Not all plants are suited to the harsh conditions on green roofs. To determine which species would be hardy
against extreme weather conditions, pests,
and diseases, the Chicago Botanic Garden
conducted the largest vegetated roof plant
study in the U.S. Five years of research has
led to the publication of Plant Evaluation
Notes, a report that highlights the best
plants for green roofs in Zone 5.
A diverse group of 216 herbaceous
and woody taxa was evaluated in growing depths from 3 to 8 inches. Nine taxa
received "excellent" ratings for their overall
performance and survivability, including Pussytoes, calamints, Green Sargent
Juniper, three types of phlox (Apple
Blossom, Emerald Blue, and Snowflake), a
fragrant sumac called Gro-Low, and two
varieties of prairie dropseed.
Top-rated plants consistently displayed
good vigor and robust habits, superior
ornamental qualities, disease resistance,
heat and drought tolerance, and winter
hardiness or survivability throughout the
evaluation period. Additionally, 69 taxa
The Best Plants for Green Roofs
received "good" ratings for their strong
“Ultimately, the success of a green
roof is due to the success of the plants
growing on it,” says Richard Hawke,
Plant Evaluation Manager at the Chicago
Botanic Garden. “Plant trials like the one
undertaken here are crucial to increasing
the knowledge about the best plants for
green roof culture.”
The Plant Conservation Science
Center is a 38,000-square-foot, LEED
Gold-rated research laboratory with two
8,000-square-foot gardens on the north
and south sides of the building’s central
clerestory. The Ellis Goodman Family
Foundation Green Roof Garden South fea-
tures regional and national native plants,
many of which are not currently used as
rooftop plants, while the Josephine P.
& John J. Louis Foundation Green Roof
Garden North features a mix of plants
known as good green roof plants, plus
native and exotic plants that have potential for green roof use. Download the full
report at www.chicagobotanic.org.
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RENTALS & SALES
THIS GREEN ROOF at the Chicago Botanic Garden has been the site of a five-year
study to document which plants thrive on top of buildings.