Crawley Borough Council bought the land in 1963. The Friends of Worth Park and the council started working together on a bid for Heritage Lottery Fund money in 2007 to restore the gardens, securing £2.42m.
The five-year restoration project led by landscape architect Allen Scott is now underway. Council contractor Land & Water has started work on the lake and turf in the meadow has been removed to prevent damage.
Specialist contractor Cathedral Works Organisation is restoring the Pulhamite stonework on the park's fountain and sundial as well as cleaning the Dutch gardens and Italian terraces.
The landscaping of the ornamental garden is due to start this month and will continue for a year, with a head gardener and apprentices to be appointed in the New Year.