If someone sugegsts to you that you should go rock climbing on Mount Garibaldi, then they might be trying to get rid of you.
Its rock is expressly the worst of all of that on the Pacific Coast stratovolcanoes. "The ridges and faces are shattered, and rocks regularly rumble down its flanks without apparent provocation" (note in "Summit Guide to the Cascade Volcanoes"). It seems to me that "ridges and faces" means "the whole mountain". There`s not much else to a mountain than ridges and faces!
So wait instead for a cold, dry spell in late autumn or winter. And take your chance with avalanches instead.