i know nothing of business, but if you love plants and want to grow them for a living, being a botany major or something similar seems logical.
the only school i can really speak about is mine: rutgers. Im in rutgers SEBS (school of environmental and biological sciences) and i know we have a major called "plant science" and that we are pretty good at the sciences in general; but cant tell you much about the major as i dont know anyone in it (im an animal science major).
another thing to consider is biotechnology. a lot of plants are produced in vitro nowadays, and there are various needs to know how to produce strains of plants resistant to X or Y. this could easily be applied to orchids, say orchids who dont rot so easy (i never kept one alive over a month).
and of course the business aspect if you want to run your own nursery. however, you could also partner with a businessman down the road for that instead of being a sole proprietor.
so i would recommend a plant science major, economics/accounting/etc. minor, and a few useful biotech classes.
though what you study in school can end up being totally unrelated to your final career. it happens to tons of people and its sometimes a good thing.
Eheim Pimp #296
Canon Pimp #67