Archives For green roof

Gardeners and farmers know that healthy plants need good soil and the right amounts of both water and sunlight. But green roofs are intentionally built with an engineered soil-like substance that more closely resembles a pile of rocks than rich, moist potting soil.

To make matters worse, the tops of buildings are often blindingly sunny and very hot in the summer. So how do plants like grasses and wildflowers survive in this type of harsh environment?

PHOTO: Cactus and allium grown on green roof.

Cactus and other succulents retain water in their tissues. Ornamental onion (Allium) species have underground bulbs that help them get through cold winters and dry summers.

Not all plants will grow on a green roof, even in the temperate Midwest. Most plant species that are successful in the desert-like habitats of green roofs have beneficial adaptations that allow them to absorb and store water and nutrients. Some have succulent leaves with thick waxy coatings to prevent water from evaporating. Others have roots that grow horizontally rather than vertically to maximize the areas from which they absorb water and nutrients. Some use a modified type of photosynthesis to prevent water loss during the hottest and driest part of the day. Still others use bulbs or underground tubers to store nutrients during the long cold winters. Some species may even form partnerships with special fungi in the soil that help their roots with more effective absorption.

While plant species evolved to develop these various adaptations on the ground, such traits serve the individual plants very well in the harsh environment of a green roof. The next time you visit a green roof, you might see a striking diversity of species but you won’t see any wimps. No, these plants are both beautiful and tough. 

PHOTO: Shortgrass prairie plants grown on a rooftop garden at shallow depths.

Even in very shallow soil and full sun, some plants that normally grow in shortgrass prairies are able to grow and reproduce. (This is from some of my research at Loyola University.)

PHOTO: PCSC green roof in summer 2015.

Plants can be both tough and beautiful on green roofs. (This photo is of the Plant Science Center last summer.)

Find more of the best plants for green roofs on our Pinterest board, and see Richard Hawke’s Plant Evaluation Notes for the plants that performed best on our green roof.


Students in the Chicago Botanic Garden and Northwestern University Program in Plant Biology and Conservation were given a challenge: Write a short, clear explanation of a scientific concept that can be easily understood by non-scientists. This post is part of their series.

©2016 Chicago Botanic Garden and my.chicagobotanic.org

We’ve selected the top 9 plants for green roof gardens from our 5-year study of 216 taxa. Download the results of plant evaluation manager Richard Hawke’s extensive study. 

INFOGRAPHIC: Top 10 plants for green roof gardens.

©2015 Chicago Botanic Garden and my.chicagobotanic.org

The Sky’s the Limit

Results (and Surprises) from the Green Roof

Richard Hawke —  July 20, 2015 — Leave a comment

When the Green Roof Garden was first planted in 2009, everything we knew about long-term rooftop gardening was theoretical. Which plants would live more than one year on the roof? No one knew for sure. Were native plants better to plant than non-natives? Unknown. What about soil depth, extreme weather, pests, diseases? The list of questions was long.

Download An Evaluation Study of Plants for Use on Green Roofs here.

PHOTO: The Roof Garden at the Chicago Botanic Garden Plant Conservation Science Center.

Download the results of this 5-year study. Click here.

Today, after five years of watching, waiting, documenting, and evaluating, we now have actual data to guide us—and others—on the ever-more-popular topic of green roofs! I’ve just published the Plant Evaluation Notes from our research—the first national plant evaluation study of its kind.

Among the data are a few surprises.

The biggest surprise may seem the most obvious—it’s that the green roof survived as well as it did!

