Sprinkle some crushed sugar on them.
Seriously though, grow the right strain and keep the plants healthy from start to finish under plenty of light. That's all you need to do. This "What bottle of crap can I dump on my plants?" is ridiculous.
Learn how to grow and you'll have all the crystals you need.
This fucking Magic Bottle shit is ridiculous. The term "Grower" should not be used to describe a good portion of people with cannabis plants. Too many don't know shit about the plant and think they can find everything they need in some bottle of overpriced, watered down, additive in a bottle with a cartoon label and cool sounding name.
Flush for a week and add some damn Calmag. It's a wonder drug for plants. Double the dose and you'll have so many crystals and they will be so big that it will look like a cluster of mushrooms growing on your buds. Don't forget to give your plants 72 hours of darkness before you chop and do a crystal dance to send all your energy into trichome production. Pour straight molasses onto your plants. The sugars will go straight to the buds and all that sugary resin will crystalize into a beautiful crystal world just like the Fortress of Solitude.