Your Petunia Tree reminds of these. I think it is in British Columbia, Canada......but there is a place called Victoria Harbor.....and they are known for just absolutly gigantic hanging flower baskets. From what i have read about them, they average on the line of 3 to 4 feet across and with trailing foliage, 3 to 4 feet tall. 
 
In other words - They are HUGE. 
 
Here's a picture of them