More than 30 species of native reeds, rushes, grasses, sedges, wet wildflowers and irises have been grown initially by Salix in its nursery on the Gower peninsular in Wales.
Around a third were grown from cuttings and seeds collected in and around the Olympic Park before construction started in 2008.
The plants are now being grown-on in waterbeds and pallets in the nursery's Thetford site before they will be planted in the Olympic Park from next spring.
ODA chairman John Armitt said: "The plants growing in Norfolk will help regenerate the Olympic Park waterways to create habitats for wildlife and help 'future proof' the park and surrounding built-up areas against climate change and flooding.
"Wetlands, ponds, swales and widened rivers bristling with plants will help manage flood water and create fantastic new spaces for the public and wildlife."
The Olympic Delivery Authority has been consulting with the London Wetland Centre in Barnes on species selection and planting methods.
Consultation has also taken place with Natural England, the Environment Agency and CABE space.
Subscribe to Horticulture Week for more news, more in-depth features and more technical and market info.