Expert Brian Patrick Flynn was kind enough to share the following tips:

Synthetic grass on a rooftop is the perfect way to evoke a park-like outdoor feeling ten stories up in the heart of downtown. Brands such as NewGrass are self-draining, fade resistant and require no maintenance so you get the look and feel of fresh cut lawn without all the hassle.

Turn your old deck into an area rug! A great way to inexpensively update your old deck is to use a stencil and create a faux area rug directly onto the surface. All you need is a custom stencil and porch and floor paint. After you are finished, the deck will look years newer and the colors will make your area feel more like an outdoor room.

Plants on rooftops have to be able to withstand intense direct sunlight as well as heavy winds. A great alternative to flowers for your rooftop landscaping is grasses. They look pretty as they move with the wind, require less water than most flowers AND they also add more privacy from other rooftops the higher they grow.

Don't have irrigation on your rooftop deck? Consider using eco-friendly rain barrels or cisterns from websites such as therainsaver.com. Once these are installed, they gather the water run-off on the roof via gutters. The water is collected in the cistern then pumped out into a hose so you can water your plants without driving up water bills and use recycled water.