I plant P. incarnata last year, it looked like it died til I spotted it about 2 feet from where I planted it, it's poppin up everywhere, I just yank out the ones in bad spots and stick em in other plants potted in just plain pottin mix, I usually snip the vines into 8-10" long pieces, I dont cover em but they stay in my greenhouse usually, I'd say 60-75% of em root, it's very humid in there, but the temps swing Wiley in this weather! 110 or higher on a bright hot day, and night time lows will match outside which has been 55-60 here lately...
I don't think the mind that, so I bet humidity is the key... Good luck with that where ur at...
I just give em away, I don't think I'm going to have any shortage of em...
I sure wish more of them were hardy... But I might try pushin their zone hardiness and see what I get
