Thanks Rhino! I mixed a lot of perlite into the FFHF, getting close to the 40% that ResDog recommends. When I watered from the top on transplant I heard the res fill pretty easily so I don't get the feeling that the soil mix was too dense. I run FFHF straight out of the bag for my cloth bags and this SIP mix was much more porous.
Well, we're learning at Shed's expense. Thanks Shed! lol.
I too have experienced stalled plants when transplanted late. Many, many of them if I include vegetable starts. I can only raise so many seedlings in my SIP-like seedling system, but I always germinate extras. Being a moron, I often waste resources on these extras instead of killing them off, and in every event that I have transplanted these into actual SIPs they stall. If I plant them quite late, say, after 4-5 nodes, they stall practically for an eternity.
I have investigated some of these eternal stallers and also found root rot - even though substantial aeration was provided. I think the roots simply die from entropy, that is, by not constantly growing they become an easy target for fungi that are otherwise controlled by growth, and the dynamic environment it creates. I mean, roots grow so fast you can
see it live if you commit. It's reasonable that the
absence of such growth may be also be very dramatic, in its own unseen way.
As a guess, I suspect an epi-genetic scenario, specifically, that the genetically communicated feature, 'hydrotropism' is epigenetically stifled by these specific environmental conditions, but that's a wild speculation I will personally never have the tools to prove, nor qualifications to properly understand.
Shed's transplant doesn't seem to have been terribly late, however, and I think he made efforts at least to bottom water, which is significant and helps. I do suspect that drought/deluge watering routines are a contributing factor here, regardless the direction, but again, I can't prove it.
Anyway, Shedster, I'm happy to provide whatever anecdotal experience I have if you come up with any specific queries. However, you've got so much experience with canna, and good instincts, that I'll follow with great interest nonetheless.