Breaking ground for the lectures at Kew, it will be filmed by consumer magazine Gardens Illustrated and made available as a podcast.
The event is being organised by students taking the Kew Diploma in Horticulture. They are running the debate to raise money towards their final-year field trip to study the flora of southern Spain.
The evening will be hosted by Noel Kingsbury and Professor Denis Murphy.
The panel includes National Botanic Garden of Wales director Kevin Lamb; director Dr Peter Wyse-Jackson of the National Botanic Gardens, Glasnevin, Dublin; Royal Botanic Garden Edinburgh regius keeper and director Professor Stephen Blackmore; and Kew director Professor Stephen Hopper.
Audience members need to submit questions to the panel prior to the event. To submit a question, email email@example.com.
The event will be held at the botanic garden's Jodrell Lecture Theatre, Kew Road, on 18 February.
Tickets are £10 and can be reserved via the email address above or on 020 8332 5545.