GardenSmart :: EPISODES :: 2005 show15
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Show #15

Today we look at roof top gardening. Green roofs are all the rage in cities all around the world. Not only are these gardens in the sky beautiful, they help reduce heat in the city, help keep the air clean, reduce water run off and provide an oasis for wildlife. Today we visit an ambitious roof top garden project on the roof of Chicago City Hall and visit with a resident of Chicago that has created a wonderful oasis on her balcony outside her Chicago condominium.

Carolyn Ulrich is the editor of Chicagoland Gardening magazine. Her magazine has been in operation for about 10 years after deciding that there might be more gardens in the city of Chicago than in all of Mississippi. Chicago is a wonderful gardening city. They have a climate that includes tough winters but that only provides a contrast to Spring and affords something to look forward to. Here they have people gardening on high rises, balconies, little triangular corner gardens, the residents take it upon themselves to plant. Little gardens are popping up everywhere. The Mayor has been instrumental in inspiring people to garden, especially on the roof tops. Carolyn makes a distinction. A roof garden can be plants in a container on a roof, on a garage or on the roof of a high rise. A green roof is actually a multi-layered roof construction with plants on top and is planted primarily for environmental reasons, either for storm water abatement or for environmental reasons, such as reduction of the heat island effect prevalent in large cities. Balconies are great places to start.

We start on the roof of Chicago City Hall. We're visiting today with Sadhu Johnston, the Commissioner for the Department of the Environment for the City of Chicago. This is an amazing garden. In 1999 Mayor Daley went to Europe and saw lots of green roofs. In Germany one needed a variance if a green roof wasn't being established whereas in this country one needed a variance to install a green roof. He came back and decided to try one on City Hall. It really is an outgrowth of the many greening efforts he had initiated all over the city.

There are several benefits to a green roof. The first is beauty, it really is beautiful to look at the high rises and see a garden. It creates more of a soft feel against the hardscapes. The second is they absorb storm water. In the city there are a lot of hard surfaces, roads, roofs, bridges, etc. The water will hit the roof, then pavement, then run into the river or lake. Integrating soft surfaces into the city provides opportunities to have storm water held in the soil. That way the storm water is absorbed for about 48 hours on the roofs, it then trickles out and supports plant life. The Urban heat island is another reason. When you come into a city you'll usually notice the buildup of heat. Rooftops, streets, buildings absorb the heat during the day then slowly let it dissipate at night. In the city you don't get the heat fluctuations you would get in the countryside, for example. Thus, it is often several degrees warmer in the city than the surrounding area. By integrating greenery on the roof the temperature on a black roof can decline from 190 degrees to 80-100 degrees. This makes it more comfortable standing outside and on the street but it also makes it easier to air condition the inside of buildings. As well the green roof will last about 20 years longer than a regular roof. So instead of having to replace a roof in 20 years it will last 40 or 50 years. This allows the city to invest a little more upfront knowing that there will be a payback in the longer term. That is because the UV rays hit the black roof and it deteriorates but with a green roof the rays are hitting the plants and foliage which saves money. Sadhu figures that green rooftops can and will impact the temperature in the city and can impact utility bills. Plus, imagine flying over the city and seeing nothing but green roofs.

We look at the garden and its construction. This green roof is about 20,000 square feet, it takes up the entire roof of City Hall. The garden was installed between 1999 and 2000. There are between 3 and 4 inches of soil throughout the roof even though it looks like it's up 3 or 4 feet in places. In areas it is bermed or thicker, for instance areas where there are trees growing there might be several feet of soil. The soil isn't the type for your backyard. It is a manufactured soil that's light and absorbs storm water. This allows the building to support water rather than soil. Much analysis was undertaken to determine the proper soil, thus weight.

There are about 125 green roofs underway throughout Chicago, these are both publicly and privately owned. With the Mayor's leadership, when there is financial support provided whether to a Target or Home Depot or new residential development, the City asks that they integrate green features into their buildings. These features range from a green roof to recycling construction waste or improving energy efficiency or improving indoor air quality. The roof top gardens are the most visible part of an effort the Mayor has undertaken to green the city's buildings.

Sadhu takes us step by step through the construction of this green roof. It works with the regular insulation of a normal roof. Then add a rubber roof, different systems are available depending on the manufacturer. And like a regular roof the rubber membrane keeps water out, it serves as the main protective function to ensure moisture doesn't penetrate the roof. In this system there is a root barrier to prevent the roots from going down into the rubber membrane, this is comprised of a number of different felt layers for the roots to grab onto. Then on top of that goes the soil. Under the areas that are bermed up there is styrofoam.

