I've noticed silica help reduce stretch as well but that's based on my observation and not scientific fact, if anyone has any more info on the matter feel free.
I'm not sure about that....I've been feeding my autos '
Silica Blast' with every feeding (2-3 times a week) starting at around a week (maybe 2) BEFORE she started to flower and didn't notice any 'slow down' in vertical growth....honestly, if anything, she's been going CRAZY with the 'flowering stretch'! I've had to do plenty of super cropping, LST, pruning, etc just to keep my precious 'to-be' main colas from growing into my lights....just my 2 pence