Another mystery weed - what is it? How do I kill it?
We've had these plants in our yard since moving in 10 years ago and I have no idea what they are. But they are unstoppable and out of control! They resemble the leaves of a lily and spread via underground runners. They never flower. They seem to grow in clumps. The leaves actually get pretty tall - maybe 2-3 feet (the ones in the foreground of this photo were cut off, but you can see the little shoots with long, narrow leaves/blades coming in on either side of the larger clump.)
We had someone come clear out our flowerbed for us on Monday (just pulled weeds, didn't spray) and now it's Friday, and hundreds of these things are already popping up all over. I need to know how to kill them permanently. Any suggestions welcome! Thanks so much!