The work was kick-started in 2009 by a Heritage Lottery Fund award to Stevenage Borough Council. A major part of it centred on a pond that has been drained and cleared of silt and debris.
A rotten wooden embankment has been replaced with concrete panelling to stabilise the pond edge and surrounding footpaths. Oak cladding has been used to cover the concrete for greater aesthetic appeal.
Other work includes the restoration of the Lady and Doves statue, the installation of a bridge for improved access across the pond and anchored floating islands to provide safe nesting areas for water fowl.
Next month construction starts on footpaths, a toilet block and additional lighting. The renovations are due to be completed by the end of April.
A council spokesman said the park was taking shape: "Thanks to the funding from the lottery Parks for People programme, we will be able to preserve the heritage of these important gardens."