i gave up on these in my MI ... rather short lived plants due to our winters ...

that said.. i dont think i have ever seen an 8 to 10 foot plant ...is this possible??? .. though i am sure.. the warmer the zone.. the bigger the plants might get ...

when i look at this link.. i dont see many that seem 10 feet tall ...

https://duckduckgo.com/?q=Buddleia+height&t=ffcm&iar=images&iax=images&ia=images

of course.. they can be pruned to any width requirements ... usually with shrubs.. they tend to be as wide as tall ... [but not always] ....but you could properly prune it to width ...

there are a number of things called butterfly bush.. plant.. weed.. just to be sure ..... are we talking about Buddleia?

ken

"i dont think i have ever seen an 8 to 10 foot plant ...is this possible???"

Yes!! Butterfly bushes - Buddleia - are really small trees in my climate. It is not unusual to see them 12-15' tall, sometimes taller. However in colder zones, where they are not yet considered invasive, they do tend to die back in winter so as noted, the height in your CT location may never achieve that 8-10' desired.

Spread of ones that have been able to keep stems, build up to a 10 ft height is also likely to be greater than height, rather than the other way around - a 10 ft tall one is not going to be only 5 ft across.

Yes, some examples of this plant have gotten 20 ft tall in the Seattle area. Where it pops up just about wherever there is good sun exposure and bare dirt, gravel or a stone surface.

For some reason, I find the white variety more hardy. And yes, they can get tall but the most mine has gotten is probably five feet.

I just thought about this. Years ago at an herb and perennial nursery which is really a farm with various gardens, there was a brand new (to me) shrub growing near a building. It was VERY tall and was being swarmed by butterflies. I was told it was a buddleia. This was before the shrub was as common as it is today. I have never seen one, at least in my area, ever again that tall. Plus it's no longer growing at this nursery altho I remember it being there for quite a few years. So I do believe butterfly bushes can grow beyond 5 or 6 feet.

I will talk to the family who run the nursery to make sure I'm remembering right. Unfortunately they only stay open April thru June now.

I lost one butterfly bush this year due to the cold, but my other two survived. The one that didn't make it was planted last spring so it probably didn't have time to settle in before the coid winter.

My largest is about 10' high and 6' in diameter but I do a bit of trimming during the season to keep it in check. Every spring I hard prune it to about 2' high and it magically grows like gangbusters back to 10'.

The industry has spent a lot of time producing smaller bushes for those that don't have the space. I have one of those too. It grows about 4' high.

I was thinking a deep purple, but I might try a white one.