots of the bittercress (not all, by any means) before the seeds fly, was really worth it. Barbara
Now I finally know what this stuff is!! If I know names of my major weeds, maybe I will be more determined to get rid of them, cursing all the while!! Still, in this warmth, the garden is growing inches every day — the good stuff along with the weeds. Thanks for all of your advice over the years, Barbara.
Hi Joel!
I often don’t know the names of the weeds I’m pulling, and I’m not sure if that would speed up my eradication efforts. When I do a blitz against one species, though, I do try to identify it. Plus writing a blog about the garden makes me more committed to identify them as well!
Barbara
Can these also have yellow flowers? I believe that I also have this in my garden in Okinawa, Japan, but the flowers are not white.
Jen
Hairy bittercress only has white flowers, but it’s in the mustard family (Brassicaceae) and is therefore closely related to quite a few other similar-looking plants that have yellow flowers. The four-petaled flowers arranged in a cross shape are characteristic of mustard-family members. A couple of yellow-flowered plants that are similar are marsh yellowcress (Rorippa islandica), field pennycress (Thlapsi arvense), and wild mustard (Brassica kaber). These are all larger than the bittercress, and there are others. So, after all this, the short answer is you probably have a relative of bittercress. The good news is you can take care of it the same way: by pulling up the plants before they self sow.