I have some weeds that keep coming back in my 'blue rug' junipers. I reasearched it a little and found that pre-emergent weed killers are practical, but I am not sure which ones are safe to use on 'blue rug'. Please enlighten me concerning what is safe and what is not when it comes to 'blue rug' and pre-emergent weed killer.
Pre-emergents do not affect existing plantings. They do prevent seeds from germinating. Hence, they would prevent annual grasses from eating your Junipers alive. I use Preen for this purpose.
It is a also very effective against the rapacious annual Japanese stilt grass, which is a noxious invasive exotic weed afflicting the Southeast.