Driving down the road and see this AMAZING "WEED" growing on the edge of the road, in the Seattle Area. Just had to stop and get photos of this, it is Gianormous! Stands about 8 to 10 feet tall, each of these flower bunches are about 8 to 12 inches. Would really like to know what, why and how this is so spectacular! Any clues?

Butterfly Bush/Buddleja. Butterfly Bush (Buddleja davidii)

For what it's worth, it is classified as a noxious weed in the state of Washington.

It's available at many nurseries and online. Many colors are available. Some are invasive while others are sterile.

Yes! That is it! So amazing that it is just growing on the side of the road, no houses anywhere around, just some power station. Thanks for the ID! Wow! Noxious Weed? Found it here: http://www.invasivespecies.wa....

Not all are invasive. Years ago we had 14 of them but they all self-seeded much too easily so they had to be deleted. Now, one volunteer - a courtesy of the birds, has been in the same place for about seven years and it doesn't give me any grief or any volunteers. Black Knight was my favorite of all and a big butterfly attractant. Butterfly Bush (Buddleja davidii 'Black Knight')

It is a butterfly weed, considered desirable by most. I love them but have had zero luck at over wintering them, they don't come back for me

Let's not conflate two terms that have different meanings. "Invasive" is a imprecisely defined word, but gardeners generally use it to describe plants that spread around their yards more than they would like. "Noxious weed" is a legal term applied to plants that cause significant ecological and/or economic damage. Laws vary from state to state, but it's generally illegal to grow plants that have been designated as noxious, in which a case, how it behaves in a given person's yard is irrelevant.

Designating a plant as invasive is usually a sad occasion because they are almost always plants that most people do love dearly, and have been moved around by gardeners a great deal, and then escaped into wild areas. When non-native escapees are so successful that they displace native plant populations, they are designated as invasive. Sterile means a plant can't make seeds. Why there would ever be any BB's for sale that are not sterile is a mystery to me. I'd recommend a sterile BB to anyone who gardens where they are hardy.

This is a pretty neat looking plant, definitely reminds me a a Lilac, but I get that if it is an invasive species. I was up in the mountains a few years back and found some huge area of large trees/shrubs near a logging clearcut, that were thick and beautiful with what I recall is a very similar if not the same flower. Again, I thought it was amazing and in our area of the world most everything grows like it is from the Garden of Eden. If this is in full bloom, I am going to have to go on a hike this weekend and see if I cannot find it again and post some pics.

Sounds like fun! And everybody loves pics. ;)

This is called a Butterfly Bush in the south and iIt is not invasive here. They are sold in nurseries and butterflies do like the flowers.

I live in eastern WA and I didn't see it on my county's noxious weed list. They sell them at the nurseries around here and I've never seen them in the ditches or other wild areas. I've planted a few over the years and they don't seem to be too long-lived for me.

The key is whether or not they are able to make seeds (whether or not the plant is sterile.) If a plant can't make seeds, it can't spread and is harmless.

My Mom put a seed making one in her yard (same town as me) and it was not well behaved. After a few yrs, there was a patch of them, I dug them out.

The Great Butterfly Bush Debate:

http://www.naba.org/pubs/bg172...

For gardeners whose property borders a non-forested natural area, use the sterile or low fertility cultivars or remove the seed heads in the fall before they open. Many of the modern cultivars of Buddleia davidii have dramatically reduced fertility and are not invasive. Some hybrid cultivars (such as Buddleia 'Blue Chip') are almost completely sterile and pose no threat. Some low viability selections include Buddleia weyeriana, Buddleia fallowiana, Buddleia hemsleyana, Buddleia longifolia, Buddleia macrostachya, and Buddleia nivea.
From:
http://www.plantdelights.com/A...

AND from our own NGA:
http://garden.org/learn/articl...