Just answered a PM on the issue, thought I'd post a ditty here.
The Stretch is aggravating for indoor growers. Outdoor growers could care less unless they're trying to come under a 6' tall privacy fence (been there, done that). Here is a link on some of the nutritional issues that play into plants stretching, and will apply to cannabis too. I buy foods from these people. They are of very high quality and their tech staff are too. It behooves a large greenhouse op that is growing annuals to ship to far away destinations to grow and finish plants that are fairly short, stocky and with strong stems. Too much ammonical N and high P foods contribute to The Stretch according to this source, light and temps aside for now.
Plant stretch, what causes it?
http://www.plantexsolutions.com/index00c0.html?id=607
Notice at the bottom of this chart there is "no effect" on certain species, so, your mileage may vary.
http://www.plantexsolutions.com/index792e.html?id=606
Many years ago, and still today, I recommended Jack Peters' Blossom Booster, 10-30-20 to pot growers. It's like Jack designed it for pot - the N source is 50% nitrate, Mg is greatly increased to maintain chlorophyll (and there's a good amount of iron for the same reason too), good hit of K to help harden off the plant and reinforce the flowering response.
http://www.jacksclassic.com/flowering_plant_care.html
Here's a tech sheet of what makes a great food, unlike many products you read about here which are not regulated and don't publish their contents. This is a guaranteed analysis:
http://www.jacksclassic.com/blossom_booster.html
Enjoy,
UB