Ingrid, palm trees have a very very limited root system. That's why it's so easy to transplant them.
What I would be more concerned about is whether the water-requirements of the rose would be compatible with the health of the palm.
Many palm trees in California are struggling against a (disease? Fungus? Insect?) that is killing many of the urban palms.

You might want to consult with someone who is knowledgeable about Palm Trees.

Jeri

Jeri, thank you for your advice. If I were to water just the rose and not the palm tree would that prevent overwatering of the palm? Our soil if very porous and just soaks up water immediately, and this spot gets very hot afternoon sun. If necessary, and especially if the palm becomes diseased, I will have it taken out because it was planted in a very unsatisfactory spot, with fronds actually touching the roof of the house. In general I can admire palms elsewhere but they're not my favorite tree by any means.

Regards,

Ingrid

I don't know. But if you're willing to lose the palm, I suppose it doesn't matter all that much. I doubt it would be harmful to the rose.

Jeri

The disease that is killing palms is a pathogen spread by contaminated pruning equipment. Trimming one infected palm gets the disease on the cutting blades and transfers it to the next victim. It is advised to insist that tree trimmers sterilize their equipment before trimming your palms.

Here is a link that might be useful: Palm problems in So California

Hoovb, thank you for the link to the article, which I read. My husband cut off several dead fronds and none of them have discoloration of the rachis, so I believe the palm tree is healthy. Just read an article on the internet of a man who cut his neighbors's palm tree down out of spite (without paying the tree trimmers). It will cost $76,000 to replace the palm and the offender is now in jail. Just another slice of this crazy life....

Ingrid