Plant viruses can act in different ways. Some are harmless to the plant; others can be quite detrimental. Also, not all variegation is the result of a virus.....sometimes it is just a genetic abnormality or 'sport'.

If your plant appears otherwise healthy and blooms well, I'm not sure I'd be concerned ;-) In fact, I'd try propagating the variegated portions by cuttings. If it remains stable and you are able to consistantly reproduce variegated plants from the cuttings, you may just have "discovered" a new, variegated Annabelle hydrangea!

Thanks so much gardengal - and perfect timing too! I happened to check this for responses just after you posted, and just before heading out for an after-rain walk in the garden. I now have four cuttings in pots, and got to prepare them while listening to baby wrens chirp in the wren house and feel the sunshine after an afternoon of rain.

I know so little about viruses that I didn't want to ignore this as a potential issue if I shouldn't. I also have a lot of Annabelles and Incrediballs.

The plant is very healthy otherwise. And I have to (sheepishly) admit that for some reason I didn't think about cuttings, despite having three other pots of hydrangea cuttings rooting at the moment. So I appreciate the suggestion. I'd thought of separating that part of the plant, but it would be a fall project and I was uncertain about doing it. Cuttings make so much more sense! Thanks again.

I was wondering how the cuttings turned out? I have a variegated dahlia and have been trying to get info about it and read about your variegation.

I've honestly never seen that before. If this were sustainable I'd sure buy one!

Yes, it is quite nice if the whole plant is variegated. I wonder how the variegated areas do regarding sunlight too? Can handle more sun than the regular non-variegated? more sun? Or no change?

Wow - this is an old post, and unfortunately I lost my variegated cuttings. I wish one of my Incrediballs would do that!