As Fall 2015 on the Texas A&M Green Roof drew to a close, there was still much to accomplish. The Northern Green Wall needed 132 plant pockets filled as well as 100 additional feet of hose. This was easier said … Continue reading
And we also added new nine modules for growing proposed crops. In making the substrate and filling soils in the module, firstly we put a layer of substrate to fill the holes in the modules, and a square blanket was used to cover each modules on the top of substrates. And soils for growing vegetation are put on the top of blankets. The texture of substrate soils is coarse which can contribute to positive drainage within the modules and the texture of topsoil is finer than substrate soil and it is opulent with organic matter and water content.
Then the most interesting part came! The transplanted and seed crops arrived, which included Arugula, Chives, Cilantro, Mint, Shallots and so on. Prof. Merrill helped us arrange the layout of different crop species and we took off the outside plastic packings of transplanted crops, burying the roots under the topsoil. Talking about the most difficult part, I think it is to install the irrigation system. I didn’t participate in that part, but I saw my teammates tried to connect the pipe with water source, cut the pipe according to the dimensions of modules, used nodes to connect pipes with chemical glues. Finally, four irrigation nozzles were set up around the crop modules. The nozzle radius is suitable for the site, but one full-nozzle should be replaced with half-nozzle.
Another type of plants we want to grow is succulent plant. So we also had a discussion about the appropriate species for roof planting and before that we each people had a suggestion list. I proposed 6 succulent plants, and I feel so honored that 4 of them had been chosen for growing on the roof, which include Sedum palmeri, Graptopetalum paraguayense, Opuntia cacanapa ‘Ellisiana’, and Euphorbia resinifera. Many other succulent plants are also proposed, such as Nolina macrocarpa, Hesperaloe parviflora, Sempervivum ‘Carmen’, and Agave colorata x parryi and so on. We spent much time on arranging and distributing them in a well-organized and good visual-effect way. We made the short plants as ground cover distributed around the tall plant in the center. The same species are arranged together forming a group.
My name is Chenni Zhu, a third-year MLA student. On the first day we went up to the roof garden, what we were required to do is to remove invasive weeds and pick up mature fruits of some crops such as tomatoes, shallots in the nine modules on the ground. Then we need to weigh the fruits from crops and record the numbers. And I feel what a pity that most of crops grown on the roof in summer are dead for these one or two months. It may be due to the harsh weather which is too hot and dry without frequent precipitation in Texas.
So on the first day, we almost removed all of the weeds in the nine modules. However, what we saw in the next week surprised us that many weeds had grown up again in the modules due to a rain in that week. Thus, we had to weed them again to ensure there is no chance that these weeds would come up again. I have to say that the invasive weeds are really strong and capable of establishing themselves in prevailing conditions without manual intervention, while we should take more care to crops.
After weeding, we were required to discuss what kinds of crops are capable of living on the roof top and surviving well. A study about “Assessing Crop Viability for Agricultural Production on Extensive Green Roofs” provided us with some statistics about which crops are suitable for growing on the roof in Texas. The evidences showed that the strong survivors (80 %+) include Chives, Cilantro, Parsley, Thyme and Mint among transplants. Moreover, among direct seeded crops, strong survivors include Arugula, Garlic, Kale, and Shallots. On the other hand, every team member was required to provide a list of suitable crops for growing on roof. So based on the study and the information I collected, I think the Arugula, Chives, Cilantro, Mint, Shallots and Thyme are ideal crops surviving on the roof. After that, we discussed the final crop species and basic layout of them according to the visual effect of combination of crops, the different demands on water amount of different crops, and numbers of crops.
Below shows the later situation of some crops we grew on the roof. Most of them are in a good condition.
November’s goals could not be pursued without Succulent Garden weed control. A typical rooftop day sees the class split between weeding, collecting inventory/harvest data, or adjusting the irrigation system. The Vegetable Garden’s rapid growth and lush color presented an image … Continue reading
Participating on the Texas A&M Green Roof as a second year MLA candidate has been an enriching experience, as the project has helped to reinforce lessons learned in last year’s site construction course. The semester’s work began by removing all … Continue reading
Spring is here (well as close as you can get to spring here in Texas) and with it has come a revival of plant and crop life! The mint has come back with a vengeance and some of the other plants that were looking dreary are greener than ever!
