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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