Planting Subway Grates: Step by Step Instruction

The premise of this project is to start a conversation about the potential for plants to filter the air flow from underground networks that exist in our cities. The spaces in between subway tunnels and the sidewalk/street surface can be metaphorically perceived as membranes within our city, and some would argue that they are under-utilized. This particular experiment is situated in New York City.

These are the materials needed for the following how-to guide.

The above images introduce the folding methods needed for creating a burlap circle. 

Take the burlap circle and begin to puncture holes 2 inches into the circle, 2 inches apart. Although we used a zip-tie in this example, a single hole puncher is recommended (see last slide for further details).

Then, take the nylon twine and begin to ‘sew’ through each hole until the entire circle is complete.

Use your hand to hold the base of the circle down while pulling the excess nylon to create a sac.

In preparation for inserting the burlap sac into the subway grate, fold carefully and squeeze through one grate cell until the sac opens up underneath.

Keep a hold of the nylon while pouring soil. Then, squeeze the small plant through, add more soil, and some water. Lastly, tie the nylon to the grate.

Make note that several changes have been incorporated into the procedure for making and inserting this prototype. See next set of images for details.

Preparing the Burlap Sac: After producing several prototypes as depicted in previous slides, we decided to incorporate some changes that would make the burlap sac more efficient and durable.

1. The first change was to create a double fold of burlap around the outer edge by folding 1 inch in, then another. To keep this double fold in place, we used small amounts of glue. Once secured, we proceeded to use a single hole puncher to make holes for the nylon to go through, at 2 inch intervals.

2. We further realized that it might be useful to have a double lining at the base of the sac to retain water more efficiently. We cut small plastic circles and punctured holes to allow some water to permeate.

Securing the Burlap Sac: The initial prototype insertion revealed a setback in securing the prototype for adding the soil and small plant. Rather than allow the burlap sac to simply hang loosely and swing around underneath the grate while attempting to pour soil and insert the plant, we decided to use wire to create hooks that serve to temporarily raise the prototype along it’s nylon twine edge.