Zane and I presented our green roof crop research at Student Research Week the week after Spring Break. It was an awesome and rewarding experience. It gave me experience both in poster making and presenting research to a group of judges, I hope this experience will help me in future research presentations.
Other than Student Research Week, we have continued harvesting and have begun to take down the living walls. There is not too much to report this time, but we will be redesigning the living walls and planting new crops and plants. I will also be looking after the crops over the summer after I get back from a month trip to Costa Rica! I’m looking forward to finishing the semester out!
Three weeks ago we harvested some of the crops that had grown on the plots of dirt on the roof of the building. Many of the spinach and parsley plants had a bountiful harvest and much of what we measured was marketable with little defect or holes in the leaves from insects. After the measurements were recorded the team and I began to record the number of plant species that were still living on the three walls. Most of everything was dead as we think the plants may have received too little irrigation. However, all of the succulent plants on the first wall were surviving, not thriving, but indeed were all alive.
On April 10th the team and I learned what species of plants we were receiving for the living walls such as Mexican Petuna and Japanese sedge. Depending on the cost of the plant, the availability, and the predicition that certain plant species may thrive better than others, we ordered more of certain plants than others. After deciding the quantity of each plant, our next business was to decide how they would be arranged on the wall. For wall 1, we decided to go in an organized pattern for 5 plant species making sure that one of each plant species was placed on each horizontal and vertical row. The resulting pattern was one of diagonal stripes by the time we had completed the placement. For wall 3 we decided to follow the same pattern with a different set of 5 plant species, however, we then randomized by switching the order of the rows and columns to make sure there was a degree of randomness in plant order. Wall 2 has not been decided on yet. In the next month as the plants begin to arrive we will begin planting them based on the diagram constructed and see how they flourish. Questions we will be looking to answer are: Does placement on the living wall correlate to the ability to thrive? How do some species respond to the irrigation system verses others?
Wall 1 in the background and showing the height parsley has reached.
The last month we have seen a lot of our edibles bloom out and flower as well as produce edible fruit/foilage. All the wildflowers and bluebonnets around Texas A&M University campus have blossomed as well during this time period. We have recorded the marketable biomass data of our edibles over the last several weeks. Our colleagues within the greenroof course have presented this data during Student Research Week to judges, students, among anyone who was interested. We have collected the most marketable biomass from Lettuce (Butterhead) the past month. The following is the rank for the amount of marketable biomass collected from the edibles: Lettuce (Butterhead): 2458g, Kale (Beira): 973g, Parsley (Italian Giant): 779g, Parsley (Curley Leaf): 309g, Arugula: 300g, Kale (Tuscano): 300g, Broccoli (Arcadia): 242g, Spinach (Emperor): 168g, Radish (Easter Egg): 122g, Kale (Red Russian): 60g, Cilantro (Chinese): 56g. The last week or so we have continued to keep the modules free from ants and weeds to encourage maximum growth for the edibles. We also have started bringing down the plant material on living wall 1. We will bring down the rest of the plant material on living walls 2 and 3 except for the succulents, strawberries, and any other material that looks alive.
Once the new plant material comes in, we will plant them in the modules and bring down the old plant material. We will be planting warm season edibles.
Indian Blanket has bloomed along with the succulents the last couple of weeks.
The first week of class we began harvesting and weighing vegetables that were growing in modules on the roof. I was surprised at how healthy and plentiful all the vegetables were. There was a variety of crops too, including Italian parsley, cilantro, spinach, and even turnips! It was interesting to notice though how the crops on the ground had done so well; however, the plants on the wall were all dead with an unknown specific cause. It is possible that the plants on the wall could come back after winter but little growth was noticed throughout the weeks even when we trimmed the ends of the plants in order to spur new growth. It could also be due to the restricted space the plants are given as they are seated in small pockets along the roofs walls or due to a lack of or surplus of moisture. We hope that over the semester to identify what the problem is and correct it in order to ensure better and healthier plants that can live year round.
