My 'Limelight' is about 5 feet tall! I don't know what you'd consider a groundcover but this plant gets big. It gets denser than yarrow, for example, and grows upright with no staking necessary. It's pretty much carefree. It is a beautiful plant but it spreads fast, and reseeds. I easily pull out volunteers and keep it in check.

Here's the photo of the 'Oriental Limelight' Artemesia. It's the bush behind the white flowers in the foreground. I don't have any problems with weeds coming up through it.

Thanks for the reply and the picture. I guess I've always seen this plant in small containers at the nurseries and made an assumption. Still don't know where they'll end up but I'll figure out something. BTW, your garden is lovely. I'd like to walk right into that picture and see what's around the bend