switching set up for my bp

[Slim]

Thanks everyone! I was wondering how many holes should I start with I'm in Michigan and the humidity in my room likes to stay around 40 to 50%

Start out with about half as many as you think you might need, and adjust from there. You can always add more, but if you have too many you'll need to tape them over. Better to start out with too few than too many.

Is there a rule of thumb for growth speed of bp's?

No, they all grow at their own rate.