I'll just copy what I wrote in a similar thread, and add... GOOD LUCK!! I've told this story several times- I had two ancient Paulownia tomentosas removed from the front yard of our new house in May of '07- before we even moved in. I felt terrible that our new neighbor's first impressions of us were as tree killers, but it simply had to be done! As much as I hate killing a tree, I am not a criminal. The criminal is the IDIOT THAT PLANTED the damned things. I had the roots ground out as deep as the largest grinder would go. The roots shoots that came up that year were horrendous- one every foot covering the entire yard. It was literally a daily chore to keep up with them- you'd cut them all then the next morning there would be another hundred of them 2 inches tall. They came up again equally as bad in '08, all spring and summer. In '09 they slowed down a bit on my property but began seeking new areas as I saw them in neighbor yards as well- not only on the adjoining properties but across the street. Spring and summer of '10- three full years since I had the trees taken out- and I still got shoots. THREE YEARS! They slowed down considerably but I still had to cut down one or two every couple of days. They are impossible to pull. They are one tenacious tree. AND... I cut more root shoots in the spring of '11!!! Four. Full. Years. After the trees were removed. This tree is the devil!!! This is the very first year I have not seen one- five full years of diligently patrolling the yard with scissors to cut root shoots. In a way you're gotta respect that degree of the will to live!

There are numerous reasons not to plant a flowering pear. They are short lived and weak wooded. This may not seem like something to be concerned about NOW but they in fact do grow rapidly, not slowly, and in a matter of years, not decades, you will be taking bids from tree services to remove it/them or parts of it/them. There are people who have reported branches of these falling on persons or property leading to injury and expensive damages. Again, doesn't seem like a concern now but it will be at some point. The last thing you want is a whole bunch of these lining your driveway. Particularly in areas that get wind or ice. In my area, they leaf out during late winter which makes them prone to wind damage during our spring thrunderstorms. These pears are also an invasive species in much of the country meaning they have escaped home gardens and started taking over natural areas, displacing native plants. They may not be an invasive species where you live but just by purchasing one, you are supporting a grower who will in turn grow more and more and ship them to areas where they are a problem. When in bloom the flowers smell very bad. As the trees mature the offensive odor drifts. These trees are no longer used by tree enthusiasts or experienced landscapers or urban foresters for these reasons. So don't buy one at a garden center or anywhere else for that matter. Do yourself a favor and cut down the one you have before it turns into an expensive problem. Flowering pears are a waste of money, a waste of time, and a waste of space. Rather than planting a tree that will self destruct in 5 years, plant a tree that will still there in 100 years. Something that will truly add value to not only your home but to the environment as well. Long lived trees don't usually have the prettiest flowers but that what flowering shrubs are for.

See if you can order some live ambrosia beetles. They help the paulownias along real nice. Just put some pheromones on the trunk and apply the beetles to the trunk and watch your paulownia turn into a beautiful and valuable shade tree. This only works with royal empress trees tho so don't try it on anything else.

Twelve feet is not an adequate crown clearance for either tree. Catalpa's tend to have wide crotch angles and you'd be pruning before it ever got tall enough to shade the garage. Don't even go there with Paulownia. I am a five/six cusp. I have a few of them I got for the juvenile leaves and just let rip. I knew better, but did it anyway. Mine have bloomed numerous times in mild winters, but the last few winters have been mild enough they are seeding volunteers. Not supposed to here. The blooms are hard to see from the ground, only to be enjoyed from a distance. The pods shed and are a mess, and the first frost the leaves just drop in big sheets, no fall change. Branches weak. Weed tree.