Question
Hi, I have a back yard beginning to be taken over by ground ivy , what can I do to get rid of this problem in my yard. I have kentucky bluegrass and I live in Detroit,mi.

Answer
The non-profit Garden Organic website of the Henry Doubleday Research Association posts a page on 'Glechoma hederacea' (formerly 'Nepeta hederacea'), aka 'Creeping Charlie', a ubiquitous American headache:

www.gardenorganic.org.uk/organicweeds/weed_information/weed.php?id=83

And it is here that they note: 'There is some evidence that Ground Ivy can have an allelopathic effect on the plants around it.'

That 'allelopathic effect' is one of this plant's secret weapons.  Some people consider it a desirable groundcover.  But most of us see it as an invasive Weed we'd rather see less of.

Allelopathy is usually a defense mechanism that first got attention in the 1930s.  It's been studied in the Black Walnut (whose roots, leaves, stems and nuts generate the Allelochemical 'Hydrojuglone') and Oak (which release 'Coumarins') Trees, in Japonica rice (exactly how is still not understood, but possibly the team effort of a cocktail of phytotoxins), in Coffee plants (Caffeine is an Allelochemical known to retard and eventually halt growth even in older Coffee plantations), Pinetrees, Nutgrass and the noxious Tree of Heaven (Ailanthone and other powerful compounds secreted mainly by its roots).

All these plants produce chemicals intended (usually) to stop competing species from growing nearby.

Allelopathic Caffeine (aka '1,3,7-trimethylxanthine'), produced by Coffee and a handful of other plants, also makes Bacteria and Fungi sick, and it makes some Insects sterile.

Some aromatic plants emit Benzoic and Cinnamic Acids, which stop competing plants from absorbing Phosphorus or Potassium.

Salvia officinalis, which is the Sage used to flavor turkey at Thanksgiving, will severely reduce the germination of Perennial Rye, but planted next to Coffee Plants, it revved up CO2 fixation and photosynthesis, and, ultimately, it actually produced better tasting Coffee.

When G. hederacea (your 'Ground Ivy') was interplanted with Radishes in one study back in 1987, growth in Radishes increased.  Dead Ground Ivy leaves boosted shoot growth more than 1000 percent.  I kid you not.

Start with physical removal of as much of this stuff as possible.   A Thatch Rake will amass a surprisingly large quantity of this stuff, thanks to the connecting stolons.

I stumbled recently on the abstract of a study done in 1987 and published in a French scientific journal.  It concluded that Ground Ivy grows more sparsely in Perennial Rye Lawns that are thick and mowed Tall.  But the same Ground Ivy also expands its reach, as if to escape the Grass-packed area.

So, when Spring arrives and it's time to start mowing again, set the level higher, and get out the Thatch Rake to pull up the spreading vines.  You'll get it under control quickly, although probably not permanently.

University of Minnesota came up with a homemade borax solution that is tricky, but still TOTALLY effective against Ground Ivy, a few years ago:

www.extension.umn.edu/info-u/plants/BG522.html

Be cautious about drenching the surrounding Grass with Borax.  Note their warning: 'If it's applied repeatedly or at too strong a rate, you will end up with an area where you can't grow anything until the Boron leaches out. That may take years.'

That's state-of-the-art Ground Ivy/Creeping Charlie science as of today.  But there's PLENTY going on behind the scenes.  Keep me posted, and I'll keep you alerted on any breakthroughs.  Thanks for writing.

THE LONG ISLAND GARDENER