The Meadow at Gardens by the Bay could feature a covered seating area that can accommodate about 3,000 people during outdoor performances at the park.
Another idea being explored is an underground carpark in the vicinity and possibly a permanent stage.
These tentative plans were revealed by chief executive Tan Wee Kiat, who was speaking at the Gardens' first anniversary celebrations last night.
The 2ha Meadow, which has enough standing space for 30,000 people, has hosted international acts such as Jennifer Lopez and Aerosmith.
Yesterday, more than 8,000 people milled around the grass lawns of The Meadow for the celebrations, which featured performances by several local artists such as Kit Chan and Taufik Batisah.
Minister for National Development Khaw Boon Wan and Minister for Trade and Industry Lim Hng Kiang were also present at the event.
The Gardens had welcomed its five millionth visitor, Harlynna Rahmat, 17, last Monday.
The student was visiting the park for the first time with her mother and brother when staff approached her with the news.
"My friends told me the Gardens were fun, so I wanted to come and see the Flower Dome and Cloud Forest," she said.
Yesterday, she was given a private guided tour and other gifts including a Samsung mobile phone.
Reflecting on the Gardens' first year of operations, Dr Tan said: "It's meant to be a people's garden. When we designed it, people wanted it to be more colourful than the rest of Singapore, and to be easily accessible."
He added that the five million mark could have been hit earlier if not for the haze, which cut visitorship by about 10 per cent in recent weeks.
About 60 per cent of the Gardens' visitors are locals, while the ratio of locals and foreigners who visit the two domes are about the same.
The Children's Garden, a 1ha play area with water play, slides and tree houses, will be open by December, while a Cactus Garden next to it will open in the first quarter of next year.