I live in seattle, where mom nature loves to water heavily all year round with the exception of about 3 summer months. I have 3 BC's and they do just fine with my standard soil of a third each of pummice, volcanic, akadama( standard for my pines.) I put low numbered organic fertilizer in tea bags, end of june thru september so they get small amounts each time i water. What I've learned over the years is careful repotting with minimal root disturbance. don't fertilize heavily or too early. I love my whitebarks that refine up so nice. and am working to improve my skills with limber. They're much more course. (frowns)
I get lots of visitors to my display garden and bristlecones are my favorite as they always draw a comment regarding they're white pine pitch on the needles as if they have some kind of disease. LOL