The so called “guerrilla gardening movement” is in actuality not one single movement, but really a loose classification of all gardening activities that take place outside of the boundaries of state or private landowners’ express approval.
This can range from planting pollinator friendly seed bombs in abandoned or neglected lots, to grafting full sized apple branches onto ornamental crabapples trees by the roadside, to installing a community garden in a food desert.
Motivations of guerilla gardeners are as varied as the spaces in which they work. Some may simply desire to make an area more beautiful, whereas others use gardening as a form of direct action to make a political statement about land use, property rights, or food insecurity.
The movement is not without its problems. What are almost always good intentions behind the movement sometimes cannot compensate for a lack of horticultural knowledge: planting invasive species in seed bombs, or introducing bacterial and fungal pathogens with improperly cleaned equipment are just a few of the issues. Additionally, infrastructure like roads and buildings can be damaged if the wrong sorts of plants are planted nearby, and there are public health concerns with planting food crops in public or heavily trafficked spaces.
However, all caveats aside, guerilla gardeners with a good background knowledge in horticulture can bring numerous benefits to both their communities and ecosystems, especially in places where populations are underserved by the local government authorities or private landowners, and where the local ecosystem has been neglected or impoverished by development.
Guerilla gardening can bring both aesthetic gains to communities in which it is practiced: raising property values and sometimes providing habitat for creatures like bees and butterflies, who require forage and safe places to live.
Additionally, guerrilla gardening can provide material benefits, empowering communities where healthy, freshly grown produce is rare or expensive.
This disjointed amalgamation of off hours gardeners is reviled by some and praised by others, but should really be evaluated on a case by case basis on the merits of how well they have served the interests of their local communities.