Hi Charles/Kirpi,
I have been growing Hurst Greenshaft for the past 5 years and in my experience they do grow to around 4′ 6″- 5′ and perhaps a little more.
I use a 3′ 6″ support frames and add an 18″ extension as they grow and they went well above that this year (the wall on the right is 9″ cavity block). This pic was taken after they had been battered by unexpected strong winds before I got a chance to add the frame extension.
The row on the right were module sown on 10th April and planted out on 30th April. The row on the left were also module sown 28th May and planted out on 16th June. The pic was taken on 24th July.
I have to module sow as I have a bad mouse problem around my plot – despite having 3 cats!!
