The candidates took part in day courses over nine months through Bournemouth & Poole College, said the company's training manager Leon McGready.
"The sector faces difficult trading conditions and it is important that people have confidence to put forward business ideas," he added.
Some of the newly-qualified team will work at the extended restaurant due to open in Southampton this month, with others heading to the £12m new-build centre near Worthing, due to open next March.
Course tutor Marion Atherton said the students' assignments put into practice the theoretical syllabus and each one had to do a presentation.
Inspiration and insight from travels around the horticultural world