I have come to the conclusion that once the temperature reaches 0C that it doesn’t matter how much lower it gets. Cold is cold! We should be thankful, I suppose, that at least the temperature increases during the day to being quite pleasant, and of course with the intense cold we get these beautiful blue sky days.
The information on Banksias is truly incomplete. Many books will state categorically that particular species will grow only in acid soils. Until they are grown in soils of different pH and tested, we do only have this information to rely on.
I have updated this post with a photo of a Banksia I would like to grow at home. This one is at the Arboretum where pH is closer to neutral.
One of my aims is to try a variety of Banksias, using additional sulphur if necessary. I originally wanted to grow only those plants which grew well in highly alkaline soils. The problem is that I want to see good growth on all the plants and want to intervene if necessary. I will still have the restriction of rainfall to contend with any way. Record keeping is the key to making this a useful exercise.
I certainly want to have Banksia coccinea and Banksia menziesii in the garden.