Chironex

The one thing I will say is that it is not so much the height of the pseudostem, (merely an indicator of root development) as it is the ability of the plant to become established well enough. This would seem to play a role in true hardiness.

To illustrate, let's say an acorn germinates late in the summer and doesn't have time to harden-off adequately before the first frost. Chances are that it will not return in the spring. On the other hand a more well-established seedling that germinated in spring and has established its roots better, will probably return.

Where the true zone hardiness lies, is beyond me. There is another thread talking about this same thing. Check that to see what other results have been posted.

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Scot