There were 25 shoots in total which I planted out in a 5x5 square on Oct 17.
They were quite slow to get started taking 7-8 weeks to get to this point (shown below). As you can see everything else in the garden had taken off before they'd even taken root properly.
I wasn't too worried as I figured most of the activity was happening under the ground. However it still took until February (the height of summer) before they were showing any signs of real vigorous growth...
After it got really hot they were starting to dominate the garden, even sending out laterals across the lawn.
With the weather now starting to cool down I thought it must be time for harvesting, although they reckon the foliage needs to die down first or at least start to turn yellow. It's taken such a long time – 5 1/2 months so far so I couldn't resist digging up a corner of the Kumara patch to see what was happening under the ground. It took quite a bit of digging around before I found anything but I eventually found 2 big tubers which was pretty encouraging.
Unfortunately, it seemed to me there will be maybe only one tuber per seedling planted, so there may not be so many. But they're a reasonable size so I'm pretty happy about. I'll probably be harvesting them in the next week or two so I'll post the results then.