I did that last year with some standard red geranium/pelargonium (it was me buying at Wal-Mart, who knows what it is?). I had read to soak the roots once a month as well. Um, have I mentioned that I tend to forget? I managed to remember to soak them twice between October and May. Out of I think 4 root bundles (or whatever they are called), only one came back, but it never bloomed even though it was put in the same place it bloomed in last summer. I may have brought it out of dormancy late, though; that's what I keep telling myself. That's my experience.
I also read recently that cutting them back and watering them is instructing them to grow NOW, which is not what we want them to do. I think that person suggested to leave it in the pot of dirt in a dark cool spot, and in Feb/March give it a drink, and when you see some growth then start treating it like you normally would again, gradually introducing it to light, that type of thing. That's my plan... my problem is right now:
As of today it still has green leaves on it, as do my ivy pelargonium which I want to try to overwinter dormant as well, and I'm trying to decide what to do now.... I'm getting a little tired of moving them in and out every night (temps are really low 30s at night but mid 50s in the day).
Would putting them in the (cooler and dark) garage now force them into dormancy, or just kill them because they didn't go dormant first?
Watching this thread with interest....