Looking at photos such as: ...it seems different from Eupatorium capillifolium. The stems on my plant are smooth, with no hair, and the "leaf" sections are thinner, almost tubular, with less of an orderly fern-like structure to each leaf section (sorry I don't know the proper terms to use). Here's more of a close-up:

its big because it is in a garden bed with good soil ... it really doesnt need encouragement .. lol .. it gets 3 foot in plain old sand never watered .. weeds really.. really ... respond to good soil ... do NOT let it seed .. or you will rue the day ... but its not rue ... ken

Yes,possibly Rue. Ruta graveolens. But the leaf shape is slightly atypical. It's about to flower now, that's why it has those elongated stems. Can you show us when it does so? Can you see if the foliage has a pungent smell? Wash you hands afterwards - some people are sensitive.

Check Sunset Western Garden Book to see where you are zoned by them and what Sunset zoning they give for this tree. Since as I mentioned the flower buds may be damaged even over here in the Seattle area it seems doubtful this species is going to work out well as a flowering tree for you. Also if yours does manage to develop and flower regularly, set seed then you will have the problem of it dropping hard woody seed capsules on the grass. And producing deep shade. Many trees and shrubs originating in E Asia, that have gone wild in the similarly wet summer conditions of E North America do not behave in the same manner in the dry summers of most of W North America. In my area paulownia seedlings are seen only sporadically and in small numbers in particular situations where they are able to be sheltered from drought. Such as among large rocks or in frequently watered garden borders. I have never seen one out in the woods here, and Boise is much drier than we are.