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Expand view Topic review: Rebloom

Re: Rebloom

by Karl K » Thu Jan 17, 2019 4:32 pm

Another form of rebloom is what I have been calling repeat bloom. It occurs when the flower forming habit is imposed on buds, and even on branches, that are not ordinarily expected to bloom. I observed this on what I believe to be 'Paul's Scarlet Climber' that bloomed in four or five flushes in a year, but always on the laterals (or "spurs") that had already bloomed. The following year, more blooms appeared on the same laterals.

Much the same thing happens in some annuals, as Roberts (1948) discussed, that "do not revert to a vegetative growth cycle in a reversed environment, once they have come to flower and fruit."
After-Affect:—Another phenomenon which varies with the flowering habit of the species is the difference in reaction to a change in environment, after the plant has come to flower. Plants with a terminal flowering habit as Klondyke cosmos, poinsettia, Rudbeckia laciniata, Salvia (var. Harbinger), stock (Christmas Pink) and Maryland Mammoth tobacco can be readily changed to a vegetative state after they have come to flower by placing them in an environment which inhibits flowering, plants with a systemic flower forming habit as morning glory (var. Heavenly Blue), petunia (forcing), soybean (var. Biloxi), and Xanthium echinatum do not revert to a vegetative growth cycle in a reversed environment, once they have come to flower and fruit.

The continued flowering of an induced plant after being transferred to an environment unfavorable to flowering (provided it is of a species having a systemic blossoming habit) presents an interesting problem. The mechanism of the "after-affect” has been the subject of considerable theorizing. A possibility of an effective mechanism is presented by the fact that annual plants which show after-affects do not characteristically renew cambial activity once it has ceased at the time of induction and flowering (34). In this connection it must be kept in mind that plants which require a long period of treatment to establish a permanent after-affect will revert to a vegetative type and regenerate cambial activity if the induction treatment is discontinued before induction is completed. Terminally flowering varieties regenerate cambium whenever returned to an environment unfavorable to blossom induction. ... l1948.html
Repeat bloom, rather than everbloom, is also seen on some climbing roses. ... s1939.html

Re: Rebloom

by Karl K » Sun Dec 30, 2018 7:09 pm

AquaEyes wrote:
Fri Dec 07, 2018 10:05 pm
1) ... Similarly, 'Champney's Pink Cluster' has a long bloom because the repeat-blooming 'Old Blush' parent didn't suppress initiation of bloom later in the season, as is typical for R. moschata.
I have pictures of Rosa moschata flowering happily into October. ... chata.html
For many years, people thought that the once-blooming Rosa brunonii was the Musk Rose parent to the Champneyana roses. It was not.
The influence of the real R. moschata can be seen most clearly in the Tea-Noisettes. Each flower is borne on a very short lateral stem, rather than than at the end of every cane or shoot, as in the Teas and Chinas.
This is actually a dominant trait, as we learn from a few descendants of 'Marechal Niel', such as 'Souv. de Pierre Notting' that are bushy Teas with none of the Noisette climbing habit.
Interestingly, the triploid Wichurana Ramblers derived from the other parent being a tetraploid Bourbon, Hybrid Perpetual, or Hybrid Tea don't seem to as commonly (based on what I read) present some later blooms.
There is another possibility that I call "Elective Expression", though it has picked up a few other names in the past couple of centuries. It is known that, sometimes, it is not always a matter of dominance when two alleles are brought together. It has been observed in corn (maize) that when two inbred lines are crossed in the same way, year after, the results are not always the same for a given locus. That is, the maternal allele is suppressed some years, the paternal allele silenced in others, and in still other years both alleles are expressed.

Most of these cases involved are hidden from sight, though they are still important. But the same principle has been observed many times over the years. For instance, when the Trifoliate orange (Poncirus trifoliata) is crossed with the common orange, some offspring are trifoliate, some are unifoliate, and some try to take an intermediate position. Hybrids of the Trifoliate orange with the lemon are even weirder. ... e1911.html

It is useful to consider that the pattern of silencing/expression that was establish in the seedling, is sometimes altered, especially when the plant is forced into embryogenesis, as occurs when an adventitious shoot emerges from a root. This may explain how the reblooming 'New Dawn' came up as a root-sport of the once-blooming 'Dr. W. Van Fleet'. ... wdawn.html
3) I think some species are easier to "nudge" into reblooming than others.
No doubt about it. Way back in 1825, Sarah Mackie listed the 'Scotch Perpetual'. No description, sadly, but at least we do have 'Doorenbos Selection'. However, I think the Damasks have the advantage.

