A masterplan statement sent to Lake District National Park planners by Shaw & Jagger Architects in August seeks permission for reinstating the historic gardens as well as a replacement cafe, new pool, outbuildings and relocated glasshouses.
Plans include reinstating the kitchen gardens that were Potter's inspiration for Mr McGregor's garden in Victorian children's story The Tale of Peter Rabbit. Potter stayed in the house for nine summer holidays.
The 14.4ha Lingholm Estate, on the banks of Derwentwater in Cumbria, was sold to the Seymour family by the Kemp family in 2013. The grade II listed Victorian hall was designed by Natural History Museum architect Alfred Waterhouse.
Shaw & Jagger architect Alison Mudd said: "The plan is to completely reinstate the garden that used to be on the estate, with an octagonal garden based on the original that Beatrix Potter knew." There would be three full-time and two part-time gardeners.
The masterplan statement says the principle reason the estate has fallen into neglect is that it has failed to provide enough income for maintenance. Expanding the current holiday letting business and reopening the cafe would generate £756,000 a year.
The Seymours said: "We are committed to making a significant investment over the next two years to restore the infrastructure to the buildings and grounds."
The grounds and house have not been well-maintained over the past three decades, according to the statement. The grounds have not been open to the public since the early 1990s.