If you're visiting this site from outside of Minnesota, you probably missed this whole 20-Mule Team Borax/creeping charlie thing that's been going on the last five years. Lucky you.
Creeping charlie is the astonishingly perennial "weed" that invades lawns across our state, much to the consternation of otherwise level-headed Minnesotans. Here I am, volunteering four hours of my time on a Saturday afternoon in June, manning the Master Gardener table at a Home Depot, of all god forsaken places, ready to help people choose groundcovers, teach them how to pinch annuals, explain how to prepare soil for rhododendrons, and ninety percent of the questions I get concern ways to get rid of creeping charlie (and does Borax work?).
Look fella, what's the matter with creeping charlie? It blooms a pretty blue about half the season, spreads like mad, grows in sun to part shade, hardy to Zone 1, can't get enough of water, laughs at drought, you can mow it, bury it, divide it, transplant it, and the only thing it will not do is die.
I always contend the nursery industry was asleep at the switch on this one. There's a parallel universe somewhere, where creeping charlie is sold in flats as a groundcover, and a pricey one, at that. It's been hybridized over and over so that new cultivars have been released that bloom in lavender and pink and rose, with names like Creeping Charlene, Stealth, and Charlie's Pride. Perennial Plant Association 2005 Perennial of the Year: Creeping Charlie 'William Shatner.'
But anyway, people hate it. So for a while, the hot remedy for creeping charle was to mix Borax with water, because some gardener in Hastings told the local paper he'd wiped it right out with the stuff.
Well, researchers at the University of Minnesota have concluded that a) done just right, the Borax Solution can control creeping charlie and b) there's enough of a downside to the concoction that they no longer recommend its use.
In minute amounts, boron (the active ingredient in Borax) has a toxic effect on creeping charlie. But it needs to be applied with extreme precision and care, because boron remains immobile in soil, and can quickly accumulate to form a "hot spot" in the lawn, i.e. a spot where nothing grows, including grass.
So the University says, if you try the Borax bit, you can only do two applications per year, for two years, and no more after that. Well, you're not going to knock out creeping charlie with two measly applications in two years. The formula and theory always did have a bit of a Jerry Baker ring to it.
Much better to use real, approved, deadly chemicals made by evil white males employed by major, Republican party-contributing manufacturers, bomb the stuff four times a year (late fall is the one not to forget) and keep on 'er until the accursed weed is gone, gone, gone.
Or, do as my next-door neighbor does. He's been conducting an experiment on Creeping Charlie In The Massive, Rolling Lawn, since the day I moved in. So far as I can tell, it involves doing nothing about it for fifteen years, then seeing what happens.