What has your moisture been? As in rain, watering, ect. The leaves don't look dry like it's being underwatered, but I think roses can also suffer from overwatering or sudden onset watering at the wrong time. Or maybe a temprature dip at the wrong time?

I have seen this from time to time and wondered too. I vote for immaturity.

I’m keenly interested in this, as I have several roses that do this and I’m unable to pinpoint the problem. Eustacia Vye does this badly in my garden. This is her third spring here and she is doing better than before, but still dropping many buds. I hope someone has some insight.

Could it be temperature related? You are now gardening in Indiana , right? Down here in relatively balmy east Tennessee, my garden hit 36 F on May 3. (I had a max min thermometer out with my trays of seedlings about to go into our veg garden). Doubtless your temps were colder that that and maybe for several nights?

Beesneeds, we've had an abundance of rain, but that soil is very well drained. Yes, there have been wild swings in temperature. No frost since the buds developed though. Sheila -- I guess it could just be immaturity of the plant, although I've not had that happen on other roses. Stillanntn, yes, Anderson, Indiana. We've had low 80s and mid 30s. Perhaps that's it, but it would surprise me if the lower temp affected an Alba much, and now we're back in 60s-70s days, and 40s-50s nights, so I'd think that would be delightful to an Alba. Thanks everyone for the comments.

I think sometimes, particularly when they are young, once bloomers put out more flowers than they can support. Then they get rid of the excess. It wouldn't bother me unless it becomes a habit, and the rose is a stingy bloomer otherwise.

Agree with Sheila and mad_gallica: the rose may be dropping buds when it has more than it can support. I used to have roses that would do this, and they didn't seem to have particular problems.

Malcolm, have you moved to the north? I didn't know, and am a trifle shocked. I thought you were Mr. Florida! N.b. I don't know that my old home state deserved you, but still, what a loss.

Malcolm, thanks for your answer, and I hope you enjoy a wonderful retirement growing things! Florida's loss is Indiana's gain. I sure do understand your wanting to grow all those temperant climate plants.....lilacs? cherries???

My centifolia variegata did this, this year to all buds (the only time ive seen this), in it’s second year, and I chalked it up to it needs to find it’s final home in the ground. I know the bag (yes, bag) is ripped on its’ top edge and it is literally in the far corner of my garden enclosure, I’d say it is inconsistent water and maybe a smidge of neglect on my part. Good luck with yours!

Update: After dropping a lot of buds, the plant is flowering heavily now. I think previous posters were correct -- it simply had more buds than it could support, so it dumped some.

Congratulations on your flowering roses! Good to know it was all right.