I tried to learn when the "Autumn Damask" first came into existence. Eventually I ran into a wall: older writers were concerned with the medical virtues of plants, rather than with their gardening uses. Lobel and Pena (1571) wrote that garden roses are "also surprisingly fruitful, often twice-bearing, sometimes you may see thrice-flowering." No named varieties.

Ferrari (1633) mentioned only a Rosa "Italica flore pleno perpetua".

Then, in England, Austen (1657) wrote, "As for Rose-trees, some damask Roses, and some Provosts beare a second time, the same yeare, though but few, if cut soone after the first bearing in the full Moone. But besides there is a Rose-tree, called the Monthly Rose, which beares Roses untill the coldness of the winter stop it, about November.

I don't know how to dig further into this, but I will venture to guess that someone plucked hips, and was pleased to observe that some of the bushes opened another crop of flowers. Suckers and cuttings of these favored bushed will preserve the slight tendency to rebloom. And some of the seedlings from these plants may show the tendency more strongly.

And by the way, there was not just one "Autumn Damask". Loddiges (1820) listed the following:
71 portland
103 four seasons
165 blush monthly
264 red monthly 
276 bifera carnea 
280 white monthly 
569 pestana 
617 perpetuelle rouge vif 
660 tout les mois coeur gris

There was also a 'Striped Monthly' at the time, but Loddiges didn't mention it.

Re: Rebloom

by roseseek » Sat Dec 29, 2018 11:34 am

Wonderfully conveniently, the nearest Wunderground Weather Station is exactly next door to me. ... 7279999998 The next ten days, night temps are to range between 32 and 47 F while day temps are between 60 and 66 F. I actually is pretty wonderful! Believe it or not, the fields around us are still supplying strawberries, blue berries and black berries and the fields are already producing cut gladiolus flowers as well as the traditional kale, lettuce, broccoli, cabbage and Brussels Sprouts. The artichokes have finished and been replaced with the "cooler crops". We pretty much always have cool nights. A "hot night" is one which remains above the low to mid sixties.

Re: Rebloom

by david zlesak » Sat Dec 29, 2018 11:00 am

It sounds wonderful Kim! Hmmm. I studied Easter lilies for my doctorate and aspects of flowering was a part of my thesis. Temperatures below 70F can be perceived as chilling to Easter lilies, even though if the temperatures are below 50F the chilling hours (high 30's best) can speed along the chilling requirement significantly. If lilies are below 70F at times and the days are long, Easter lilies can eventually flower. If temps are above 70F they seem to not flower. 70F is a critical temperature. What are your night temperatures? I wonder if consistent chilling being perceived, especially at night, lead to greater flowering and perhaps suppression of RoKSN. Perhaps the stray fall bloom in some roses in other areas is due in part to cooler temps at night starting.

Re: Rebloom

by roseseek » Fri Dec 28, 2018 11:20 pm

We usually don't get "summer heat" until very late, late September to sometimes as late as early November. Much of the California coast is like that. When I worked in Pacific Palisades, we had budded, canned plants of Harkness' Nigel Hawthorne, the Hulthemia hybrid, which flowered from March through October. Many "once flowering" types simply do it. Banksiae and Fortuniana are almost all "summer" flowering. Those on the freeway here in town are still flowering! We usually get about 700 chill hours annually, so we can grow a wide variety of things and "spring" starts early and often lasts until nearly late September. We may have some heat spikes from August forward, but it often drops back into the coastal cool weather. Our "average temperature" is 75 F. That's a HUGE reason I live here!

Re: Rebloom

by david zlesak » Fri Dec 28, 2018 9:48 pm

Hi Kim! That's fascinating!! I wonder what environmental cues are allowing for the reliable rebloom. What an amazing climate you live in!

Re: Rebloom

by roseseek » Fri Dec 28, 2018 12:44 pm

David wrote, "It is interesting to do expression studies in a climate like Kim's in CA where some roses that are once blooming elsewhere bloom again after a summer stress with heat and drought. " Most don't require the heat/drought episode to "repeat", David. Here, they just rebloom as if it is "normal". It's QUITE neat!

