According to Tangible Memories, Californians and their gardens, 1800-1950, it is.
There is no mention of this nursery in the California Nurserymen and the Plant Industry, however.
The Bancroft libary has the catalog and I went to visit it. This is not a photograph of that catalog, because I signed something saying I wouldn't publish it. This is actually an image that I created using fonts that were simlar to the catalog. So many fonts! It must have been more fun to set them all.
- California landscape history books from cglhs
- The Trees of Golden Gate Park and San Francisco includes Warren and Son's in People and Places.
- Tangible Memories mentions Warren and Son's
- The oldest nursery, however, may be A.P. Smith of Sacramento. He had in 1857 twelve thousand rose plants of 200 varieties. (California Nurserymen and the Plant Industry)