I grow or have grown them here in the southern hemisphere , which im guessing your also in giving what youve said ,Well it was more a hypothetical project (for others to try) as I don't see a whole lot of benefit in creating a perrenial variety for my needs.
I have pretty mild winters here so am personally more interested in developing a strain to grow over the winter months. So far it's been a successful experiment
Seeds were germinated mid-late May, flowering iniatiated late June and harvest was mid to late August. Yields were low and flowers were airy but suprisingly with a decent level of trichomes and nice aroma.
I left some lowers to see if the plant would survive over the winter. They still look "alive" but don't appear to be growing. It's already warmed up here and equinox is just a few weeks a way so hopefully we'll see some new growth soon
but im at 17 degrees from the equator , so on the coast it could barely be called winter , however at 920 metres where i live we get some winter , 6 to 8 weeks at least of cool to cold nights , and some cold days too depending on the wind and level of cloud ,
anyhow from the solstice onwards seems to be fine , keeping in mind we have november storms that will ruin buds and make them reveg ,
we allowed 16 weeks , from seed to harvest , which is about right most of the time for hybrids where i live ,
so definitely its doable ,, i think the biggest hurdle is short days really , mine are 11 hours at the minimum ...
those plants harvested in october and november , if i left a few branches on the bottoms will reveg and grow much larger than the first time ,
i think this is the sort of thing that perennial cannabis stories come from , so yes they will regrow into a larger plant on a second run and can be harvested if the monsoon isnt too harsh , but that all occurs within a year cycle ... so certainly not perennial or even biannual ..