A cluster of vineyards along Redwood Retreat Road, just West of Gilroy, is emerging from obscurity.
Uprooted over 35 years ago, the “Mary Carter Vineyard” was situated on Mt Madonna’s NE slopes (“CS Cushing” parcel on 1929 county landowners map). An old ridgeline road provided access to this planting. During the 1970s and '80s, Grenache and Carignan grapes were sold to David Bruce, Grover Gulch, and Bonny Doon Vineyards.
The Gregory family’s ancient “Vineyard Under the Mountain” is located on Redwood Retreat Road below Mt Madonna County Park. Century-old vines, bearing Zinfandel, Carignan, Petite Sirah, Tokay, and Black Muscat, have been rescued from the hillside’s overgrowth. Bedrock Wine Co., Precedent, and Storrs
currently source old-vine grapes from this reinvigorated site.
A tiny, +130-year-old Carignan block survives near the intersection of Redwood Retreat Rd and Watsonville Rd. It is called “Pamela’s Vineyard”, but formerly was known as the “Rositano Vineyard”. Alfaro Family Vineyards, Martin Ranch / Thérèse Estate, and La Vie Dansante have produced red wines from this vineyard’s fruit.
I am do not believe that Heller Winery’s Carignan is sourced from the “Rositano / Pamela’s Vineyard”.
Redfin website: Photo of “Pamela’s / Rositano Vineyard”

What other old-vine parcels are scattered amidst the area’s young-growth Cabernet Sauvignon, Syrah, Chardonnay, etc? Which wineries source from these vineyards?
1929 McMillan & McMillan Santa Clara Map Detail

Santa Clara Assessor’s Office website:
Property Maps and Records
Parcel Maps of Redwood Retreat’s Old-Vine Sites (PDF Download):
• “Mary Carter” parcel map: APN 756-32-010
• “Under the Mountain Vineyard” parcel map: APN 756-28-007
• “Pamela’s Vineyard” parcel map: APN 756-29-023
Sheet 238: Map of Parcels on Redwood Retreat Road & Mount Madonna (PDF Download)
238.pdf
Several newspaper articles have detailed the history of the area surrounding Mt Madonna, Redwood Retreat, and Little Arthur Creek.
Morgan Hill Life
“Hike with Mike: Robert Louis Stevenson’s Literary Connections to South County”
by Mike Monroe / Robert Airoldi
February 13, 2015
Gilroy Life
“Take a Hike with Mike Monroe: Learn the Wonders of Mt. Madonna”
by Mike Monroe
May 12, 2018
Gilroy Dispatch
“The Story Behind the Stories”
By Martin Cheek
May 20, 2005
Image: “Redwood Retreat, near Gilroy” from VisitGilroy

Google Books
Wineries of Santa Clara Valley
by Bev Stenehjem
Acadia Publishing (2015)
The late Claudia Salewske wrote a couple of books on the history of Gilroy. The oldest of her two books is very difficult to track down, but her contribution to Arcadia Publishing’s history of Gilroy is not:
Google Books
Images of America: Gilroy
by Claudia Salewske
Arcadia Publishing (2003)
Morgan Hill Life
“California Conservation Corps Worked at Mt. Madonna During 1930s”
by Mike Monroe
December 22, 2020
The Living New Deal
“Mt Madonna CCC Camp, Almaden, CA”
James F. Justin Civilian Conservation Corps Museum:
http://www.justinmuseum.com/famjustin/ccchis.html
Google Arts & Culture Blog
“CCC Camp Mt Madonna”
Fernwood Cellars website:
Martin Ranch Winery website:
https://www.martinranchwinery.com/
Bates Ranch / Janaca Vineyards website:
https://www.batesranch.com/
Mt Madonna County Park website:
https://www.sccgov.org/sites/parks/parkfinder/Pages/MtMadonna.aspx