well, that's a little hard to answer, as there is no "between", but I'd say that the trees are in gaps in the sidewalk closest to the curb -- there are no buildings there, as they're in front of the community garden itself (I guessed at the street address), so it's pretty much city sidewalk. does Wash West "own" the community garden, or just oversee it?

I feel like these trees have been dead since they were planted, maybe 5ish years ago...

Here is South Strreet Headhouse District (SSHD) response on the two trees:

The two dead trees will be removed and we will be planting only one replacement in November. The new parking kiosk is too close to the other location and makes it ineligible for the tree tenders program.

Dave