The gout weed. Ick!

Hi & welcome to Gardenweb! Congrats on your new house.

It doesn't look like there's enough sun there for the lilac to be great. I would work on propagating it, then put it out of its' misery when you've get a new one going well. Lilac does only bloom for a short time in the spring, so even in lower light, this one may be able to continue doing that indefinitely if you want to keep it there to "see how it does" each spring. If you trim it a lot, it may likely be inspired to grow a bunch of new suckers from the ground. That may or may not appeal to you.

I've not dealt with bishop weed in grass before. I'd probably try smothering it.

Not sure that hedge is the kind that should be trimmed. I might ask about that on the shrubs forum first.

Thanks so much! The lilac does get more sun for most of the day, that shot was late in the evening.
I think I will leave it, I like it there. And I will try to "suffocate" the weed. A vinegar solution seemed to kill it well in the backyard but I don't want to mess with the lilac roots in that way.

Bishop weed is notoriously difficult to kill, so go industrial with your smother, like multiple layers of cardboard, a thick, heavy layer of mulch to hold it firmly against the soil. A few sheets of newspaper won't do the job on that one. The benefit of using something that will decompose is that it doesn't have to be removed, and is not impermeable to moisture penetration. It will also conform to every groove and dip in the soil surface, which blocks the light completely, and the air and the very space needed for leaves to grow. (Starting a new planting area this way fits under the "lasagna" umbrella of methods.)

I might use the smothering to eliminate mowing all the way to the corner, looks tight between the lilac and house. Then use some kind of border, bricks or landscape timbers, to keep the grass separated from that area. Next year, check under the smother. If you find no signs of life, you should be able to add some other plants there, whatever perennials, annuals you might like in your new flower bed. Just make sure to make the holes all the way through the cardboard if it has not fully decomposed.

My concern about the light wasn't from the amount of it visible in the pic, but from the combination of things surrounding it, the structure of the lilac, and that it looks like it's to the north of the house/other shrubs, and under the eave from that angle. If you start new shrubs with pieces trimmed from this one, you could put them in other spots that get more light, to have some great lilacs since this one is in a less than optimal spot. Not an unattractive plant, just not able to fully perform there.

Everybody does not do it the same way, have the same opinions or goals, so definitely take the info and use it to make your yard the way you like it.

That looks like the same kind that makes a great tree, although commonly sheared into a shrub or hedge.