Lee Valley Regional Park Authority (LVRPA), which owns and runs the gardens, won a £487,500 Heritage Lottery Fund (HLF) grant in 2009 to restore areas that had fallen into disrepair. Work on the site - the birthplace of botanist and author Edward Parker Bowles - included renovation of the kitchen garden with its Victorian potting shed and peach house.
Park authority chair Derrick Ashley said: "This has been a fascinating project, uncovering many hidden plants that had previously been lost. Thousands more people will now be able to enjoy these wonderful gardens free of charge."
HLF London committee chair Wesley Kerr said the project would complement the investment in restoring parks and green spaces.