Our back fence (an iron bar fence) borders a golf course, and between us and the fairway is about 50 feet of "native" landscaping. This mostly means long, native grass (some type of crab grass?).
Unfortunately, next to one section of my backyard, a large patch of thistle grew up very tall a few years ago. While thistle can turn out very pretty...
... it's also terrible when even small growth appears in my lawn. Given how spiky it is, bare feet is not a good idea.
I ended up spraying weed-killer on this patch and got it mostly knocked down. However, the bits that had already spread to my lawn have come back year after year. They don't go away when I spray with lawn-safe weed killer, and I even had Tru-Green service for a while and nothing they did was successful either.
I have tried pulling them out by hand, but our lawn, unique soil (solid clay), and the toughness of the root system makes most of them simply break off at the soil, leaving them to come back in just a few weeks.
Is there anything I haven't tried? Or should I just keep trying to dig them out by hand?
Note: since I've been more attentive to the patch on the other side of my fence, and it hasn't gone to seed in a couple years, the weeds have stayed confined to about 200 sq. feet of my lawn.
Lawn type: Kentucky Bluegrass
Climate: Semi-arid (grass growing season is about March/April to October/November)