What is therapeutic horticulture, and does it work?

You have asked for “a briefing on the objectively assessed benefits of social and therapeutic horticulture, particularly for those faced with mental health problems or are recovering from drug/alcohol abuse.” Please find below stakeholder comment on this issue, followed by information on a House of Lords Committee report that references the use of horticultural therapy, and finally press releases and government-commissioned research that may be of interest.