They do indeed. This past week I found three blooms on my Glenn Dale, a once-blooming climber. It finished blooming back in May, and this is the first time in many years any later blooms have appeared. I suspect it's due to all the rain, and the wildly fluctuating temperatures we've had since Spring. Depending on the ancestry of a particular rose, local conditions can cause all kinds of weird reactions. The potential has always been there, but something triggers a reaction. Look up "epigenetics", It's fascinating.

This excerpt is about human epigenetics, but it applies to roses, as well. From Google:

Epigenetics is the study of how behaviors and the environment can cause changes that affect the way your genes work. Unlike genetic changes, epigenetic changes are reversible and do not change your DNA sequence, but they can change how your body reads a DNA sequence.

Belle, Yolande was just thrilled to land at your place; she knew a true rose lover when she saw one.

@fig_insanity Z7b E TN Hi fig! It's so cool that your Glenn Dale repeated. I love it when roses do the unexpected. I was wondering if the move to a warmer, brighter latitude might have shocked Yolande it into some kind of growth/blooming spurt. So epigenetics could be the mechanism through which this sort of thing happens? It is fascinating to think about.

@Ingrid_vc zone 9b, San Diego Co. inland Ingrid, I hope Yolande continues to like it here. It's been so hot, temps in the upper 90s and reaching 100 some days, that I was not expecting much from an old HP/Portland until the weather cooled. Before you commented I thought maybe if it continues to bloom through the heat here, that Yolande might be a possibility for you? It's not super thorny, but it does get very tall.

I have some once blooming roses which have huge Spring flushes, and then quit blooming all together until next year (Veilchenblau is an example). I have others which do not re-bloom on the same growth, but do put out new growth which blooms a bit for months. Example - my several bushes of 'Cl American Beauty' (Wichurana hybrid, 1909). When we moved in here there were 3 bushes of it growing in different parts of the garden with no attention to speak of - a great rose.

Also my late lamented huge bush of banksia lutea used to throw out a few random bloom clusters all summer, but only in certain years.

I understand that all roses are affected differently by the specific weather, soil, etc. where they grow. It is one of the things, IMO, which make them interesting and the source of endless delight.

Jackie

I understand that all roses are affected differently by the specific weather, soil, etc. where they grow. It is one of the things, IMO, which make them interesting and the source of endless delight.

Yes!!

I'm more intrigued than ever by this rose's behavior having read at HMF that a DNA study placed it between R. Gallica Officinalis and Quatre Saisons Blanc Mousseux. I guess that would make it a Portland, and those have not done well for me.