Re: Rebloom

by david zlesak » Fri Dec 28, 2018 11:47 am

Here is a link to a pdf from a talk Fabrice and his group put together on this work. ... oucher.pdf

Re: Rebloom

by david zlesak » Wed Dec 26, 2018 6:08 pm

Dr. Fabrice Foucher and his team have done a lot of great work understanding flowering in roses and also associated species like strawberries. Here is a link to one of their papers ... 11.04776.x

There is a key general gene found in many plants called Terminal Flowering Locus (TFL) that basically suppresses flowering, except during specific times of the year and situations when the gene's expression is very low- like our one time blooming roses in early spring. The gene after flower initiation again is normally expressed and flowering is inhibited (producing messenger RNA and ultimately a product that suppresses flower initiation).

There are segments of DNA that move around the genome called transposons (trans=across; poson=position). Barbara McClintock described this first in Indian corn and the flecking on the kernels and she later on a Nobel Peace prize. Transposons are found in animals and other life forms too. They can land and become inserted in a functional gene and mess it up. That is basically what has been described as happening in our reblooming roses and their TFL gene (called RoKSN in this paper to commemorate previous understanding). The messed up version of the gene is recessive and does not produce viable messenger RNA. If the rose is recessive for all copies of this gene containing the transposon DNA within it, inhibition of flowering from the TFL gene is not happening and the rose reblooms (CF= continuously flowering is the term in their paper). It is like this rose is perpetually in early spring without this gene expressing to stop flowering. Once Flowering (OF) is the wild type version of the gene that flowers just seasonally as described in their paper. Transposons periodically can transpose or move. This can be very rare, or sometimes in some other examples, in certain tissues and growth and development stages, occur frequently. Likely, this transposon in the TFL gene doesn't jump out of the gene very often. For striped roses, it seems like there is a transposon in a pigment gene (anthocyanin gene) and it is triggered to jump out in some petal cells at a certain stage of development. Cells continue to divide after that point to make the rest of the petal tissue. The cells and tissue that continue to divide from a cell with the transposon still in place produce no to very little anthocyanin pigment, and the cells and tissue where it jumped out once again produce anthocyanin and those cells and tissue look pink/red/purple. A transposon landing in a pigment gene in corn kernels is how Dr. McClintock first identified transposons.

Sometimes in continuously flowering roses we get climbing sports. The transposon gets cut out and the gene functions again relatively normally in terms of its suppression of flowering and the rose grows long canes throughout the growing season after the initial bloom. Sometimes though, the excision of that DNA segment of the transposon is not complete and it leaves some portion of itself (long terminal repeat). This little bit of material left in the gene can lead to the gene actually being expressed it seems, but to a lesser degree with lesser inhibition of flowering. Climbing Peace from this paper falls into this category.

I suspect this key gene plays the major role in flowering of our roses and the variations we see. The range of variation in flowering may be due to the variations of the alleles of this gene and how this gene interacts with environmental conditions and for alleles that can be expressed to produce messenger RNA, when the expression is reduced to promote flowering. It would be interesting to sequence the variations of this gene there are in some of the roses we may be interested in understanding more about in terms of their flowering behavior. Fabrice's team has done this to some extent. They learned that they can find differences in where a transposon landed/its sequence in 'Old Blush' versus rugosas versus repeat flowering R. multiflora (I assume what led to the multiflora based polyanthas). It seems evident from their research that transposons landing in this key gene occurred in multiple rose species over time leading to the repeat blooming variants. There isn't necessarily one event that led to the recessive repeat bloom variation and all other species and cultivars that repeat are descended from it. That seems to be the story shared in some older rose literature that all repeat bloomers somehow descend from Rosa chinensis spontanea. In nature, however, the trait hasn't been favorable generally and for the most part seems to have not become the norm. It seems though for Rosa rugosa it has taken hold across the species. They do ripen hips relatively fast though and can make it work to their advantage it seems. I'd love to see what can be learned by sequencing this gene in the more reblooming versions of R. arkansana. It would be interesting to do some expression studies of this gene too at different times of the year in different climates to see what patterns/triggers can be identified. It is interesting to do expression studies in a climate like Kim's in CA where some roses that are once blooming elsewhere bloom again after a summer stress with heat and drought.

