The thing that bugs us about most nurseries is that they often hire high school kids for the summer. It's great to give the kids jobs and all, but when it comes to offering good gardening advice, which many nursery shoppers need, the kids don't always know best. Not so at Longview Gardens. Everyone there, from the teenagers on up, seems to be a gardening expert. Ask them, say, what would grow best in the cracks of a rock wall, and they'll drop their hoses and lead you all over the nursery's beautiful grounds. On top of that, they offer Saturday classes on everything from herb gardens to fall lawn care. Still, advice alone does not a good nursery make. Longview Gardens is stunningly gorgeous and huge, the kind of place you want to spend all day wandering through. It sits on a farm spread on the southeast edge of the city, with rows and rows of greenhouses surrounded by dense flower gardens to offer ideas for home.