Yellow roses have turned to red

Sounds like reversion - assuming the growth of the rose itself wasn't any different from before, just the flower colour. The breeders bring out new hybrids, and a lot of them do not stay "true" and revert back to one of their ancestor's colours. Though red from an originally yellow rose is the wildest reversion I've heard of - usually it's things like peach turning pink, white turning pink, pink turning white, etc.

It's cos it rains in Wales a lot...the poor thing has succumbed to acid rain! :0)

pH of the soil may be a contributing factor. But it could also be due to a mineral imbalance.

It is probably a grafted rose. The rootstock will have been from a red rose.....possibly Dr. Huey.....and the yellow HT will have been grafted to it. What has happened is the rose has been killed down to the roots.....that means the grafted part of the rose (the yellow) has died and the rootstock has sent up shoots of its own. Dr Huey is a commonly used rootstock and has red flowers.

I suspect the root stock is to blame...Thanks for all your comments...will pass on to my friend

I had a yellow Romantica in the ground for 20 years, the last few without care.
It is now a bright red.

Since my Toulouse Lautrec was a hybrid, it makes sense that the root stock may have become dominant after the romantica died.

I'm so happy to find a reasonable exclamations, as well as another yellow to red story!!

Thank you!

Sharon
California