There are some species and cultivars that bloom on new growth, without chilling or other encouragement. The lumpy “Rosa arkansana” complex is famous for this habit, and in some races (R. alcea Greene) are hardy to -60F. Far removed from these in hardiness, the very old “Rosa indica major” reportedly bloomed on new canes the same year. No report on whether they could be forced a second time, but it also (reportedly) bloomed all winter in mild climates.
Hybrid Perpetuals bloom similarly (some, at least) pushing up new canes with blooms, repeatedly.
It seems to me that crossing HPs of this kind with the Arkansana-types would be a better route to ultra hardy rebloomers for the Great White North and similar climates.
American Rose Annual, 22: 47-48 (1937)
The True Dwarf Prairie Rose
Percy H. Wright
Rosa suffulta Greene, otherwise R. pratincola Greene, grows wild over a large area in the American and Canadian plains. It is, perhaps, one of the most drought-withstanding rose species in the world, occurring even on the driest knolls. It is, therefore, naturally a dwarf rose, sometimes blooming when only two to three inches high. The flowers and seed-hips, however, are not dwarf, but rather larger than those of some of the bush species. I have never observed it over a foot high, even on moist lands.
[Note: Greene described Rosa suffulta as native to the southern Rocky Mountains, nowhere near Wright’s home. The name “pratincola” had already been used for a European species, so Greene renamed the American plant Rosa heliophila.]
In my district, at Wilkie, Saskatchewan, about 250 miles north of the international boundary, it is the only rose growing in the open. As winter temperatures here sometimes sink to -60° Fahr., even without snow-covering, the local strain of it is of the utmost hardiness. R. blanda occurs in the ravines in the same area; on cool, northerly slopes, we find R. acicularis.
The flower of this dwarf denizen of the cold prairies varies from deep pink to white, with occasionally a cream tint in the center. Marvel of marvels, this humblest of roses is everblooming! It will normally bloom and bear seed after the infestation of the snout-beetle is over, and so severe is that pest in dry years that sometimes such late blooms will be the only ones to be spared. I have seen this rose in bloom even at the doors of winter, on roadsides, or elsewhere where cultivation had destroyed the early growth. The everblooming habit of this species is surely evidence that the rose genus is not limited but that the everblooming habit is deeply ingrained in it.
http://bulbnrose.x10.mx/Roses/breeding/Wright/Wright_suffulta2.html
New Phytol. 37: 72-81. 1938
PHYLOGENY AND POLYPLOIDY IN ROSA By EILEEN W. ERLANSON, D.Sc.
R. arkansana is semi-herbaceous and has a dwarf ecotype R. alcea Greene (Erlanson, 1934) which can withstand 60° below zero Fahrenheit in Canada (Wright, 1937). They are all plants of upland habitats as contrasted with the stream-bank and swamp habitats of the more primitive diploid and hexaploid species. The tetraploids come into flower after the related diploid species and usually continue to produce flowers in terminal corymbs on the season’s turions throughout the season. R. acicularis, R. blanda, R. nutkana and R. Woodsii have a strictly limited flowering period of about 2 weeks.
http://bulbnrose.x10.mx/Roses/breeding/Erlanson/ErlansonPhylogeny1938.html
Gardening Illustrated and Rural and Suburban Home, Volume 6: 244 (May 31, 1884)
The China Rose (Rosa Indica) is a strong growing, climbing Rose, with glossy foliage and large bright pink flowers, almost scentless, which open quickly, and fall to pieces as soon as opened; the wood will not stand frost, but if cut down in the autumn it will make rods 4 to 6 feet high in early summer, which flower freely. Its blooming season is too short to make it worth growing. — J.D.
http://bulbnrose.x10.mx/Roses/Rose_Pictures/I/RedouteIndicaMajor.html
House & Garden 55: 90-91, 194, 206, 208 (June 1929)
THE RENAISSANCE OF THE HYBRID PERPETUAL
J. H. NICOLAS
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”.
http://bulbnrose.x10.mx/Roses/breeding/NicolasHPs1929.html