Many of the so called purple strains only show a light purple tinge. Colder flowering can help increase it. The best purple look and a really good smoke is Paradise seeds Sweet Purple. its cheap, good producer, has a strawberry type smoke with the dominate pheno type and it goes purple immediately into flower. In soil with temps in the 60s it will go a midnight purple and in hydro more of a darker lavender color.Heres a few shots of it as i keep it going year round for about years now...These are hydro grown for soil i would say they go about 10 times darker almost blackberry purple...and do not put ice on them as somebody said above as thats just a stupid comment lol...Temps, strains, growing tech all play but mostly the strain which is breed for its color. The ones you got i usually see like Grand daddy purple has just a hint of purple mixed in but they look bit more grey when dried