Don't forget that some
plants require themselves to be potbound in order to
flower. For example: Bird of Paradice, Jade, Ivy, etc.
It is a good idea sometimes to change the soil though. When i got my ficus, i immediately went outside and tried to clean all the soil off of the roots. Since it was bought at shaws, it was full of alllllllllll kinds of bugs; silvafish, centapides, milipides, a cicada, spiders, fungus gnats, spider mites, etc. >.< I don't recommend buying from a grocery store... Stupidest thing i've ever done with
plants.
I did get everything cleared out though. But ya, whatcha can also do is make your own potting mixes. I find it cheeper than buying a bag of miracle gro, or scotts all the time. Plus your
plants will probably grow better, because the mix you gave it isn't a generic brand for all
plants. Its made especially for that
plant