Alternating nodes are a sign of "readiness" to flower. Are they getting total darkness?..No light from a window or streelight?..Passing cars?..
Anything that might be disrupting the total darkness.
As far north as you are, they should have been flowering by now.
Hey Stoney..
Outdoors, the flowering hormone starts to build as the plant senses "longer nights". Some "early" strains begin to react with as little as 9-10 hours of dark. Once the 'hormone' has built to a critical level, flowering starts. The 12 hour rule really only stands "true" of "equatorial sativas" in the outdoors.
Most of the indica crosses that everyone has these days mature by mid October @ 35-37N.