I vote for gardening techniques, too. I suppose other factors might have SOME effect.
Re: talking to plants - I know people talk to their animals, but what would you say to a plant?
Reminding me of Frank Zappa's song "Call Any Vegetable" from "Freak Out" I think it was:
Call any vegetable
Call it by name
And the vegetable will respond to you
(In a yodeling voice) Rutabaga
Can you tell I have too much time on my hands? LOL
"Call any vegetable, and the chances are good
That the vegetable will respond to you"
As far as playing music to weed? Given the rep, you gotta try Grateful Dead. But I don't subscribe to the belief either. Same with that idea of playing Mozart and Beethoven to developing fetus's. A buddy of mine and his wife tried that. Kid was the worst behaved brat I've ever seen, and grew up joining one of them growling, Goth death metal bands.
Even AFTER reading all that Shelly and Yeats to him through a tube!