Garry I think youll struggle when the plants reach 2 metres high.
Whats going to stop them falling over long before that?
Im growing in Sydney and this years crop is looking like heaps compared to the first one last year.
Main worry is avoiding frost and then sheltering from wind.
When they were smaller I surrounded them with shade cloth on all sides and above overnight in winter.
From about year 2 on I removed the top cover and now theyre at 2 metres tall the side wind breaks are long gone.