I've seen/heard about one time blooming variants of both 'The Fairy' and 'Sea Foam' that were unfortunate mistakes. At different liner nurseries (they sell just young rooted cuttings) they kept taking cuttings of the one time bloomers because they made more cuttings (because they weren't blooming). Customers were disappointed their plants didn't rebloom....

Maybe there is something to a dose effect proposed with some of these more intermediate alleles with a portion of the transposon left behind?

Re: Rebloom

by Karl K » Tue Dec 25, 2018 10:02 pm

I wanted to mention this case. I wrote to a friend about it back in 2001, but I can't remember where I read it. Anyone remember it?
Franc Holliger (Canadian amateur rose breeder) crossed the hexaploid Rosa nutkana with a diploid China rose. One of the tetraploid offspring rebloomed, and was reasonably fertile.

Re: Rebloom

by roseseek » Tue Dec 25, 2018 6:46 pm

Thanks, Larry, and to you and the rest of the "gang", too!

Re: Rebloom

by Larry Davis » Tue Dec 25, 2018 6:26 pm

Points well taken. Longevity is also very temperature dependent among roses that last more than 1 day, in my experience. This is a characteristic that the knockout roses have, perhaps in excess. In our climate Rainbow KO will hold petals until they turn green and brown making some preddy ragged looking bushes at midsummer. Fortunately, crosses to roses that tend to drop too fast usually gives something in between the two, not just all or nothing one way or the other which would be the case for simple inheritance of a strong dominant or recessive trait. Some of the drift roses hang on a bit too long also. Apricot drift and it's yellow mutant do that along the street at the campus. Getting RKO traits into a mix with Soeur Therese + another rose has given me a couple intensely yellow roses that last about 3 days in hot weather and more like 10 days in the cool of autumn. If sufficiently winter hardy this may be a useful way forward but it will take a couple years to confirm that part. Good disease resistance too so far.

On the energy use front, I did some calculations several decades ago looking at Carefree Beauty flower production as amount of biomass. If you compare it to agronomic crops, it is very small. You could argue that for something like RKO, the petals block sunshine from reaching leaves and reduce photosynthesis. I don't really buy that argument either. Even if you throw in the total dry weight of hips produced by a highly fertile rose like CB, it is very small compared to soybeans or wheat where the harvest index is around 50 %, and in the tons per acre range for a cold or short growing season. Of course perennials are different from annuals with monocarpic senescence. The Land Institute (Salina KS) is aiming for perennials that yield half as much as annuals. So I think we have a very long way to go with roses, and it's all driven by hormones, and perhaps the time taken for differentiation of one kind of tissue to another. RKO is pretty good at making very short flower stems so it may be going in the right direction.

We ought to be able to get something that lasts like zinnia or marigold, though maybe the composite flower is a cheat. But consider petunias or dwarf snapdragons for flower production or longevity and see where the arithmetic comes out

Merry Christmas. And good breeding in the new year.

Re: Rebloom

by jbergeson » Tue Dec 25, 2018 6:59 am

I know I've said this before, but it's still kind of a new revelation to me. (in response the last paragraph of the previous post)

If a rose's blossoms last two days instead of one, it needs to produce only half the number of blossoms to have the same amount of color on the plant at any given time. If the blossoms last three days, then it only needs to have 1/3 the blooms. It seems like this petal longevity would take less additional energy to produce than actually making new blossoms. Therefore it seems like petal longevity is an important characteristic to breed for, especially for those of us messing with species roses. Once remontancy is regained, blossom longevity will make a vast difference in overall color impact.

Another way to game the system is what Peppermint Pop does...its center petals kind of stick together to make it appear more double than it is. Therefore it can have the bloom power of a single rose while appearing double.

Re: Rebloom

by Rosesbydesign » Mon Dec 24, 2018 1:54 pm

Reblooming in roses is definitely not simple and straight forward. I do not know the science behind it but from observation of seedling and species plants I have seen non-remontant seedlings coming from 2 fully remontant parents ('Gold Medal' seemed to produce a fair amount of non-reblooming seedlings) and more recently from clones of Rosa acicularis that I obtained from my childhood home in Fairbanks, Alaska, I have seen the production of very late (and ugly) blooms on new wood. In the later case, I suspect that the R acicularis clones were confused by our long hot summer and "thought" they had already gone through another winter (they shut down during the summer) and then tried to bloom again in the late summer.

