They are competing in the amenity section of a wider national contest, organised by Recreation Aotearoa and sponsored by Farmlands.
The Recreation Aotearoa Young Amenity Horticulturist of the Year competition was being held at the garden for the first time.
It involves a host of activities, from pruning, and using machinery, to identifying plant diseases, and tackling quizzes.
The young horticulturists are tested on their practical abilities, business skills and horticultural knowledge.
Dunedin Botanic Garden team leader Alan Matchett said it was a "privilege'' to host the two-day national event, and early on the first day some contestants were "pretty nervous'' about the demanding event.
"They'll know they've been in a competition,'' he added.
"This is a great competition to challenge young horticulturists who have already started their journey in this field,'' Mr Matchett said yesterday.
The competition will be judged by garden staff and external horticulturists.
The winner will be announced at an event being held at Larnach Castle today, and the winning young horticulturist will later compete in the overall Young Horticulturist of the Year final in Auckland in November.
