Corralling The Lysimachia 'Firecracker'

I recently wrote about what I thought was Coreopsis 'Golden Gain' invading the neighboring plants.  I discovered it was actually Lysimachia "Firecracker' (thank you Gardenweb Forum), which is a VERY invasive plant.  It seems to be a type of Loosestrife, which is a real invasive family.

It had suddenly spread into some stokesia on one side and into some asters in the back.  It had totally smothered a patch of Coreopsis 'Moonbeam'.  It has fibrous matted roots that are impossible to disentangle from other plants.

It was sold to me as the Coreopsis 'Golden Gain' and since it had a golden flower, I didn't realize I had been sent a mislabelled plant.  Fortunately, the vendor is making it as right as they can by sending replacements.

Still, I had to do a lot of hard work to correct the situation.  As it actually IS a rather good looking perennial, I wanted to keep what I could.  If I had a sunny spot surrounded by paved surfaces to fence it in (like driveway/sidewalk/house) I would have dug it up and moved it there.  But I don't.

So my solution was to dig up the plants in the invaded area, install edging barrier around it, and replant the lost stokesia and asters.  Looking back, I am thinking I should have just used Roundup!  But all's well that ends well...

First, I dug up a foot around the area I wanted to keep, a nice 8' diameter circle.  It was just like digging up turf sod and about as much fun.  I am saving the dug up sod because I have an idea what to do with it!

Here is one side cleared out.  Digging around the soaker hoses was not fun, but pulling them up through the existing plants and trying to nestle them back down afterwards seemed worse.

Here is a picture of them invading the asters in the back of the garden.  They seem to spread the roots out 2' in Fall, then the new stems emerge suddenly in Spring.  You don't get much warning.  Last year, I thought they were self-sowing, so I snipped the flowerheads.  Alas, that wasn't the problem...

After I dug them all out leaving the 8' circle, I dug a trench around them.  Since they haven't spread under the path edging, I think more edging will contain them.  It took a spade to cut through the matted roots, a mattock to dredge the trench, and a trowel to scoop out the soil.  Loads of fun...

I threaded some old edging under the hoses through the trench...

And backfilled on both sides.  The edging looks high, but that's because I removed a lot of soil with the dug pieces.  I will have to add more soil to return it to level.  The edging should be sticking about 1/2" above ground.  Mulch will cover that.

You can just see the space for the 3 replacement stokesia to go.

Any Lysimachia that try to escape the edging will get a vinegar spray first, and a Roundup spray if absolutely required.  And if the edging really won't stop it, I will make a cardboard circle around it and give the whole patch the Roundup!  I'm taking a chance even giving these plants a second chance.  But if they will stay in bounds, they'll have long happy lives.

Now what am I going to do with the parts I dug up?  Future post!