With regard to the variations in "reblooming" seen among remontant roses, there are the "on and off again" rose types with a clear and sometimes prolonged delay between flowering, to the virtually continuous flowering types that bloom all summer long. Among modern roses, one can find the full spectrum between these two extremes. It seems that the remontant type roses that exhibit a profusion of bloom in the spring, tend to be more likely to have clear cycling of blooming times (and later cycles are never as profuse as the spring bloom). The more continuous flowering types seem to have a more modest spring flush, but then continue flowering.

Another component that affects the sheer number of blooms is the actual mass of the flowering - roses with smaller, more lightly petalled roses produce more blooms, while the larger, heavily petalled types produce far fewer blooms. This is a generality though because there are definitely the super performing, floriferous beauties that we all strive to produce. Selecting overall floriferousness as an important trait in parent plants may increase the opportunity to see the real powerhouse flowering machines among our seedlings.

Re: Rebloom

by roseseek » Mon Dec 24, 2018 1:20 am

Thank you for that, Karl. Barney was a gracious gentleman. I had the pleasure of knowing him the last few years of his life. I miss him.

Re: Rebloom

by Karl K » Mon Dec 24, 2018 12:50 am

I happened upon this note just this evening. Thought it might be of interest.

RHA Newsketer 6(2): 5-6 (Summer 1975)
Breeding for Yellow
Bernard C. Gardner, Los Banos, California
"For too long a time I tried using R. Foetida as a pollen parent, in the hope of getting that unfading deep yellow color in a better rose. The seedlings always tuned out to be pale yellow or white. Quite unexpectedly, however, they were continuously flowering."

There are other examples of rebloomers turning up in the F1, including Pernet's. Despite the report that 'Soleil d'Or' was raised from Antoine Ducher x Persian Yellow, some writers have claimed that it must be two generations removed from 'Persian Yellow', possibly helped along by a Hybrid Tea. They present no evidence, but only vaguely mention Mendel.

Re: Rebloom

by Karl K » Sun Dec 09, 2018 6:08 pm

roseseek wrote:
Sat Dec 08, 2018 11:53 pm
Again, climate. Marechal Niel flowers almost year round here. Gloire des Rosomanes literally flowers twelve months of the year right here, and will flower on recently rooted cuttings as well as huge, old plants which receive no pruning. If pruned like a modern, it stops flowering until it has produced the necessary new growth to start it all over again.
'Marechal Niel' seems to needs its wood "ripened" before it can bloom. This behavior has been reported for some other Tea-Noisettes. And so ...
Journal of Horticulture and Cottage Gardener 20: 469 (June 5, 1890)
Maréchal Niel Rose
In the early part of 1884 we did away with one of our vineries (30 feet by 18 feet), and in January, 1885, we planted five Maréchal Niels and one Fortune's Yellow; the former were budded on Briars, the buds being then in a dormant state. That season each bud produced 60 to 80 feet of wood, the result being we cut nearly 700 blooms from them. After they had finished flowering I cut them back to one eye. So well did this system act I have ever since adopted this plan, with such marked results that I shall ever continue it. We have this year cut over 2000 blooms. They are trained and tied to wire 14 inches from the glass; the annual shoots make from 20 to 25 feet, and 3 or 4 inches apart; the size of wood vary from 1 to 2 inches in circumference.
If I'm reading this correctly, the canes had to regrow from the ground (nearly) and ripen before the profusion of blooms arrived. Two thousand blooms on five plants is a pretty impressive accomplishment. And profitable, I'm guessing.

As for 'Gloire des Rosomanes', the oddness of it is that it produces some canes that try to grow tall, while others are shorter and more inclined to bloom sooner rather than later. After the plants get established, it can be virtually impossible (according to Beaton) to maintain them as dwarfs suitable for bedding. And even when he used them for hedges, he whacked the bushes to the ground every other year. That is, odd numbered plants were whacked one year, even numbered plants the next. In this way he had a veritable flower factory.

