As I understand it, many of the good MBA programs don't even want to see you until you've had a few years of work life under your belt. You still have time to decide.
As for whether it will help, it depends on what your future intentions are. One thing to note, MBA's are getting to be like lawyers - more than the market needs. You'll need a good pedigree to make good jack. If you're using that knowledge to better your business, I dunno. I don't have an MBA so I can't speak with any authority, but I know I've learned a ton in the field that I'd never learn from schooling.
And I don't think the MBA will impress your customers at all. For that you'll want a hort degree, or a civil engineering degree if you're doing lots of hardscapes.