So, naturally, I felt a deep, profound sense of botanical inadequacy when I tracked down a legendary giant rose bush hiding behind a quaint little history museum. The rose bush at the Rose Tree Museum in Tombstone, Arizona, holds an official Guinness World Record for being the largest rose bush on the planet, with a canopy measuring approximately 8,000 square feet, and some estimates pushing that figure closer to 9,000 square feet during peak growth seasons. Stepping Into The Courtyard GardenWalking through the entrance of the Rose Tree Museum and into the courtyard feels like stepping through a doorway into a completely different world. Practical Tips For Visiting The Rose Tree MuseumGetting the most out of your visit starts with knowing the basics. The Rose Tree Museum is open Monday through Saturday from 9 am to 5 pm and on Sundays from 10:30 am to 5 pm.