I just learned this term yesterday, watching a new cable TV station Current TV.

They had a clip about a fellow in England doing Guerrilla gardening.
http://www.guerrillagardening.org/

Well, I was surprised! I looked at my husband and said...am I a Guerrilla now?

I've had a garden across the street on the city's property for over 20 years (at my expense and effort). I am now restoring the part that was damaged by the street repaving/sewer replacement last spring/summer.

On the corner 2 houses away, they put up a new fire hydrant and some new stones, so I just obtained permission to pretty that spot up too. For the past 2 weeks I've been waiting for the poison ivy to die back. But so far I've put in perennial sweet peas, corepsis seedlings, ox-eye daisy seedlings, and two
Artemesia silver mound young plants.

These two pics are the portion across the street from our home, in progress with new plantings.
from left to right... one tansy, one yarrow, globe thistle(came back after the damage),
in front left to right are silver mound, upright sedum cuttings,
creeping yellow and red sedums, some daisy, some cuttings of creeping phlox.
Since this first photo, I've put in some seedlings of Pearly everlasting, and black eyed susans. (still pretty small).

Second photo is looking down the 150 ft we are fixing..as the shade increases the plants change.
Near where Oreo is supervising, it changes to snow on the mountain (ground cover) and Chinese lanterns. In the background are wild daylilies, myrtle and some goldenrod, not damaged by the crews. Further down out of sight is sweet woodruff from my yard, and some violets, and more daylilies and myrtle. The daylilies seem to grow anywhere and the myrtle is not fussy. Behind this garden my spring things came back, unaffected...trillium, mayapple, some mertensia, daffs, and some scilla.

3rd picture is of the corner garden before I started. Don't have a progress one yet. Things are still small and don't show up.

Any others here doing Guerrilla work? LOL