I think you're trying too hard. Sugarcane shouldn't be that hard to propagate from fresh cane. Recently, I purchased some
fresh cane (a piece about 6.5 feet high). I merely cut it into pieces about one foot in length and stuck them in a potted plant (a parlor palm). In about a month or so, I tugged at the cane and noticed they can rooted. I pulled them all out and planted them in a somewhat sandy soil. I guess bottom heat wouldn't hurt (but I didn't use it)--they all rooted at room temp during February. Could it be that your cane isn't fresh enough? PS. Don't use the zip lock bag, I bet your cane is rotting from excessive humidity and lack of adequate air circulation!

That is good to hear, thank you! Perhaps my cane wasn't fresh enough last time... it was during winter when I purchased it - who knows where they got it from! I'll try again - I do have a source for bottom heat (a seedling mat), so I think I'll put them in a pot on that, but without the ziplock bag. Thank you very much for all your suggestions!! :)

The only question I have left then is - how do I know which end is up? The piece doesn't have a taper... Thanks :)
A

I'm not sure it really matters. I believe you're supposed to plant them horizontally (I never do). I always plant them vertically and only bury about a third of the cane (when you buy a piece that's 6-7 feet, it's pretty obvious which end is up). The cane was then cut into sections about a foot in length. I aim for soil that is only slightly moist (I didn't water at all for the month that it was rooting in--it was a large container with a host plant for company). A sandy, loose soil is probably best. I have found the freshest cane sold in Asian or Hispanic markets. Good luck!

Just had to tell you, your ideas worked, it has started to root!!!! I was so excited when I saw the rootlets last night that I yelled and scared my husband :)
Thanks!!