There are mostly prairie plants on this rooftop garden. A number of horticulture experts helped in this area. It is normal on a roof to have Sedums, lower lying plants that flower at different times of year. These Sedums flower Summer and Fall. They are the camel of the plant world, they hold a lot of water, they're hardy, a Mediterranean species, and they're strong enough to withstand weeds coming through and withstand droughts. With Sedums an irrigation system isn't needed. Plants on a roof must be able to withstand high winds. This garden is 11 stories up and it gets a lot of wind. The rest of the plants are mostly natives. Some original plants survived, others didn't. Like any garden it's an evolving process. They're trying a Prickly Pear Cactus, it's native to the area and seems to be doing well. That is a great point to remember, if growing plants on a deck or patio or up high, select plants native to your area, plants that can adapt to high winds, drought, etc. This will mean less maintenance and ultimately more joy for the gardener. They have added annuals to supplement the color in the garden. They have tried to create a palate that is pleasing to the eye. Dianthus is an example. The colors range from pinks with white in the center to the reverse. Combined with purples and reds, it is a riot of color. This is the height of the season but the color starts in Spring, lasts through Summer and into the Fall. This garden is designed as one would at home. There are taller plants on the top and the shorter plants down below so you have a nice visual. This area attracts a lot of wildlife. There are Butterflies, Dragonflies and Crickets on this roof. In the summer it's like being in the middle of a farm field. There are birdhouses and bee hives on the roof as well. Bees will travel a five mile radius from the hives to harvest their nectar. Since there is a lake nearby and flowers and flowering trees the nectar is exceptionally sweet and very clear. They harvest the honey, called Rooftop Honey, once a year and through a fundraiser promoted by the Mayor the proceeds from the rooftop honey are donated to a non-profit organization. The bees seem to enjoy the environment and the honey is in demand. This garden has a drip irrigation system which is especially important during the hot summer months. It also has a maintenance staff, a partnership with the non-profit Chicago Christian Industrial League (CCIL). CCIL is made up of ex-offenders and folks that are hard up on their luck. CCIL gives them a place to live and trains them in landscaping type skills. These same folks, paid for their training, maintain the roof and also do a lot of the maintenance of landscape medians, plazas and other green areas down town. On the roof they weed, plant and trim some of the Prairie grasses. They're on the roof a few times a week. Just like other landscaping maintenance there are different levels of maintenance. This is one of the higher maintenance green roofs. This roof has an interesting system for watering. As discussed they attempt to keep storm water out of the storm sewer thus have integrated a number of features into this building to accomplish this. Here they have a system that catches or captures rainwater from some of the higher roofs. It goes into a cistern and that is used for the drip irrigation. This system isn't self sufficient, for example during the past few weeks there has been no rain. During times like this the cistern will run dry and regular water will then be utilized. That is a great tip. If you have any kind of roof, it can be used to collect rainwater, then use it around your landscape. This is especially important in areas where you need to conserve water. This saves water and money.

Thanks Sadhu. You have shown us a beautiful garden 11 stories up, on a roof. It has been an enjoyable learning experience.

This week Nancy Clifton with the Chicago Botanic Garden shows us how to make stepping stones with a leaf print. Use a ready to use concrete mix, a drainage pan for plants that can be found at any plant or hardware store, some hardware cloth or chicken wire and some leaves from your garden. Mix the cement according to its' directions and add the mix to the drainage pan. Fill until almost full, shaking it as you go, making the mix level. Add the hardware cloth about half way through so it's buried in the cement. This adds strength to the stepping stone. Shake the mix so it is flat, then select leaves like Hostas or Oaks that have nice venation or have a heavy print on the bottom. Lay the leaf, top side up on the stepping stone, cover it with plastic and a fine coating of sand. Let it sit for 24 hours, remove the sand, peel off the leaf material and underneath you'll find the imprint of the leaf. Let the stone continue to dry in the pan for 3 to 4 more days and the stone will easily pop out of the pan. After another full week of drying the stepping stones will be ready to use in your garden. This is an easy project, very inexpensive, one bag of cement will produce 8 or 9 stepping stones. You could add names, footprints, even little gems or mementoes.

We next visit the rooftop garden of Bernice. She has a 400 square foot garden on her deck, 11 stories up in downtown Chicago. Bernice had previously lived in the John Hancock building and wanted to be outdoors. When this apartment became available she jumped on it. Originally it had a cement floor, not one plant and one beach chair. She started by putting down cedar flooring and cedar facade around the plants. The furniture is Redwood and stays out all year long. The sculptures also stay out year round. She only brings in the cushions in winter, everything else stays out year round. She calls this a sculpture garden. Many plants are green because she discovered that she loved the sculptures as much as flowers. Therefore a green background is less distracting. Thus she has a sculpture garden in the sky. The Annuals are white and of course won't last the winter. Everything green is Perennial, evergreens and they come back. The reason she has selected white Annuals is because she has learned that deep colors, vibrant in the sunshine, get lost at night. Each of the little white flowers is like a spotlight at night. Bernice does a lot of entertaining. In the summer you come to her house, in the winter she goes to your house. Charlie is impressed with the boxwoods and the Privet used for privacy. White Petunias, New Guinea Impatiens, Creeping Jenny, coming out of pots and Hens and Chicks are in strawberry pots. It is a nice mix of plants and feels very cozy, it makes you feel right at home although hanging up in the sky with tall buildings all around.

Thank you Bernice. You've created an inspirational garden in the sky. Bernice thanks us for visiting and tells us she is proud of her garden and proud of herself. We are too.

We hope that this show has provided some ideas for your home. For example, you might now try to create an extra room in your house by gardening on your deck or patio.


Chicago Botanic Garden

City of Chicago

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