We have hardly mentioned rooftop/above-ground gardening since EDN 30, but activity has continued in this area both at ECHO and a few other locations.  Last summer a large garden was grown on the roof of the main prison in St. Petersburg, Russia, and 18 other rooftops there had gardens ranging from small to substantial.  We are exchanging weekly e-mail messages with a group in Moscow that expects to begin work this summer. 

 

I [MLP] recently visited Doug VanHaitsma and his national colleagues in El Salvador to evaluate the potential of urban gardening in a low-income part of San Salvador.  After seeing slides of all the methods mentioned in EDN as well as tire gardens, everyone chose the tire gardens as most relevant for their needs.  I share their enthusiasm.  (The method seems to have been developed or at least promoted by a United Nations project).

 

Portable gardens that can literally go almost anywhere are made from old tires and a small sheet of plastic film (e.g. garbage bag).  The group in El Salvador had fun moving a tire garden to unlikely places for a garden: on a flat rock, on a steep hillside supported on the downhill side with rocks, on the roots under a tree.  If there is danger of theft or damage by chickens and goats, the tire can be placed on top of something, even along the edge of the tin roof of a shanty.  (People often put pieces of iron on this type of roof to keep it from blowing away because there is not enough framing to adequately secure the corrugated roofing, so one or two gardens might not be a problem.)

 

If a vegetable needs full sun in the winter it can be set there, then gradually moved into the shade of a tree as the season approaches when the sun is overhead.  If the garden is on a rooftop, it can be placed on sticks or stones so that air can circulate underneath, keeping the roof surface dry.  If gardeners themselves have to move, they can take their gardens and the improved soil they contain to their new home.  When ECHO staff member Dan Holcombe (see picture) returned from vacation to the church in Mexico City where he had a rooftop tire garden, he found it flourishing--on a different building.  The church moved it to add a second story to the original building.

Construction is simple and elegant.  Lay a tire flat on the ground.  Note that the top rim is a mirror image of the bottom rim.  With a knife or machete, cut off the top rim.  Place a piece of plastic inside the tire on the bottom rim, large enough so that an inch or two of plastic stands up along the walls of the tire.  Now turn the top rim that has been cut off upside down.  It fits like a lock on the bottom rim, holding the plastic firmly in place.

 

Any suitable soil, compost or potting mix can be used to fill the tire.  You will need to judge when/if fertilizer is needed, based on what you use for a medium and how plants are growing.  At ECHO we sometimes place an empty flower pot or a PVC pipe in the center so that we can see how much (if any) water is standing in the bottom and so judge when to water.

We usually incorporate something with a lot of air space into the medium.  This helps extend the growing medium that is usually in short supply, and makes the garden much lighter.  At ECHO we use cola cans with holes cut into the sides so roots can penetrate the can.  In El Salvador coconut husks, which are everywhere, were broken up and incorporated.  In Mexico City, Dan used a layer of alfalfa hay to provide initial aeration plus subsequent nutrients.