Climate changes fears have led to the virtual disappearance of traditional favourite water gardens from the RHS event. This year there were just two.
Enfield-based Anglo Aquarium Plant Company was absent for the first time in many years.
Irish designer Fiann O'Nuallain said: "Hampton Court is renowned for water gardens but I've designed a water garden without water, with the grass making the ripples."
The Send a Cow charity featured ideas from Africa including a drought-resistant "lawn" of African marigolds and fodder plant borders for feeding chickens and a cow.
Southend-on-Sea Borough Council's garden The Water Table used reed bed filtration and drought-tolerant planting including palms, grasses and olives.
The Met Office ran a Climate Change Dome, which explained how the South East will experience temperature rises of up to 3.5 degsC by 2080, with average summer rainfall down five to 20 per cent.