repeat-blooming from new dawn seedlings

referring to another thread where it was asked if new dawn gives remontant offspring, the answer is yes, if the pollen parent is. Various places I’ve mentioned how great my mini(flora) Silver Sunrise is. A sterile, hardy very floriferous offspring of Rise N shine on ND. I have lots of other examples with both mini and HT pollen donors. Problem is to carry through the disease resistance, true yellow color and floriferousness all at once. But a majority bloom at 6 weeks; the rest go out to the compost pile. I could give exact #s, and will do so one day when I write it all up.

Dr. W. Van Fleet gives no repeat-blooming offspring in open pollination, I think ND gives some, but I tested that many years ago. But mildew is dreadful on selfs of these for some reason.

I think I may have written in the RHA newsletter in the late 80s regarding ND. I think the repeat bloom is because the new canes are determinate, which is to say, they end in a bunch of flowers. By contrast Dr. W. van Fleet produces only indeterminate new growth, every shoot of summer is going to grow until water stress or short days, shuts it down.

Most repeat-blooming HTs on the other hand have about 7 leaves per lateral shoot according to Netherlands scientists who studied that in greenhouse grown roses. I’m too lazy to look up the ref, but I think DeVries was one author. Basal breaks may be determinate like ND with a longer cane below the flowers. So in some sense there are two main kinds of reblooming. The third kind is what I’ve seen with Harison’s yellow where there may be late-breaking lower buds if one cuts back the flowering canes to make bouquets. I’ve also noted that those late flowers are often more like Austrian copper with red in the top surface of the petals, presumably as a function of heat.

And our local wild rose will rebloom until August if you take off the hips. I found it blooming in October where road crews mowed it regularly in the country. That was from new wood determinate “basal” canes.