How to Plant on the Roof to Save Energy

Clean the surface of the roof. Make sure there are no leaks, since water damage can destroy your roof.

Cover the entire surface of the roof with a roof membrane, which acts as a water barrier and helps the roof soil to retain moisture. This membrane can either be applied as a liquid that is painted on or in sheets that are rolled out and fastened in place.

Place a layer of coarse stone gravel around the edge of the roof. This helps to hold the soil in place and to promote proper drainage of the rooftop garden. These stones are often called ballast stones.

Spread a lightweight layer of drainage medium over the main area of the roof, reaching to the edge on all sides. Various materials are available for this. One of the most common is made from crushed shells and weighs much less than gravel.

Cover the drainage medium with a layer of protective fabric that will help hold the lower layers in place. It also provides a stable surface for the planting medium to be spread over.

Cover the protective fabric, up to the ballast stone edging, with a fertile, lightweight growing material. Use a thin layer of soil -- about 2 inches thick -- in many cases. If the soil is very deep it can get extremely heavy when wet. Planting medium made for using on rooftops is a better choice in many cases.

Plant the green roof with the plants you have chosen. Space them according to type of plant, depth of soil and exposure to sun.