Blue hardy ageratum can be a very vigorous grower but its
lavender blue bloom comes as such a surprise in the late
summer. Mine is one of about half a dozen different plants I have that are from my mother's garden. She passed away in 1990 and stopped gardening about 1985. The places it works best for me are the foot of a steep hill which gets about 4-5 hours of sun, front edging of a border in similar sun, and in a very shady area under overlapping coverage of two sugar maples. In the shady area it has less color, is shorter but brings a lavendar blue fluff when nothing else is blooming in a hosta,fern bed. Chris

it grows wild in the next county, all along fence rows. I seldom see any here. If I had some, I would plant it where it can spread, because it does.

Blue Mistflower (Conoclinium coelestinum) sometimes called Eupatorium coelestinum.

Nell

Here is a link that might be useful: Hardy Ageratum

I have it, and yes, every seed grows, but you can hoe it out...and hoe it and hoe it... :)
When I was out walking a few days ago, I saw hundreds of little seedlings throughout the flower bed. The time is NOW to cultivate them out!

{{gwi:642961}}

But I LOVE it. It is beautiful.

~ Annie

Thanks to everyone.

I think I will keep it. I do love the way it looks and it isn't very hard to pull up or hoe out. I saw where P. Allen Smith liked it so I guess it is a keeper.

I have it and it does come up everywhere, but I haven't found it to really be a problem. If I like where it plants itself I leave it. If it isn't in a good place I just pull it. It isn't hard to pull. It hasn't crowded out anything and seems to do best in kind of bare spots where I need something anyway. I've had some croak in the heat though. I like it.

I have it and love it! I bought 6 little plants from Bluestone in 2007. This summer, it was everywhere that I wanted it to be. It was easy to just scoop up the seedlings and move them around. In my large garden, it is welcome to spread. It doesn't seem to have deep roots and other plants (like bee balm) can grow up through it.

It's the mass of blue along the right side of the path... eventually, I will have more of it as it spreads. This is from August and it bloomed quite a long time. {{gwi:642962}}From Defining Your Home Garden

I love drying this flower. Dries a true blue, so you can enjoy it all winter.

It's one of my favorites,too. I'm down to a small patch nowadays, so I should think about digging some starts and spreading it around. Normally, they self seed pretty well, tho.