Well, I'm no expert by any means, but I've now had a few titanum go through dormancy without any hassles so I will give you my limited experience. First, with my potting mix in my climate (indoor culture) I water around every 3 days to keep the mix just a touch damp. They get fertilized every time they get water. When they go dormant I dig them out (I've never had rot so far....knock on wood!!!!) and immediately repot in new, fresh mix. I then water perhaps once every 7-10 days to keep the soil at the level of the tuber just the tiniest bit damp. Mine have only stayed dormant for a max of 1 month and for as little as 2 weeks (the new roots were emerging by the time I unpotted it after dormancy). Some people in the tropics say to use peat in their mix for Amorphs....I can tell you that will rot mine in a heartbeat....I say this only to make a point.....the conditions you will want to use are likely very different than mine since your climate is sooooo different. My hewitii get a lot more water than my titanum and I do not stop watering when they go dormant....so far I've had many of these go through dormancy without a problem. I do not think you will have a problem, but if you get rot then you need to adjust your conditions since this should not happen. I hope someone from the tropics can comment for you :o) Dan

Mate,
Dan has hit it on the head. I'm no expert either but I have been growing A. titanum in the tropics for 5 years. I use a very well drained, soilless mix and water nearly every day. Mine are in nearly full sun under the protection of sparse palm leaves high above. They get fed, heavily, every three or so days or when I start to feel guilty about not feeding them. Their favourite feed is the dirty water from fishtank water changes. Alternatively they get a mix of seasol, liquid potash and trace elements. Sounds like a lot of hassle but just think how big those tubers are growing.
I do have peat in my mix. doesn't seem to hurt them. Mine don't seem to actually go dormant but when they drop their leaves I move them away from the automatic sprinklers and water them by hand when they start to dry out. Mine drop their leaves and almost immediately start to bud again. I re-pot them into fresh mix every season.
Mine are all in pots so far but I am about to put some little ones in the ground soon.
I hope this helps,
BC