Now the planning remains as to what plants should replace those that are dead. After an excellent presentation by Professor Dvorak, who introduced me to the famous botanist Patrick Blanc, I could visualize what our goal was on the top of the Langford Architecture building. We need to find plants that are evergreens and can live all year round and find crops to grow on the modules that rest on the ground of the roof as opposed to the other plants that grow vertically along the wall in pockets. Some of the edibles I would like to plant in the ground modules are rosemary, tomatoes, bell peppers, basil, and cilantro.
Finally, there is one more side to the project and that is using sensors to track some of the plant’s growth and how they are doing in the given living conditions. Dr. Conlee and his students came and together we programmed sensors that can sit in the soil with plants that will be growing on the wall. Eventually we hope that this data will help the class to make conclusions on the influence of a green roof on albedo levels as well as the amount of long wave and short wave energy that is being transmitted
During the past few weeks we’ve planted a variety of food crops on various aspects of our green roof and wall systems. As such, I wanted use this blog entry to talk a little bit about the role green roofs could play in a system of urban food production, as well as highlight the growing importance of the city as a food producer.
Traditionally, cities have relied on their rural surroundings for their food. Not a lot of space in your typical human city has historically been dedicated to food production. As we come to terms with 21st century realities like climate change, resource limitations, and the urbanization of the global population, it becomes apparent that cities are going to need to produce more of their own food. Shifting food production into the cities will reduce costs associated with transporting, handling, and storing food, and also reduce waste. Reducing food wastage is going to be critical in forging a sustainable society. According to the FAO1, the carbon footprint of food wastage would rank it as the third largest CO2 emitter globally after the US and China, and it consumes an amount of freshwater equivalent to the discharge of the Volga. For the sake of visualization, here’s a picture of the Volga:
The United States is a big contributor to food waste, as the USDA reported that 31 % of the nation’s available food supply went uneaten in 2010, good for a loss of 133 billion pounds of food, $161.6 billion, and 1,249 calories per capita per day2. That’s the equivalent of an original sandwich from Chick-fil-A with a large fries, medium coke, and a side of buttermilk ranch sauce, for everyone in America, every day of the year.
Imagine if we actually ate all the food we ordered in this country
What might a food producing green roof in the city look like, though? Or better yet, what role could a green roof play as a component in a larger system of urban food production? Looking at Brooklyn Grange, a rooftop farm in New York City, we can see the answer to the first question.
The Grange has two farms totaling two and a half acres of space that produce 50,000 lbs. of vegetables each year. This is a good start, but vegetables aren’t enough to feed a city, nor can every roof be converted to an intensive vegetable garden. Thus, to answer the second question, I want to think about other concepts that can complement green roofs in urban agriculture.
One is simply converting existing green, public space to agricultural production. The city of Trier, Germany has undertaken a highly successful experiment in this field, creating what it calls an Edible City. The castle in the center of town is a large public space surrounded by parks, and now much of this park is devoted to producing food free to the public, including vegetables, herbs, and chickens. While there were concerns going in about vandalism and over-use by the public, but these were simply never borne out. People seem to respect this use of public space, and the project has increased in popularity every year. The crops are tended by formerly homeless or long-term unemployed individuals who use the program to develop employment skills and find work, which the majority of program participants had done when we visited. You can see how Trier looks below.
This public production of food could do a lot to reduce food wastage by increasing respect for and awareness of food production in individuals who would normally never think twice about where or how their food is produced.
There are also novel technologies that could be paired with green roofs for food production. Aquaponics is a form of production that grows both produce and fish. While it requires a green house, thus precluding its use in the same structure as a green roof, it produces large quantities of fish and produce with limited inputs. The fish provide fertilizer and carbon dioxide for the plants, while the plants provide nutrients and oxygen for the fish. A green roof built for farming could incorporate similar water recycling mechanisms to reduce the inputs needed. Regardless, aquaponics, vertical gardening, keyhole gardening, green roofs, and other new systems could combine some day to produce a meaningful amount of food within the city.
In addition to farming produce on a green roof, there is no reason why simple extensive systems couldn’t be used to raise livestock. While large animals obviously present challenges, green roofs seem like ideal environments to raise smaller stock like chickens. Lay-hens on such a roof could produce free-range, all natural eggs in the city, and converting rooftops to small scale meat production could lessen our reliance on industrial scale meat production with all of its environmental and ethical concerns. This is probably just the organic chicken farmer in me, but I think it’s possible.