BTW, the practice of "whacking" may be worth another look.
American Rose Magazine 1(17): 10-12 (Sept-Oct 1935)
To Whack or Not to Whack
It is an acknowledged fact that roses, shrubs, and trees grow more vigorously and develop a greater leaf-surface when pruned. European people are more rose-minded than we are—and grow better roses than most of us—and their pruning is more radical than I recommended in my Manual. Here is an instance that will interest Portland: The most beautiful planting of Mme. Caroline Testout (250 plants) I have ever seen was last summer in a large estate near Bruxelles, Belgium. They were the original plants received from Pernet in 1894, but were pruned to the ground each year so that not even the stubs showed. I dug around one plant; the stool was at least six inches in diameter and the main root-stalk four inches in diameter! Perhaps if that same treatment had been applied at Portland, Caroline would not have petered out! ... k1935.html
House & Garden 55: 90-91, 194, 206, 208 (June 1929)
Last summer it was my good fortune to visit Monsieur Cochet, the fifth generation of the great Cochet dynasty of Rose hybridizers and scientists (Cochet the First helped Empress Josephine in establishing her historical Roserie at Malmaison) at his estate of Coubert, about thirty-five miles west of Paris. He took me around to see great fields of Roses grown for the cut flower market of Paris. In that immediate vicinity are over 750 acres owned by 160 independent owners with a selling organization. They grow Hybrid Perpetuals only, and on August 3rd they were still cutting large quantities of Roses as beautiful and perfect as any grown here under glass — and this had been going on daily since the middle of May.

Walking through those fields, I was surprised to see what I thought to be young maidens (first year growth from buds inserted the previous summer). When I asked one of the owners whether these were new plants, he said to my amazement, "This field was planted by my grandfather thirty years ago and but very few plants had to be replaced." Calling one of the working men, he had him dig around a plant and then I saw a stump several inches in diameter! He explained that each year, in the middle of March, the plants are "mowed" close to the ground; they then grow many new stems three or more feet long ending with splendid flowers; the stems, two eyes below the cuts again sending flower-bearing long stems. I commented on the absence of those long sterile suckers we generally see on Hybrid Perpetuals in midsummer, and my host replied, "The plants are kept too busy blooming to waste their energy on suckers".

This particular field was of Ulrich Brunner. Other varieties doing splendidly and "perpetually" under the same treatment were: American Beauty, Baroness Rothschild, Captain Christy, Duchess of Sutherland, Georg Arends, George Dickson, Gloire de Paris, Mrs. John Laing, Suzanne Marie Rodoconachi, Triomphe de Caen, Vick's Caprice, Victor Verdier. Among the newer ones, Henry Nevard, John Russell, S. M. Gustave V. and Mme. Albert Barbier. I was also told that budded plants only respond to such treatment. ... s1929.html

Re: Rebloom

by roseseek » Sat Dec 08, 2018 11:53 pm

Again, climate. Marechal Niel flowers almost year round here. Gloire des Rosomanes literally flowers twelve months of the year right here, and will flower on recently rooted cuttings as well as huge, old plants which receive no pruning. If pruned like a modern, it stops flowering until it has produced the necessary new growth to start it all over again.

Re: Rebloom

by Karl K » Sat Dec 08, 2018 3:28 pm

Mrs Scott (1939) discussed remontant bloom in climbers. In several of the cases, the later bloom arose from shoots growing out of (or just below) the previous inflorescence. This sort of repeat bloom also occurs in some irises. A second flowering stalk grows up from a vegetative bud below the first stalk. ... s1939.html

Repeat blooming occurs spontaneously in some varieties, but must be forced in others. Penzance found that most of his Sweet Briar hybrids would bloom again if the partially ripened hips from the first flowering were removed. Kim Rupert reports the same phenomenon in 'Schoener's Nutkana'.

Is 'Marechal Niel' everblooming? The reports vary. In one article I read, the plants were forced to bloom once a year, in order to get all the blooms at the same time -- for the cut-flower trade. Otherwise, it seems to mingle everbloom with repeat bloom, something like 'Gloire de Dijon'. However, 'Marechal Niel' has been the parent of some strictly everblooming, bushy varieties that are classified as Teas despite the Noisette ancestry.

There appears to be a lot of Noisette ancestry concealed within the the HT and Floribunda classes. E.g., 'Lady Mary Fitzwilliam' was raised from 'Devoniensis', which was a seedling from 'Smith's Yellow Noisette'. The behavior of some climbing HTs suggests that the repeat blooming habit of the Noisettes is popping up from time to time.

