Grasses overflowing boundaries

[v3ggiemuffin]

I have a large fountain grass on one side of my house. It’s growing in a space where a bit of the concrete path was removed by the gas company. There is a curb surrounding the plant and this year some of the grass is coming up between the crack between the curb and the rest of the concrete. I thought about pouring vinegar or boiling water into the place where these upstarts are coming out.

My question is if that would also kill the main plant, since the offshoot is certainly coming from there.

 

[Marck]

Greetings, welcome to the Forums.

Fountain Grasses (Cenchrus spp., formerly Pennisetum spp.) will often reseed. It is more likely that plant coming up in the concrete path is a seedling rather than a rhizomatous offshoot. It would be good to post a picture of the plant to judge the distance between the two plants, and also for identification purposes.

In any case, pouring strong vinegar or boiling water on the plant may be effective if the liquid can penetrate into the crack deeply.
It isn't likely to seriously damage the other, larger plant, but this partly depends on how close the two are to each other.
another option is to keep pulling or clipping away at the visible part of the unwanted plant until its energy reserves are exhausted.