There are, of course, other technologies and forms of production that could complement green roofs means of producing food in cities. Many of these are focused on producing as much food as possible in as little horizontal space as possible, which is obviously an objective of urban agriculture. Where green roofs present a novel opportunity is in converting existing nonfunctional space into productive space. Together, these technologies could reinvent our cities as leading centers of innovative, sustainable food production.
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This month we focused primarily on keeping track of how the various food crops we have planted have done on the roof and wall systems we cultivated. Given that this is an experimental planting, we do not expect every species to be successful. Hopefully we can ascertain which species will be viable for green roof production in the future from this planting. As such, I wanted to share my impressions of how the crops we’ve planted on the green roof and living wall have done thus far as we come to the end of the semester.
We’ll start with the green roof, which I have to say is very successful overall. Many of the transplants survived and look healthy, and most of the seedlings have germinated into promising little sprouts. The transplants include primarily strawberry, mint, parsley, and cilantro varietals. Here, you can see them at planting and today (12/7):
As you can see, there has been substantial growth, and to our excitement it looks like some plants are doing quite well. The best performers are the herbs: parsley, cilantro, thyme, and chives. The strawberries and mint are a different story. While the majority of both crops are still alive, they seem to be struggling and just don’t look as happy as the herbs.
From seed, we planted the green roof with lettuce, kale, arugula, spinach, garlic, radishes, turnips, shallots, and perhaps a couple others. Most of these are doing fairly well, with the exception of the turnips and perhaps radishes. All of the seeds planted have germinated into seedlings in a majority of the modules, as seen in the kale and arugula modules pictured below.
There are some differences between varietals as well, as the Beira Kale we planted has fallen prey to some critter that has no interest in the Red Russian Kale pictured above. There is also variation in health among species and varietals across the modules. This seems due to sun/shade discrepancies resulting from all the walls surrounding the roof. Generally, the more southerly modules look less vibrant than others. Given how early in their life cycle it is for many of these crops, it is too early to determine which will produce the best, but overall I am excited with the results thus far.
The living wall we planted primarily with transplants, with some direct seeding to compare. The species included are strawberry, mint, lettuce, collards, garlic, shallots, and some random ones we had left over. Below you can see a picture of the wall midway through planting. This system is designed so that each plant has its own pouch of soil, which is then inserted into a pocket on the wall. The plants are confined to their pouches, which are watered by dip irrigation. As I see it, this design poses several problems, which is probably why the plants on this wall do not look great today.
First, the pocket system puts a lot of stress on the plants. Since the pockets are directly under one another, and not offset, irrigation from the drip system seldom affects more than the row directly underneath it. I pulled many dry pockets off the wall when we were preparing to plant. Furthermore, the pockets contain a limited amount of soil for the plants to grow in, restricting their capacity for growth. Finally, each pocket has a skirt, and this often interferes with sunlight reaching the plant in the pocket below. I had to pull several plants out from behind the skirt and back into the sun during our species count. Below, you can see an example of a pocket, with the irrigation line and the skirt from the pocket above it.
For now, many of the plants on the wall are still alive, but few are doing great. The mint and strawberries look to be struggling, while it’s hard to tell on the lettuce transplants. Nothing seems to have grown much since being up there. Flaws in the roof system aside, it will be interesting to see how the plants turn out in the spring. Hopefully, we can demonstrate that food can be grown on walls as well as roofs.
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For the first few weeks of the green roof and living wall experiential learning class, we concentrated our efforts on inventorying existing plants on two separate green roof systems. These systems had already been established prior to this semester and our objective was to determine which plants had survived and which ones had not. Each student was given a set of plant lists, which were then used to identify and record the condition of the plants that had originally been planted in each module (nine total for each system). We also began removing any weeds from each module, which were then identified and tallied. This was done so that we could have a better idea as to what types of weeds were invading each plant module and to determine their overall invasiveness and potential threat to the remaining plants.
Once all surviving plants had been accounted for, we began discussing the possibility of placing the best modules under one green roof system. This of course meant that we would have to relocate and replant several modules. Relocating the modules took about two weeks to complete, but once the task was done, we proceeded to remove the plants (if any) from those modules which had been deemed as unsatisfactory, as well as brainstorm ideas for what could be planted in those modules.
