Trachycarpus princeps cold hardiness
So far, there is no conclusive summing-up about the cold hardiness of Trachycarpus princeps as even the biggest cultivated one is no less than half meter trunk , too early to test its maximum hardiness and few available ones are planted out to present a solid demonstration.
Some say it got damage at 15F but small plants have been tested from -9.5C in UK to -15C(5F) in Alabama ,USA and Netherlands and Germany without any problem.
See the links
The following is a screen shot from the Dutch forum.
A German guy grew the seedling directly in the ground and as I was told they survived the cold as -12C with only sawdust covered around it.
Sounds crazy to the German bitter winter.
T.princeps grows on the cliffs of 1600-2100m above the sea level and the snow could be up to knees in winter as I was told when traveling there. My assumption is that they could be as hardy as T.fortunei if not more. It takes time to test this idea.
But some other factors may play a role in its hardiness of T.princeps
First of all, high humidity in winter may worsen the cold harm.
Second, at younger age, all Trachycarpus are not that cold hardy as adult ones and The current available T.princeps are mostly seedlings and so it is natural that we did see some report about the cold damage to it while learning good news about its surprising hardiness.
Thirdly, whether the plant is strong and healthy makes a difference in the cold resistance.
Anyhow some Americans have been growing T.princeps possibly for years
May you guys share your own growing experience so that we could have a full picture of this elegant palm.