I'm fairly new to this whole plant lady thing, and I was wondering if there's a certain "height" that plants need to be at within their pots. I have this Petra plant and I repotted it in a nice terracotta pot my dad gave me. Problem is, the plant itself lies about three inches below the top of the pot. Is this a problem? It seems to be doing just fine so far, I've had it for two months and r seems pretty happy.