Transplant the green roof and living wall
This semester we replanted 9 modular of the green roof and living wall #1 with vegetation and crops aimed at research on vegetation establishment on a modular green roof and living wall in south-central Texas. We took off the succulent, bahia grass, and so forth. After that we planted strawberry, mint and lettuce, etc.
- Green Roof
Fig.1 Replant the green roof with vegetation.
We try Lettuce, Parsley, Cilantro, Mint, Strawberry, Spinach, Mustard, Beets, Cauliflower, Kohlrabi, Radish, Swiss, chard, Onion, Garlic, etc. Mint looks pretty good, but herbs needs more attention after we transplanted on October, 22.
Fig.2 The growth status of transplant vegetation.
- Living wall
We try Mint, Strawberry and Lettuce on the living wall. The vegetation grows very well, we will do plant count next week.
Fig.3 Transplant living wall #1 with lettuce, mint and strawberry.
- Green Roof and Green Wall
Building roofs that covered with plants is green roofs. It can be divided into two major categories, one is intensive green roof, and the other is extensive green roof. The main differences of these two types green roofs are the growth substrate depth and the requirement of the roof structural reinforcement. (Oberndorfer et al., 2007) Our research focuses on the extensive green roofs, whose growth substrate depth less that 20cm and require little maintenance. Plant selection is the main task to build up a sustainable green roof, especially subtropical climates, like south-central Texas, which encounter with drought and heat every year. We need crops that can be water tolerant and unirrigated.
Building wall that covered with vegetation is green wall, which holds a growing medium and soils. It can be categorized according to the type of growth media used: loose media, mat media, and structural media. The planting forms are watt pocket, square pocket and independent pocket(Fig.1).
Fig.1 Three planting forms.
- Crop selection
There are lots of crops can be taken into research, green leafs are creamy green leafy lettuce, arugula, purple cabbage; Spices, Thai basil, sweet basil, parsley, mint, chives; Vegetables are tomatoes, strawberries, cucumbers, broccoli.
As it suggested in the list, the strawberry and mint are the main crops of this research.
- Green roof economic of strawberry
There is a strawberry garden case in Shenzhen, China. Based on the test result, the temperature on the “green roof” is 12 Celsius lower than the surrounding concrete roof, and the average temperature of attic is approximately 4~7 Celsius. The strawberry is evergreen with many leaves. It does not need as much soil as most plants, about 120Kg per square meter. And strawberry likes humidity environment and has strong water absorption ability, which totally satisfies the need of green roof. What is more, a strawberry garden of 7000square feet produces strawberries about 4000 pounds annually. The market price for strawberries is $1.5 per pound, which produces an annual profit of $6000.
- Strawberry Fields Green Roof and Garden
This green roof sits atop an office building in downtown Vancouver. I helped design and build this roof in 2009 as a green oasis for the company employees and a demonstration of green roof technology for other businesses in the area. The roof was dubbed Strawberry Fields because of the abundance of strawberries planted among the sedums.
- Mint (Mentha)
The leaf, fresh or dried, is the culinary source of mint. Fresh mint is usually preferred over dried mint when storage of the mint is not a problem.
Oberndorfer, E., J. Lundholm, B. Bass, R. R. Coffman, H. Doshi, N. Dunnett, S. Gaffin,
- Kohler, K. K. Y. Liu, and B. Rowe. 2007. Green roofs as urban ecosystems:
Ecological structures, functions, and services. BioScience 57: 823-833.
Today, we propagated plants for the green roof so that we could increase the stock of the plants. After those plants grow larger, they can be used to replace dead or missing plants on the green roof/walls, and to begin filling up the new green wall after it is installed.
The new green walls system initially looks like it is going to work very well. There is one central bag in each module, which is filled up with soil. Then, slits will be cut into it where each plant is put in. The outside of the module is a harder plastic material that can be cut for larger plants or left alone for smaller plants. It seems that with this module we won’t have many issues holding the plants and soil in place. I am unsure of the irrigation type we will use for this new system, so that will be interesting to see. I think the most effective will probably be if we put a few sources of water through each module, rather than just one or one source at each plant; this is because the soil and plants are all held contained in one area, but if we put only one source in each of the modules, the water would probably not drip all the way down to reach the lower plants.