The Keith and Elisabeth Murdoch Trust has confirmed an application has been made to Frankston City Council to rezone almost 30 per cent of the heritage estate for a redevelopment.

About 116 homes would be built on about 15.8 hectares on the eastern and southern edges of the property in Langwarrin.

Cruden Farm has been much loved by generations of Victorians, and was the long-term home of philanthropist Dame Elisabeth Murdoch, mother of media mogul Rupert Murdoch.

Five years before she died in 2012, Dame Elisabeth resolved to set up a trust to protect Cruden Farm for the public into the future.

She said it was her wish "that the gardens and other areas be retained largely in the form in which they are present".

On the surface, the new planning application would contradict those wishes.

But Ian Evans, Dame Elisabeth's long-term adviser and chairman of trustees for the Keith and Elisabeth Murdoch Trust, said Dame Elisabeth had envisaged and planned for the land sale.

He said she planted a row of trees to the south of the house and lake with the belief that the paddocks beyond them may be sold.

"Her intention was voiced to me on more than one occasion that she saw that land as easily sold off," Mr Evans said

Mr Evans said that if approved the land sale would provide the funds to allow the estate to be maintained and opened to the public in perpetuity.

"The absolute motivation is to carry out the wishes of Dame Elisabeth. She left a significant property and capital to allow this property to be available for public recreation," he said.

"While the capital is quite handsome, it's not sufficient to maintain the property in perpetuity."

Today, Cruden Farm is open to the public on select days (during events, limited open days or for booked tours, costing $35 a person).

It is envisaged the money from a land sale would allow the garden to be opened five days a week, including weekends. There would also be a cafe.

Entry to the property would be free, and people would be able to wander about at will, although there would be a charge to access the inner garden.

Julian Heatherich, Victorian director of CBD and metropolitan sales for real estate agency Savills, estimated the rezoned land could be worth $25 million to $30 million.

But the sale faces significant planning hurdles. An application to rezone the land, which is mostly Rural Conservation Zone, would have to be approved by the Frankston City Council and Planning Minister Richard Wynne.

And the subdivision is facing opposition from locals. A change.org petition against the land sale by the Friends of Langwarrin Outdoors and Waterways has more than 1360 signatures. The group is concerned about the habitat link the farm provides.

Elisabeth Murdoch was given Cruden Farm as a wedding gift when in 1928, aged 19, she married newspaper executive Keith Murdoch.

The Murdoch family has maintained ties with the property. Rupert Murdoch and wife Jerry Hall were there as recently as February for a birthday party.

Frankston City Council is yet to make the planning application public.