Blue is a wonderful color in the garden. Not those plants that are called blue but are really lavender, purple or some other color, but those that are truly blue. This is one of those. Salvia ulinginosa, Bog Sage, starts blooming here mid-summer and continues until frost. It is a tall plant, maybe 4 feet in a spot it likes and can be floppy sometimes. It isn't totally reliably hardy here, sometimes coming back and sometimes not - and never early, but it does reseed so you're likely to see it, if not in the exact same place the next year, at least close. The blooms don't have any fragrance, but I do see butterflies on it, so that's another reason to grow it. We've been growing it for about 5 years and will probably always have some here if for no other reason than to have a bit of blue in the garden.