NOT VERY LONG AT ALL....THE FIRST YEAR MAYBE 4 FOOT AND THE SECOND OVER 6 IF YOU DONT TRIM IT BACK
How long does it take rose of sharon to get 6 feet tall?
For a Rose of Sharon (Hibiscus Syriacus) your looking at roughly a growth rate of about 8-10 inches a year maxing out at 11-13 depending on the type of season we've had in reguards to how quickly it warms up and how slowly it cools down. If you bought it at its standard height roughly 2.5' to 3' it would take about 3-4 years to reach 6 ft and if you bought a small one in say a 6 inch pot around 12" tall it would take about 5-6 years. Good Luck