Sturgeon's focus will be on making the modern garden during his workshop on 11 February, while Giubbilei plans to explore the boundaries between architecture and art on 29 April.
Also lined up to present talks during the series are John Brookes MBE, Great Dixter head gardener Fergus Garrett and OCGD principal Duncan Heather, who will discuss garden photography.
Brookes will give a masterclass on 11 March, Heather will speak on 13 May and Garrett on 16 June.
All of the classes will be held at St Hugh's College, University of Oxford, and cost £20 — classes are free for OCGD graduates.
For further details, visit www.garden-design-courses.co.uk.