My buddy in Chicago tried to install a small herb garden on his balcony last year. He didn't seal the planters right, and water leaked down to the neighbor below. The landlord freaked out over the repair costs, just like @ben_fisher mentioned. Now my friend has to pay for the drywall fix and lost his security deposit. Makes you wonder if roof gardens are worth the hassle for renters. What do you guys think about balcony gardens instead?
Landlords definitely panic over water leaks, no joke. I had a few potted plants on my old balcony and the drainage messed up, leaving stains on the ceiling below. Got charged for it when I moved out, so balcony gardens can be risky.