Duncan's nursery is also in a part of Canada with very mild winters, North Saanich, BC, which a short 25 minutes away from Victoria, on Vancouver Island, and surrounded by plenty of water on all sides. By Canadian standards, this area is virtually downright subtropical (or at least as close to "subtropical" as it gets in Canada).
Some of that area very close to the water in Vancouver island is even designated to be in climate zone 9b, if you can believe that. Although it's a very "cold" climate zone 9b that doesn't see very much warm temperatures, and has very low cool temperatures for most of the year.
North Saanich is actually designated to be in 9a. Although that might be a tiny bit misleading because just 2 days out of the year they can also have nights that are more like the ones you would find in 8b, and occasionally during rare storms they will get temperatures that are closer to 8a. I know that was the case in the 2018-2019 winter from someone I was communicating with from Salt Spring Island (which happens to be just north of North Sannich).
He grows palms and eucalyptus trees, big ornamental Basjoo banana plants; and last I heard was experimenting with a semi-edible banana called Helen's Hybrid, but that didn't end up surviving that year due to the unusually cold temperatures that year, during a 3-day stretch in February.
That area (referring to Salt Spring Island and the east coast side of the southern part of Vancouver Island) got as cold at that time that year as the far south end of the Puget Sound did (down to Olympia) even though most winters that area does not get as cold.