Inchbald School of Design director Andrew Duff said key trends will also include more colour than in previous years.
"The gardens at Chelsea 2009 will undoubtedly be more realistic and almost certainly more creative," said Andrew Duff.
"We will see a reappraisal of British native species. They are not only cheaper to grow; they do not require special planting conditions, nor do they attract the costs of import from Europe."
The garden designer and former landscape architect added that silver birch, hazel and box will be taking centre stage.
"Colour will take its lead from a resurgence of 80s florescence," said Andrew Duff.
"Big, bright and bold flowers such as dahlia and tulip will be shouting from a darker background of architectural foliage. Gone are the minimal species meadow planting of last year and here to stay are plants that provide us with ongoing seasonal interest together with a sense of optimism in these grey times. People will be expecting plants to work for their money."
He predicts that we will be seeing a lot of recycled materials this year to tackle the high costs of hard landscaping.
Previous Inchbald School of Design success stories include Philip Nixon and Marcus Barnett, whose gardens took gold consecutively in 2005 and 2006.
Former student Luciano Giubbilei is designing a garden for Laurent Perrier.