I've been admiring John Welsh's guerilla gardening on Instagram for a while. He creates gardens in tree pits on his street in London. The other day, as I waited for the 39 bus on Torrent de l'Olla in Barcelona, I noticed the dirty, sad tree pit in front of me, and I decided to take a picture of it and send it to John, asking if there was any hope for it.

Here's John Welsh's pre-answer to my question on his lovely Rewilding the City blog.

(I translated his article into Catalan—just choose CA at the top of this page to jump to it, or go here.)