I've started to lift some of the A. konjac.They aren't going dormant yet but I'll lift several a few weeks early to play it safe. Here are a few photos of an interesting one.

New growth point directly under petiole caused it to split.
Early season rot? Heeled over and firm to the touch.

Hi,
I think the rot is probably last years tuber. Someone will correct me if I'm wrong, but I think the plant consumes the old tuber and a new one develops underneath.
Konjac can take frost so i always let mine die down naturally. I even had a few offsets that were left in the ground last fall come up this spring (in south central WI) --we had a VERY mild winter though.
Mike

Hi Mike,
Thanks for the input. I've read several different accounts of how big the tuber needs to be before an inflorescence might form. My largest tuber so far is ~4.5" wide. What has your experience been?

Next year I'll plant some of the larger tubers deeper and see if they'll overwinter outdoors. I'm thinking 8 to 10" deep. Last year was very mild here too with only one sub-zero night and one other down to zero. This without snow cover. I actually had three Z. albomaculata I missed survive!

Hi Evan,
I would guess somewhere in the 6" range would be blooming size -- probably another year.
If you leave them out I think the key would be cold but dry --cold and wet would rot for sure.
Mike

Thanks Mike. Last fall we were cold and wet. I lifted after 1st frost and several of the tubers had some rot. Maybe in a raised bed with amendments to enhance drainage they'll consistently overwinter.

I took one of my A. konjac tubers, looking lonely sitting on a shelf and placed it in with the remains of some potting mix in my mixing tub. The mix was pretty dry and I covered the tuber. After 7-10 days I took a look at the tuber today.
Lots of new roots