Need Advice - Flowers or Flowering Plants on Sidewalk

here's some good basic advice: http://www.treesny.com/resources.html?#treetips

sun-loving annuals (e.g., marigolds, impatiens, dahlias, etc.) are a good choice with a new tree. be careful of perennials, because you don't want to end up with something that competes with the young tree for water. you are probably ok with perennials that don't send roots deep, but that is riskier and requires more knowledge. stick with the showy flowers they put out from at hardware stores, and you'll be fine. don't plant them right up next to the tree trunk, as you're more likely to injure roots that way.

new trees need a tremendous amount of water in their first year or two, to encourage deep roots. (otherwise, roots will stay shallow -- where rainwater is -- and tree will likely die v. young.) if at all possible, you'd be doing the tree (and the city) a great boon by giving it 15-20 gallons/week, ideally at a slow pace (very gentle hose, bucket with holes in it, gater bag, etc.).

I'd put up a small garden fence with a mesh top on it if you'd like to keep it puppy-dog-pee free.

And I mean a real looking amount of flowers... not some huge arrangement.