Brigadier Andrew Parker Bowles and HLF London committee chairman Wesley Kerr planted a silver birch to commemorate the event today (21 January).
The gardens in Bull's Cross, Enfield, were created by EA Bowles, one of the greatest gardeners of the 19th and 20th centuries. The two-year project will open the Victorian Kitchen Garden for the first time, show how horticulture was carried out in Victorian times and create education and training programmes and restore historically important artefacts.
The story of Bowles, including rarely seen artefacts and historic photographs, will also be made available to visitors at the gardens, owned by Lee Valley Regional Park Authority which uses Bowles' grand house as its head office. Bowles was born at Myddelton House in 1865 and died there in 1954.
Kerr said: "All great gardens carry the imprint and character of their creator. Even though Edward Bowles died half a century ago, the broad outlines and some of the plants from one of London's most poetic horticultural plantations remain at Myddelton House in a remarkably peaceful and evocative setting.
"The potting shed feels as though Bowles had just stepped out. HLF is pleased to help restore this historic and delightful garden, which will soon be open to the public for no charge. It's a great addition to the £95 million we have already invested in London's parks and gardens and, together with the investment nearby at the historic mansion Forty Hall, will help make north Enfield, already a gardener's haven, a fine heritage destination."
The grant will greatly enhance the information available to visitors about the garden's creator, plantsman EA Bowles, who is recognised as an outstanding gardener as well as a writer and talented botanical illustrator.
The gardens contain the national collection of the bearded Iris, plus a wealth of other plants as well as wildlife. Bowles was a prolific plant breeder and more than 40 varieties named after him are still available in the RHS catalogue.
Bryan Hewitt, Bowles' biographer and senior gardener at Myddelton House said:
"This award means a renaissance for Myddelton House Gardens. I have worked in the garden for 25 years and it was all but derelict and forgotten until Lee Valley Regional Park Authority began a restoration programme in 1984. We have recently received a Green Flag Award for the garden and now we can create a visitor centre dedicated to EA Bowles.
"We will be restoring historically significant monuments such as the Enfield Market Cross and other garden ornaments cherished by Mr Bowles. The Victorian Kitchen Garden will once again be up and running and the long-neglected boiler room that Mr Bowles' father used to heat his glass houses from 1859 will be restored for use as a potting shed."
The Heritage Lottery Fund has made 60 awards to projects in the London Borough of Enfield, totalling £5,223,665. Its most recent award, announced in October, was £167,500 for the development planning of a project to restore nearby Forty Hall.