Well, annihilating a civilization of aphids that are infesting the local circus tent might not seem powerful...but you'll at least get to use a really cool pressurized hose to do it. And you should maybe try belting out an evil laugh, like a comic strip villain, while you do it.
Really though, there's not much power in the retail nursery business. Maybe, just maybe, you'll have a limited ability to help customers select trees for their gardens—trees that might remain in those gardens for many, many years to come.
Maybe you'll even get to help select plants for a larger project, like lining a main city boulevard with trees and shrubs. Is that power? It's up to you—but we don't think you should be hoping for much.