I was blown away by the survival rates among plants, and by the fact that so many of them thrived and even excelled in such a challenging landscape. Of the more than 40,000 plants that we installed on both roofs, 30,568 of them were still alive in 2014. Just 14% of the 216 taxa died—that’s a pretty good success rate when you consider rooftop conditions. In fact, adaptability was one of the main criteria that we evaluated each plant on. Here’s the five-point list:

  • Adaptability (to hot/cold, dry, windy conditions, plus shallow soils)
  • Pests/diseases
  • Winter hardiness
  • Non-weediness
  • Ornamental beauty

Other surprises? Definitely the wild white indigo (Baptisia alba var. alba). Although I didn’t expect it to fail, I also didn’t expect it to be as large and vigorous as it has become. By year five, it was nearly three feet tall, with dramatic spires of white flowers. Meadow blazing star (Liatris ligulistylis) was in the same elegant category. But the absolute standout was prairie dropseed (Sporobolus heterolepis). It looked good all year, at all soil depths, and the fragrant flowers made the roof smell like popcorn in August and September.

PHOTO: Antennaria dioica.

Antennaria dioica

PHOTO: Baptisia alba var. alba.

Baptisia alba var. alba

PHOTO: Phlox subulata 'Emerald Blue'.

Phlox subulata ‘Emerald Blue’

PHOTO: View of the Green Roof Garden from above.

The Green Roof Garden today: a tapestry of plant life

It also surprised me that some of the drought-tolerant plants like sulfur flower (Eriogonum umbellatum), tufted fleabane (Erigeron caespitosa), and long-petaled lewisia (Lewisia longipetala ‘Little Plum’) didn’t do better on the green roof. Same goes for sundial lupine (Lupinus perennis). In a broader sense, I’m disappointed that we haven’t had greater success with plants in the shallowest, 4-inch soil depth. It’s the most challenging area on the green roof, so we’ll strive to add more types of plants to this trial area in the coming years.

PHOTO: Richard Hawke, Plant Evaluation Manager.

Monitoring plants in the field

Top 10 starstarstarstarstar Performers
on the Green Roof

  1. Pussytoes (Antennaria dioica)
  2. Dwarf calamint (Calamintha nepeta ssp. nepeta)
  3. Juniper ‘Viridis’ (Juniperus chinensis var. sargentii ‘Viridis’)
  4. Creeping phlox ‘Emerald Blue’ (Phlox subulata ‘Emerald Blue’)
  5. Creeping phlox ‘Apple Blossom’ (Phlox subulata ‘Apple Blossom’)
  6. Creeping phlox ‘Snowflake’ (Phlox subulata ‘Snowflake’)
  7. Aromatic sumac ‘Gro-Low’ (Rhus aromatica ‘Gro-Low’)
  8. Prairie dropseed (Sporobolus heterolepis)
  9. Prairie dropseed ‘Tara’ (Sporobolus heterolepis ‘Tara’)
  10. The 69 other plants that got four-star ratings (good)! 

 

What else is coming to the Green Roof Garden?

We’ll bring in a new set of plants (both native and non-native) to be evaluated and increase the replication of trials in 4-, 6- and 8-inch soil depths. Our goal is to compile a broad list of proven plants so that anyone—businesses, architects, governmental groups, and residential homeowners—has the information they need to grow a green roof. The sky’s the limit!

Visit the Green Roof Garden at the Daniel F. and Ada L. Rice Plant Conservation Center—open ‘til 9 p.m. all summer. The garden has two halves: the Ellis Goodman Family Foundation Green Roof Garden South and the Josephine P. & John J. Louis Foundation Green Roof Garden North.


©2015 Chicago Botanic Garden and my.chicagobotanic.org

Do you ever feel like trying to understand plant science research can be as daunting as deciphering a passage written in a foreign language?

As a budding plant scientist in the joint Chicago Botanic Garden/Northwestern University Ph.D. program, I find it exciting to pick through dense scientific text. Uncovering the meaning of a new acronym and learning new vocabulary can be thrilling, especially when decoding something new.

PHOTO: Kelly Ksiazek speaking in Sydney, Australia.

This past fall I spoke to a group of green infrastructure professionals in Sydney about the importance of urban biodiversity.

But the commonly used styles in scientific writing and presentation packed with language used to convey big topics in small spaces can be really off-putting to an audience of non-scientists. Many of us can conjure up a memory of a professor or teacher who seemed to like their subject matter but couldn’t convey the material in an interesting way. All of a sudden, science became boring.

