A representative said planting will begin this spring to allow two seasons for the plants to establish.
The London Wetland Centre in Barnes has been advising the ODA on species selection, planting methods and protection during establishment. Last week the ODA Planning Committee approved plans for the parklands.
Contractors are now being selected to start creating the 100ha park this spring.
ODA project sponsor for parklands and public realm John Hopkins said: "We have almost finished cleaning the Olympic Park site and this spring we intend to start the process of transforming the area into a new green space for people and wildlife."
Bam Nuttall was appointed last year to manage the delivery of the northern section of parklands and procure packages for the whole of the park, with suppliers due to be appointed in the coming months.
A contract to manage the delivery of the south of the park will be issued at the end of this year.