Troubleshooting: Rotting tree collards

It is so important to me that I can get perennial kale or spinach or tree collards growing.  Perennially growing food of any kind contributes to a community's sense of food security.

The best cultivar of perennial kale/collards/spinach would be Taunton Deane perennial kale, because it's frost hardy, and it survives the winter beautifully.  In fact, it tastes sweeter after a frost.  However, Taunton Deane appears to be prohibited here in our very capitalist, disposable-oriented, cycling-GNP country. :(  So I was stuck with what I could get, which were 2 green and 2 purple cuttings from the Tree Collard Project.  (An excellent organization, worthy of donations, btw.)

Well, I potted my 4 healthy cuttings on Dec 14th.  But last week (9 weeks after potting), I noticed the purple ones wilting and curling.  I tugged on them.  They came out easily--there were no roots!  The ends were rotting, and one was even hollow and squishy at the rotting end.  

Instead of throwing them out, I thought I'd try and save them.  I cut off the rot.  The new ends don't look great, but we'll see.  The one on the left was hard to cut through, and the end looks like I should perhaps cut it shorter to get beyond the rotting... cambium(?).  I wish I knew if you're supposed to do a nodal cutting, internodal cutting, or cut through a node.  

I stuck them in water even though I'm pretty sure they rotted because of soggy, oxygen-deprived contitions in the soil.  Hope they root.  I read that it's possible for them to root in water.  They're too short to do well in soil, so it's a fair gamble.

I tugged on the green ones in their pots but they seem to resist, as if there are some roots already, so they might be doing well.

One of the green ons shared a pot with a purple one so... maybe the problem was that the purple ones didn't like the soil?  Or they're more finicky than the green?  Conundrummed!!

I finally watched this video, and now I think the problem was a combination of too soggy, too little oxygen in the soil, and too cold.

She keeps saying how easy they are to propagate, which is like a knife in my heart each time.  >>>:(

Hmm.  I wonder if the local food bank has a location to grow these.  I'm gonna find out.

Update: March 2nd--the purple cuttings off of which I cut the rotting ends did not survive.  :(  the green ones are still doing well.