Rather than struggling to learn this “foreign language,” many folks stop paying attention. Lack of scientific literacy, especially as it applies to plants, is a pity. Plants are all around us! They are so valuable to the entire planet. The very applicable field of botany shouldn’t be something that’s only discussed and understood in laboratories or scientific conferences—it should be for everyone.

This idea inspires me to try and bring my current botany research to a wide variety of people.

PHOTO: Ksiazek takes her presentation on the road to Pittsburgh.

I’ve had the chance to speak with many visitors to the Chicago Botanic Garden about my research, and typically bring some of my research supplies, as seen here from a trip to Pittsburgh.

PHOTO: Growing UP in the City: A Book About Green Roofs.

Writing and publishing a children’s book helps bring my research findings to kids all over the world.

For example, I recently realized that there are very few resources available to teach young students about the habitat where I currently collect most of my data: green roofs. While some of the methods I use for data collection and analysis can be quite complex, the motivations behind my work and some of the findings can be broken down into some basic ideas, applicable to students of all ages. So a fellow botanist and I wrote and produced Growing Up in the City: A Book About Green Roofs.

Our children’s activity book teaches youngsters about some of our research findings. The book follows a pair of native bumblebees through a city, where they guide the reader through engaging activities about the structure, environmental benefits, and motivations for building green roofs. At the end, readers even have the opportunity to ask their own research question and carry out a green roof research project of their own.

Interested in your own copy of our book? More information and a free digital download of the book are available at greeningupthecity.com.

PHOTO: Ksiazek presents her work to a girls' middle school.

Talking to 100-plus middle school girls about why it’s cool to be a botanist was a great experience!

The activity book is just one example of ways that plant scientists can engage with a broader audience and make their research findings more accessible. Some of the other activities that my colleagues here at the Chicago Botanic Garden and I have participated in include mentoring undergraduate and high school students, speaking to community organizations, creating lessons for schools and school groups, volunteering for summer programs, and maintaining a presence on the Internet through online mentoring, blogging, websites, and Twitter.

PHOTO: Ksiazek and an undergraduate student identify green roof plants.

Teaching undergraduate students how to identify plants on green roofs is one way of passing on my research knowledge.

PHOTO: Ksiazek discusses her research with a visitor to the PCSC.

My experiments on the green roof at the Plant Science Center are visible to everyone. Come take a look!

Here at the Garden, we scientists also have a unique variety of opportunities to share our science with the thousands of visitors who come to the beautiful Daniel F. and Ada L. Rice Plant Conservation Science Center. If you’ve never been to the Plant Science Center, you should definitely stop by the next time you’re at the Garden. You can see inside the laboratories where the other scientists and I collect some of our data. There are also a lot of interactive displays that aim to demystify plant science research and decode some of the “foreign language” that science speak can be. For a really interactive experience, come visit us on World Environment Day, Saturday, June 6, and talk to scientists directly. Bring your kids, bring your neighbors, and ask a botanist all those burning plant questions you have! We promise to only speak as much “science” as you want.

For more information about my research and science communication efforts, please visit my research blog, Kelly Ksiazek’s Botany in Action, and follow me on Twitter @GreenCityGal.


©2015 Chicago Botanic Garden and my.chicagobotanic.org

Roof to Table

Read about the roof garden at McCormick Place

Gloria Ciaccio —  August 8, 2014 — Leave a comment

 

Stacey Kimmons, Windy city Harvest graduate, works on the rooftop garden at McCormick Place.

Stacey Kimmons, Windy city Harvest graduate, works on the rooftop garden at McCormick Place.

The Windy City Harvest and SAVOR partnership replaced roof garden at McCormick Place in 2013 with vegetables. Farm coordinator Darius Jones estimates the 2014 season will yield 18,000 pounds of produce. Read about this story and other successes in Roof to Table (PDF) from Landscape Architecture Magazine’s August issue.