It took almost three years getting more than 2,000 trees and palms, and over 100,000 shrubs, into Jewel Changi Airport.
The plants span about 120 species and come from countries including Australia, China, Malaysia, Spain, Thailand and the United States.
Mr Jeremy Yeo, head of user experience at Jewel Changi Airport, said: "When we were choosing the plants... we had to consider different criteria, including aesthetics and their ability to thrive within the complex given its light levels, temperature and humidity conditions.
"Before they were transported to Singapore, many of the trees had to be pruned to fit into containers for sea freight."
Once they arrived in Singapore, the plants were nursed back to health at an off-site nursery and acclimatised to Singapore's tropi-cal weather.
Mr Yeo said: "The procurement of the trees took approximately nine months, and another two years were given for the trees to be nursed locally. This process was critical in ensuring that the plants flourish in the climate within Jewel's indoor environment."
From the beginning, the aim was to mirror Singapore's reputation as a City in a Garden, he said.
"As such, the gardens in Jewel are key features in positioning the development as a strong tourism product and a one-of-its-kind, multi-dimensional destination that will enhance Changi Airport's reputation."
Those entering the complex from the main drop-off point and the linkages from Terminals 1, 2 and 3 will be greeted with themed gateway gardens.
A five-storey forest valley will allow visitors to shop and dine amid an indoor forest.
There are two cobblestone walking trails, each about 160m long, with cascading waterfalls and mist clouds along the way.
One of the two main gardens in the complex is Canopy Park. Located at Jewel's top-most level, the park features themed gardens, such as topiary and petal gardens, and dining outlets.