xD Sometimes I'll plant some and forget about them. But right before I fought the Elite Four in Platinum, I got a metric ton of mulch and planted Leppa Berries with growth mulch in about 40 spots.
I still have somewhere around 200 of them. I attach them to Pokémon that I trade, if no specific item is requested; I think it's just a nice thing to do. Spread the Leppa Berry love. Definitely the most needed berry in a trainer's pack. (Well, either Leppa Berries or Lum Berries, and I don't have many Lum Berries. I could get more, though.)