I'm worried they will stay small , is there eny simple whey to slow down this process , they are outside.

Take your time... we need a picture of the actual plant, not some generic photo off the web! They will all stretch when they get into flower... my Blackberry Moonrocks have done that - and each of the 4 of them did it at different times, weird little buggers that they are! I'm a bit puzzled why or how you're seeing signs of pre-flower if these are photoperiods and being grown outdoors... but maybe you're growing somewhere that the nights are getting longer? Still, there's no place on the planet where there is an equinox (12 hours of daylight and 12 hours of night)... so perhaps you're seeing something that isn't really there. Post up a real photo and ask your question again!