Page ContentMaps and Directions Sienna Plantation Clinic7010 Highway 6Missouri City, TX 77459713-442-6700 (Clinic)713-442-6767 (Pharmacy) Heading South on Hwy. 6 from Hwy. 59: Take Hwy. 6 South. (Note: There is an entrance off of Hwy. 6 right into the clinic parking lot – this is directly before Oilfield Road.) OR Turn right on Oilfield Road. Next right is the entrance to Sienna Plantation Clinic.Heading North on Hwy. 6 from Hwy. 288: Take Hwy. 6 North. Turn left on Oilfield Road. Entrance to Sienna Plantation Clinic is immediately on your right.