The college, near Chelmsford in Essex, achieved the very lowest score for its horticulture and floristry department after inspectors found that achievement and standards, teaching and learning, as well as guidance, support and management were all inadequate.
The report noted that "planning of horticulture theory lessons only uses a narrow range of teaching and assessment methods that take insufficient account of individual learning needs and fail to involve and challenge students effectively."
A Writtle College representative said the recommendations had been acknowledged and plans were underway to make improvements.
"The college has already taken positive actions to make improvements and a restructuring of the management of the FE departments will ensure students continue to receive the very best teaching and support," she said.
Inspectors also found that although staff are well qualified and have industry experience, course review and self-assessment exercises do not pay sufficient attention to raising the quality of teaching and learning.
A previous visit to the college last year by Ofsted inspector Keith Boulnois highlighted good practice in horticulture and floristry, but noted areas for development included sharing that practice across disciplines.
Lantra national director for England Madge Moore said she would be encouraging strategic partner Landex, an association of colleges with specialist provision in land-based subjects, to look at the quality of provision at Writtle.
"We would look to Landex, and its quality director, to work with colleagues at Writtle to help address the issues raised by Ofsted," she explained.
In addition to appointing a new interim head of further education - Christine Howard, who started on 19 August - the college is about to embark on a £30m project to rebuild parts of the campus.
The planning application for redevelopment of the main campus on Lordship Road is expected to be submitted to Chelmsford Borough Council in the coming weeks.
The proposal will see a number of existing buildings demolished and new facilities added, including a main teaching building, reception building, animal-care building and associated barn, mechanisation workshops, machinery store and caretaker housing.
- Good practical skill development in floristry
- Good practical resources
- Good use of visits and study tours to enhance the curriculum
- Low pass rates on Advanced National Certificate in floristry
- Very low success rates on National Diploma in horticulture and
National Certificate in gardening
- Insufficient planning of theory-teaching in horticulture
- Ineffective target-setting and action-planning
- Insufficiently developed quality assurance procedures