Buddleia "trees" in zone 5

Is there anyway to keep a buddleia from dying all the way back to the ground, maybe with a lot of mulch?

I ask based on this thread http://davesgarden.com/forums/t/617593/ where they discuss making a treelike (standard) shaped buddleia like this one http://www.gardengatemagazine.com/extras/46buddlejastandard.php The one in the picture is a weeping one. I saw a couple non-weeping ones in a local nursery this weekend that were about 5 feet tall and grown in the tree shape. The guy there said they were grown in Oklahoma though.

Does anyone in this region have any tips on getting a treelike buddleia in zone 5 or colder?

Thanks,

Maureen

My experience with these plants is somewhat limited, but the only ones I have ever seen that didn't die back to the ground in zone 5 is in conservatories like at Powell Gardens. These plants have been kept in the greenhouse much of the year so do not get exposed to our winter temps.

What I'm reading agrees with what you say. I may make an attempt to put extra insulation on one of mine this year and see if that keeps it from dying all the way back, but I think the tree shape will be a very hard thing to maintain here.

Thanks,

Maureen

I don't think mulch will help in zone 5. I sometimes leave the branches on for winter interest, but it grows new shoots at the height it wants to from the base. It only blooms on new wood here.

Well, maybe I could insulate it with something more, like a tarp. I also have one growing in a pot and I think I'll bring it into my garage and see if I can keep it from dying all the way back.

Keep us posted on your results!