Q. The most pernicious weed I have ever encountered in my 50 years of gardening has invaded my soil. The only garden center in the Philadelphia area that even knew of it told me there is absolutely nothing anyone can do to get rid of it except sift every inch of soil to remove all the rhizomes. I have spent hours doing this and they continue to roar back. The "flower" is a variation of a cobra head with a thin purple thread-like stem emanating from the hood (in and of itself very sinister looking). Its scientific name is Pinellia. Please help me with this!"
- ---Susan Miller; greater Philadelphia
A. Major mea culpa! We received this plaintive plea way back in 2011, and we're using it today (we have a lot more recent emails about this weed to choose from) because I owe Susan a major league apology. And wrapped in that apology is a warning to all gardeners—especially clueless men like me.
Let's begin with the bright answer I sent poor Susan back then: "Geez—you mean the one that looks like a little Jack in the Pulpit? I think they're neat. I had a few show up this season and they pulled out easily from wet soil; so I left a few to look at...."
Now, as I have said in the past, I do the same with lots of so-called 'weeds'—like mullein, because the yellow flowers on their giant spikes attract lots of pollinators. And I'm always raving about my wine berries; some members of my family prefer the juicy fruits of this alien invasive to REAL raspberries! And the flowers on lots of other 'so-called' weeds attract beneficial insects and pollinators.
Most importantly, I've always been able to keep these theoretically 'bad plants' under control. A few seasons of low-level clump pulling after heavy rains even got rid of all my wild onion and garlic—which I didn't care about one way or the other.
So what's so special about this plant? A baby Jack in the Pulpit sounds pretty cute; right? Well, it IS cute the first couple of years. That's part of the problem! Because, as Madeleine in Chestnut Hill, PA wrote in an email last month, "they become HORRIBLE. Sun, shade, dry or wet—they flourish anywhere. Pulling doesn't work, because they grow from tiny little bulbs. Mulching doesn't work; they poke right through. And I hear that herbicides are a waste of time."
Hey! But they were cute! I love real Jack in the Pulpits, and never seem to have enough of them come up. And these little ones were cute!
And now? Now I wish I had heeded those warnings. You know the enchanted broomstick Mickey battles in Fantasia? A slacker. This weed reproduces MUCH faster. And it seems to have its timing down. The first couple of years there's just a few of the little cuties in your garden. Then—BOOM!—all of a sudden it's your new ground cover.
Luckily, it's just in my raised beds—where weeds are easy to pull, thanks to 20 years of compost and me never stepping on the soil. I can't imagine what a flat-earth gardener would do; these things would be impossible to pull from typically compacted soil.
Just pull them very sloooowly. As our Pinellia plagued listeners have noted, there's a little bulb underneath the plant instead of a traditional root system—and the stalk that connects them is really thin and fragile. You pull on it the least bit wrong and it snaps.
So my helper Matt and I have been pulling them slooowly; repeatedly hoeing them; and mulching them heavily. For the first couple of months it didn't seem to matter, but now we're seeing the 'rope a dope' effect—keep removing the leaves and any underground bulbs you miss while pulling will weaken over time. And they're vulnerable to the other controls we've advocated for "bulbing weeds", like Star of Bethlehem and wild onion and garlic.
My first recommendation for attacking this weed in a wet year or month would be a tool called the Water Powered Weeder—or something similar, like an adjustable nozzle with a super-sharp setting; anything that shoots a laser-like stream of water into the soil right at the root zone to pop them out.
During a dry spell, I'd suggest trying one of the new herbicides whose active ingredient is iron; they're very effective on weeds with nice big leaves like this. Drenching them with herbicidal soaps at High Noon on a hot day should also work well. And toasting them to a crisp with a flame weeder during dry times should be effective and emotionally satisfying.
But the most important tactic is prevention—don't be a dummy like me and ignore the advance scouts when they first pop up! If you see a cute little 'Jack' in your garden, wipe it out! On day one! And Susan: I am SO sorry I didn't listen to your warning!
(You know, I always say that men learn much more from failure than from success. So this episode makes me a bona fide genius!)