Could very well be poa trivialis. It likes shade and damp areas. In the summer, without water or with too much heat, it'll go dormant or die. It is a spreading perennial. Certainty is a selective control BUT NOT for TTTF, unfortunately. There may be others out there though. I know some studies have shown ethofumesate to be more effective at controlling poa triv than poa annua but others have shown no control whatsoever. There is probably no good chemical control for you. In the spring, does this grass develop thick stalks?

TJ, You may already be completely aware of this, but just in case you're not, invasiveness doesn't necessarily correspond to what you can see in your own yard. In other words, a plant could be extremely invasive (environmentally damaging by displacing native flora and fauna) and still not express serious aggressive tendencies in your yard. Seedlings could be eating your neighbors woods up without appearing in your own yard. Aggressive plants are not necessarily invasive (even if exotic), and invasive plant don't always appear (at least in the immediate vicinity of the plant) aggressive. The only reason I mention this is because you said that's what you had been "seeing". I'm not saying I think you have anything to worry about in the case of this species.

I received 3 helianthus "lemon queen" for mother's day. Unfortunately 2 of them didn't make it, but the 3rd one did... just barely. Seems, as the plant was just taking off, a ball from over the fence broke most of it off. It has since regrown but hasn't bloomed yet. I also just received 2 replacements from the company my daughter bought the originals from and will plant them as soon as it stops raining. (I may just have to build an ark if it doesn't stop soon!) I've also acquired some Boltonia from a neighbor and bought a black sambucus. Let's see... from seed I started some perennial sunflowers and heliopsis. Most of the new perennials did pretty good this first year but I imagine they'll do even better in the coming years! In the meantime, to fill in the gaps until the perennials fill out I planted tithonia, annual sunflowers, along with scarlet runner beans. Next spring I'm going to transplant a clematis too. All in all it was a successful year keeping the little darlings at bay. They've also made friends in the neighborhood and, now that they're a little older, mom lets them go to the friends' houses so most of the time they're gone. Peace at last. Thanks to everyone for their suggestions!

Have had mint, monarda, obedient plant with little to no problems. Campanula punctata reseeds but cute so I remove most of it in spring and leave few clumps. Macleya cordata reseeds, easy to pull. Bishop weed was planted because of my own stupidity- still trying to get rid of it but the bed full of bulbs and perennials so it is pretty hard to remove it completely. Chameleon plant died on me- I wanted it to grow. Petasites japonicus was speading last year with alarming speed- well, got killed this year during recent cold snap- barely found couple survivors and potted them up. Got some running bamboo last year- it is marginally hardy for me...