Preparations are under way in Surrey for the opening of a new 40ft-high (12m) glasshouse which covers an area the size of 10 tennis courts.
The glasshouse is surrounded by a 1.3 million gallon lake
The structure, at the Royal Horticultural Society (RHS) garden at Wisley, has taken two years to build following a £7.7m fund-raising appeal.
Planting of large palms and other mature trees began last October and other specimens are now being moved in.
The glasshouse will be opened to the public on 15 June.
The RHS launched the fund-raising campaign to mark its bicentenary in 2004.
The society's director of gardens and estates, Jill Cherry, said: "The glasshouse will provide a stunning horticultural spectacle to inspire visitors of all ages, with opportunities for hands-on learning about the pleasure and benefits of growing plants."
The structure has three planting zones - tropical, dry temperate and moist temperate - which will enable 5,000 plants to be displayed.
It is surrounded by a new lake which acts as a reservoir for the garden, holding more than 1.3 million gallons (6 million litres) of water.
There will also be a learning centre and laboratory.