Urban farming is a unique trend. We hear about it a lot, but except for P-Patches and your neighbor’s always-flourshing garden (how do they do that?), it’s rarely seen. There’s a couple of reasons for this. First of all, urban farming isn’t terribly efficient yet, at least not at scale. Second, when it is done, it’s often out of site on under-utilized pieces of our urban landscape, such as roofs. Last night I had the opportunity to take a tour of one of Seattle’s best known and least-seen urban gardens.

The installation is on the roof of Bastille, a restaurant in the hip Ballard neighborhood. The garden was a part of the restaurant’s plans from the get go a choice that served the restaurant’s owners well. It meant that the excess weight from the soil and water on the roof could be dealt with during build out, making any problems with building codes easy to manage, according to Brad Halm, co-founder of Seattle Urban Farm Company, which installed and maintains the restaurant’s garden beds.

Using a Kiddie Pool as a Garden Container.

The chef wanted to be able to serve “hyper-local” produce when possible, Halm told us, and apparently he can. The garden is able to produce crops year round. At first this was because the first beds installed were hand built wooden structures that included electric heating cables in the soil. During the garden’s first winter, Seattle Urban Farm learned that the cables and the heavy-duty covers over the planters were unnecessary. The ambient heat radiating through the roof from inside the restaurant in the winter is enough to keep the plots warm if they’re covered with plastic. Now they use children’s wading pools covered in polyurethane (the covering keeps the plastic of the pools from degrading in the sunlight).

Most of the crops that grow on Bastille’s roof are short season ones such as arugulla, lettuce, tomatoes and beans though I also saw basil, cucumbers and something called eyeball plant which the chefs are apparently going to use to make tinctures for a special drink. Over the winter, spinach, mosh and miner’s lettuce dominate the garden’s crops most of which are in the ground for just 30-45 days. This allows five to six harvests per year per bed! That’s impressive, but it’s also problematic. Rotating so many crops through the same soil with no breaks in between quickly uses up the soil’s nutrients and fertility. This means that Seattle Urban Farm has to add organic compost every time they plant since there’s no time for the beds to rest with a cover crop on top. As an added efficiency, they use compost from Cedar Grove which also turns the restaurant’s food scraps into the compost it ends up using!

Bastille's drip irrigation system waters the garden three times a day in summer.

The plants use a lot of water, but Seattle Urban Farm has a system set up to make sure that as little water as is needed is put on the beds. Instead of soaking their crops with a lot of water from a hose a couple of times a week as you might in your garden, they use a very efficient drip-irrigation system three times a day. Although it waters more often, the slow drip at the plant’s roots means each plant uses all the water it gets.

Bastille’s installation is pretty impressive considering all the work that goes into it (Seattle Urban Farm visits twice a week and the chef’s constantly harvest crops to use in their dishes). It’s also a beautiful example of what could be done on roofs all over cities. Although a garden like this can’t provide a restaurant or a city with all the produce it needs, if every roof in busy urban districts such as Ballard were to be used, we’d all have the opportunity to eat more local produce, with much less energy consumed per crop.