Horntoad said:I've always tried to encourage it, not control so I have no idea.
I do that too if it's in the right location. It's extraordinarily attractive as a plant. Nice foliage, a true blue bloom, not subject to insect damage. It would be an ideal plant if it weren't for its habit of growing everywhere including places where it's not welcome. I find it so attractive that it's not a plant that has ever gotten much effort toward eradicating. I always have spots of it that look like this one in the photo.
