Answer: Paulownia tomentosa, the Empress Tree, will flower in your area and should not need winter protection. It's a fast-growing tree to 40' or 50', but don't expect the advertised 10' of growth per year! A more realistic expectation is 2'-3' per year. Empress trees grow best in full sunshine, with summer irrigation. They are not picky about soil and usually do not need feeding. The trees will cast very heavy shade, and have lots of surface roots, so place your tree where it can grow without compromise, and don't plan to garden directly under it.
Lombardy Poplars and other hybrid Poplars are in fact very fast growing trees. I certainly do not consider them "weed trees". I think they get a bad wrap because their limbs break off very easily in high winds, and in the tree world, they don't have an extremely long life. Some other fast growing trees include Silver Maples, Honey Locust, Willows, Northern Hackberry, and Mulberry.
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