It has too often been assumed that all climbing sports involve gene mutations, but this is not necessarily the case. Here are two notes on the 'Climbing Devoniensis'.
The Journal of Horticulture, Cottage Gardener, and Country Gentleman pp. 152-153 (Feb 21, 1865)
S. J. Pavitt, Rose Cottage, Bathwick, Bath.
In the year 1857 I budded some of the old Devoniensis on the Celine stock, when on the following year many of the plants made shoots from 3 feet to 9 feet in length. I have now in my stock one of the original plants I obtain my buds from, it having withstood the severe winter of 1860-61. ... rigin.html
Journal of Horticulture and Practical Gardening, 9(237): 94 (Aug 1, 1865)
Mr. Rivers states, "... The climbing Devoniensis reverts to its normal condition if buds or cuttings are taken from the blooming shoots." ... sisCl.html
The Brownells' once-blooming 'Copper Glow' sported to the everblooming (?) 'Orange Everglow'. The latter can revert entirely to the former if the more vigorous, once-blooming canes are not cut out.
American Rose Magazine 5(9):185-186 (May-June 1944)
What is an "Everblooming" Climber?
The Brownells,
Little Compton, Rhode Island

While the rose hybridizer cannot successfully combine the true reblooming quality with the ordinary cane-growth of climbers, very satisfactory types may be produced by encouraging the vigorous branching growth of the flowering stems. An illustration of this is the variety Orange Everglow in which these two types of blooming habit are present and segregated. Certain confirmation lies in the fact that if the once-blooming cane-growth is not removed it may by its vigor smother and prevent the establishment of reblooming wood.
'Gloire des Rosomanes' is another one that can't quite decide whether to be short and free-blooming, or tall and less free.
The Cottage Gardener 5: 381-382 (Mar 20, 1851)

Donald Beaton
No one seems to like Gloire de Rosamene for a bed; but by a particular management it makes a splendid bedder, indeed the very richest of all the roses. For bedding, this rose should be treated as a biennial, and no more; that is, to put in cuttings of it every year in April (they will root anywhere, if you stick them firm in the ground), and to plant them in the flower-bed next March, or whenever the bed is ready for them in the spring. Then, from the first of June to the end of August, every shoot which looks very strong, and is likely to run away with the sap, as gardeners say, must be stopped when it is six inches long. In this way all the shoots over a whole bed need not differ much in strength, and they will not stop from flowering in July or August, as this rose is apt to do when older plants are used. After the beds have done flowering in December, the plants must be disposed of, for all the gardeners in the country could not make a regular bed of them the second season, if the soil was ever so poor, and I do not think there is a rose known that will do better in the very poorest soil than this; and it would grow in rotten dung without any soil at all; it is no matter, therefore, for this rose where you plant it as a biennial. On thin sandy soil the plants should stand at six inches apart every way, or even thicker, and nine inches between plant and plant will not be too thick for a good bed of the richest soil, that is on the understanding that the same plants are only to flower one year on the same bed. A border of the old white China, planted round a bed of Gloire de Rosamene, thus managed, is the very best combination of rose colours I know of; and in a mild autumn both will go on flowering down to the end of November, and I have had them in good bud for bouquets in Christmas week. ... s1851.html

Re: Rebloom

by roseseek » Sat Dec 08, 2018 12:30 am

All flowering occurs once the appropriate wood experiences the appropriate heat/cold, light/darkness and can draw upon the necessary water and nutrients. Here, Banksiae and Laevigata "repeat", and in some cases, virtually "flower continuously". And, it is all climate induced. Mine aren't flowering at the moment, but the ones in town along the freeway in full sun with a lot of reflected, radiated heat from the roadway, are flowering themselves silly, now we've had a bit of rain and no real "summer", nor "winter". They spent just a few weeks without any flowers, until we had a rain. Basye's Amphidiploid 86-3 (Banksiae X Laevigata) is beginning to flower in the yard. Teas are also flowering well, while the few "moderns" in the yard are not. Teas don't require the heat levels HTs and floribundas do to flower. Huey will often rebloom here and usually from wood which had previously flowered. The same occurs with my Hugonis hybrids (I no longer have R. Hugonis itself) and Xanthina, while Primula appears to want to "rebloom" from newer shoots. I.X.L and Veilchenblau "repeat" here fairly regularly, even when the "moderns" aren't flowering. The right genes are required, but climate can, and often does, cause them to do what we don't expect.