When curcuma like this go dormant, the rhizome itself will not be pulling any water from the soil at all, so watering is not needed. It doesn't hurt occasionally to lightly water the pot only to prevent the soil from overdrying the rhizome. For me its usually not a problem since we are in a high humidity climate, arizona would be different of course. If you only have a few rhizomes/pots to deal with, you can always unpot the rhizomes when they are completely dormant. They can be stored indoors in a partially opened box, bag, etc. This allows some air movement to prevent rotting, but also prevents them from drying out too much.

As far as what to do now, stop watering for sure, as the plant is done for the season and in nature it would be very dry by now. When the stem is completely dry as well as the pot you can store either the pot/rhizome until spring.

Tim Chapman

Tim gave you good advice.
Mike

Tim, is the pacific northwest known for rotting curcuma or is it just my experience? I tried the edible grocery store type and it rotted, then came back. This year I green housed it for more protection.

I assume from the rest of your post that the plant didn't rot but went dormant over winter. I don't know how well Curcuma and zingiber do in the PNW, but Hedychium seem to be the best suited to the climate. Roscoe and Cautleya will do well there also. I haven't heard too much from people trying to grow other genera, but have heard that things like curcuma don't do as well in the ground probably due to the much shorter growing season and milder summer temps.

Zingiber officinale which is what I assume you bought at the grocery store is also naturally deciduous. It may be forced to stay up year round in the greenhouse, but in the end that will only weaken the plant.

Tim Chapman

Tim, the grocery store I got the root from has a lot of weird rhimozomes. They have the regular ginger(Z.officinale), taro root, Thai ginger(huge yellowish rhimozomes), and tumeric root(which is the one I was referring to) Is it a curcuma? I would have to second the asessment of them not doing well in the short season if it is a curcuma.
Thank you very much for the info on gingers that might do well here.
Happy Hoildays!