Last year, I had the opportunity to visit inside the FMC, Rochester, MN, which is a part of the Bureau of Prisons, Department of Justice, housing federal offenders with mental health needs. This is a document about job opportunities at the FMC, which features a section on the horticulture program: http://www.bop.gov/jobs/students/cpdiprch2.pdf.
While I was there, I was impressed at how beautiful the grounds were. Even in winter, the manicured lawns and clearly cherished trees looked like a college campus, at the least. While touring the facility, I had an opportunity to observe several different sessions of treatment that combined therapy and skill-building for life after release. I didn't talk to any of the individuals involved in the horticulture program, because they were totally uninterruptable. They were sitting in a greenhouse attachment (it was March, and fairly inclement weather), discussing a book with a new technique in it, talking about whether or not they wanted to try growing that kind of plant this year. There was a therapist present, although the gardener seemed to be the one facilitating that particular discussion.
I later spoke with the therapist, and she told me that there was a lot of controversy over the program. Apparently, the program walked a fine line of violating laws about using prisoners as a workforce. Because they could grow food in the garden, it was considered slave labor, as prisoners are not supposed to be forced to farm, a law dating back to prison reform earlier in the 20th century. And yet, with this tension, it was hard to justify the program as therapeutic, and not forced labor. Finally, it was passed through as a job skill-building program, so that offenders would have a chance at employment once released, however, the therapist confided that the program did the most good as a therapeutic tool in an unconventional population. Going forward, I would be curious to attempt to quantify the benefits that she told me about, in order to begin to grapple with the policy implications of horticulture therapy as an aspect of life at the FMC. I immediately had the urge to "prove" that the program was beneficial to the population in such a way that it would be above the challenges to its legality, legitimized as therapy to the point where it wouldn't be confused with illegal labor.