N. rowanae was rediscovered by a guy called Rod Kruger, who has just set up the Captive Exotics website. Rod grows a number of rowanae variants, as well as a huge number of Australian mirabilis variants. It is quite a sight to many huge rowanae plants in one greenhouse.
This species is showing a few cultivational differences to Australian mirabilis. I've been experimenting with some plants Rod sent me, and I've discovered that this species can be quite temperamental.
From Rod's experience, he notes the following traits. Firstly, it does not grow easily from cuttings. Cuttings start to shoot, then often die several months later, sometimes 75% of cuttings can fail. Secondly, they often don't flower every year, but every 2 to 3 years, which makes obtaining seed more of a challenge than usual.
From my experiences, I note the following. Seedlings travel well, but cuttings don't unless they're very well established. Further, rowanae does not appreciate cool day temperatures. It will happily cope with cold nights provided the days get very warm, but if you have cool days, the mortality rate is high. I've found this plant touchier than bicalcarata when it comes to cold weather.
I would recommend this species to growers who have a heated lowland set-up. If you can't provide it with constant heat, I would recommend against it to avoid heartache.
Some of the Australian mirabilis variants are also really spectacular, but I've found them much easier to grow.