Roof-wise PlantsPlant Selection.Depending on how much time you have to devote to the maintenance of the garden, plant selection is critical. Drought-tolerant and native plants do best in challenging rooftop conditions. They're able to withstand periods of drought and harsh winds. "Use plants that are hardy to one zone lower than your zone," says Mitchell.
Do you plan on using or viewing the garden in winter? Use plants that have winter interest, such as evergreens, trees that produce fruit or ornamental grasses. (Check out these tips for overwintering containerized plants.)