During the landing flare on the uphill runway of the private grass airstrip, the airplane encountered a quartering tailwind gust causing it to shift left of the centerline. The pilot applied corrective control inputs avoiding a ditch; however, the left horizontal stabilizer struck a rock berm. The airplane sustained substantial damage to the horizontal stabilizer and elevator during the accident sequence. The pilot reported no preimpact mechanical malfunctions or failures with the airplane that would have precluded normal operation. The airstrip was comprised of grass and gravel, and was wet at the time of the accident.