LDA Design, one of the chief landscape architects for London's new Olympic Park, has been made a "park guardian" to prepare the vast open space for its post-games life when it reopens in 2014.
Senior partner Neil Mattinson said: "We have been appointed for an ongoing role for an unspecified time, but I expect it will be for around 12 to 18 months."
The firm's first job will be to draw up a study for fencing the north park.
"The park will be bounded by a low fence in a classic style with a modern twist," he said. "All the security fencing will come down, the park will double in size, and parts, such as the hockey areas, will become green spaces. A new cycle circuit will be built."
Recycling and sustainability would be a major theme of the work and part of the security fencing would be transformed into tree planters, he said. LDA Design would also plant up concourse areas around the main stadium.
Mattinson said he was thrilled to attend the opening ceremony, which was "very emotional after four-and-a-half years' work".
He said visitors were amazed at the flowering meadows and the maturity of planting.
"The 2012 gardens are just beginning to show their class and will get better over the next few days," he added.
Mattinson said that perennial planting had grown a couple of feet high and overall the park looked "absolutely superb".
"Maintenance by Willerby Landscapes has been very good," he said.
Park upkeep Staff work around the clock
Willerby Landscapes grounds staff clip miners' lamps on to their helmets so they can see when they water and look after plants throughout the night at the Olympic Park.
According to the London Organising Committee of the Olympic Games (LOCOG), crews undertake midnight shifts to avoid spectators on the site.
A LOCOG representaive said: "Teams were on site yesterday.Lots of apprentices have been called on to help. It's a great advert for British horticulture, pulling out all the stops to ensure perfection."
Willerby's Olympic Park head gardener Des Smith said: "We'll do night-time maintenance, which will be stressful. In the daytime we walk round the landscape but can't work because of health and safety. Instead of a maximum of three to five gardeners, it will increase to 25 to 30 during the games."