To elaborate and more specifically, most strains "stretch" to between 2 and 3 times their height within the first 21-24 days of flowering. All strains I've grown less Jack Herer nearly triple.
When cannabis plants go into a flowering stage they like to get specific n-p-k nutrients added to them to uh how shall we say encourage sexy flowers! Lots of info at this site that can turn your head in the right direction!Pics always help the gardeners here discern and awensers you may need or insight. I love cannabis!