American Rose Magazine 1(10): 3-5 (July-August 1934)
Rose Understocks
ROLAND G. GAMWELL
Notes of address made at the Annual Meeting

IN THE time allotted to me some observations will be made on the question of understocks, which I am aware has different reactions in different parts of North America. I am wondering whether many of you, when you buy a rose-bush, care to inquire upon what rootstock it was grafted and whether you realize that the rootstock controls in great part the quality of the plant you get.

No time need be wasted in telling you that the lovely hybrid rose of today's garden does not produce the glorious blooms of which it is capable when grown on its own roots, and that, in order to give you the best it has, it must be started out in life with the strong body and generous root-system of a variety which excels in those athletic qualities and which can give to the choicer blossoming plant its own strength and stamina and virile constitution.

This strong-growing variety is known as the understock, and is usually a species rose; that is a rose that is natural or wild in some part of the world. In taking advantage of the virile qualities of these untamed wildings, we look directly to their ability to transmit to the choicer flowering guest-plant their inborn strength and stamina.

The charm of their wild loveliness appeals to the esthetic nature of the rosarian, and, for that reason, species roses are enjoyed in gardens that can accommodate them. Rosa hugonis and Allard's Xanthina give a glorious touch of gold to the shrubbery border; the fleecy snow masses of Japanese Multiflora are extremely artistic; one is irresistibly drawn to the blood-colored Moyesi, the rosy pink of Nutkana and of the well-armed slender Cerasocarpa, while the fragrant Eglantine of the English hedgerows, now happily naturalized in our Pacific Northwest, delights us all with its delicious aroma.

In the choice of an understock other and more prosaic qualities of the species rose are the ones to be considered. While something over 4,000 wild roses are known in the world, less than a dozen are really used as understocks. Just why the number is so few is not known, but the continued use of that few is suspected to be largely a matter of habit. It is natural, too, that a commercial grower should use the kind that is easily obtainable in his own locality.

While there are exceptions, Texas generally uses the tender Odorata, California, Gloire des Rosomanes or Ragged Robin, Oregon, the Manetti, and most eastern states have united on Japanese Multiflora. Up in Washington where rose-growing is a newer industry than in the states mentioned and no understock habits had been formed, there was opportunity for making a choice, there was opportunity for some observation and study. Japanese Multiflora seemed to offer the most advantages, and is now quite universally employed in the state of Washington.

Of the most used species, R. rugosa takes a bud-graft readily and gives flowers of good size and color. But Rugosa has one incurable fault—it throws up suckers from every root-nodule, and one Rugosa plant will make a Rugosa forest of your garden in a very short time.

R. odorata, much used in the South, is too tender in the North. It comes from a warm section of China and, naturally, does not like cold weather. We occasionally have some of that up this way.

Rosa chinensis manetti was once the most popular understock, but its use is now limited, its last real stronghold being the glasshouse, but even there it is losing to Multiflora. Moreover, it produces too many bushes of the grade enjoyed by the department-store trade.

Ragged Robin, or Gloire des Rosomanes, is limited to California growers. It is a good plant in that state and generally does well there. While it is a good understock for a warm country, it needs more protection in the North than hardier species.

Rosa setigera is hardy enough but takes long to develop a root-system and is too hard to bud to be a favorite.

The Sweetbriar, R. rubiginosa, is also hard to bud and too long in making good roots.

Rosa canina is first class, or I might say are first class, for there seems to be a good many varieties of the Dog Rose. Canina is hardy and very vigorous. There are some plants in my garden with trunks as big as your fist and thorns that would almost cut glass. It suckers, too, more than Manetti, but not so badly as Rugosa. Canina takes a bud well and has a fair root-system. British growers swear by it. We don't like it because cuttings do not strike well and the seeds are of slow and uneven germination.

Racial preference, or perhaps it is only habit, makes the Britisher continue to use Canina. He has exclusive confidence in that species regardless of what Canina it is. Just so long as it is called Canina it is satisfactory, although I did get an English rosarian in Vancouver to admit that identical varieties growing side by side were, for some reason which he couldn't understand, doing much better on Multiflora than on Canina.

Canina, however, has one characteristic enjoyed by Multiflora that is valuable or not, depending on one's viewpoint: Both are long-lived. In discussing with a California grower the comparative longevity of Multiflora and Ragged Robin as understocks, the Californian admitted that Ragged Robin was not so long-lived but added that when it died, in three or four years, the good soul that owned it took all the blame for its death, believed she had not given it enough bonemeal or had sprayed with Black-Leaf 40 when lime-sulphur would have been better, and then, undismayed, bought another bush of the same kind, determined to be more generous with bonemeal in the future and reverse the spray formulas. "But," he added, "if she buys a Multiflora budded rose, it lasts forever, the transaction is closed, and all interest in new roses and better roses is blocked in that direction." I have no comment on the logic or merit of the argument. I do, however, believe in progress with roses as with anything else, and so believe in discarding even good ones when similar but better varieties are obtainable. Of course, I am ready to admit while in this city of Portland that the world has not yet been able to produce a better rose than Mme. Caroline Testout.

Rosa nutkana, our best wild rose, has been tried by a number of nurserymen but discarded. Vigorous enough in the wild meadow, when introduced to garden conditions it seems to yearn for the hardships of wild life and pine for companionship of its old friends and neighbors. A few years of civilization is all it can stand. It is short-lived in the garden. R. nutkana was the first rose found by the scientists with Vancouver's expedition in 1792 and got its name from Nootka Sound on the west coast of Vancouver Island, which was Captain Vancouver's headquarters for a time.

A number of other species roses claim support as desirable understocks. During the past ten years discriminating rosarians have been taking interest in the matter of understocks. They have found out that there is a difference in them, particularly in their hardiness, their longevity, and in the quantity of blooms they produce. Some research has been made. Close comparisons have been made. Identical varieties have been budded on a dozen or so of different species. Careful records have been kept, and up to the present time the one species that surpasses all others as an understock is a selected form of Multiflora.

The consistent good behavior of Multiflora justifies the preference so generally expressed for that understock by most of the observant rosarians of the northern and eastern sections of our country. Multiflora seems to be entirely free from disease and shows no susceptibility to mildew or black-spot or to that other trouble about which some easterners raised a hullabaloo four or five years ago, but which proved to be a false alarm. I refer to chlorosis.

Multiflora is free of the suckering habit because, when de-eyed with reasonable care—and it is relatively easy to do a good de-eying job—there is nothing to induce a wild shoot. Multiflora does not throw up stalks from the roots, nor are there any hidden adventitious eyes to give trouble.

Wood-texture differs between rose varieties and also between plants of the same variety propagated under dissimilar conditions. Harder wood is produced by any variety under severe conditions than mild ones. Climatic severity compels the plant to build up resistance through toughening its wood, but when propagated under soft climatic conditions, only varieties that are naturally hard-wooded develop sufficient resistance to endure the burning sun, arid winds, and changeable weather of the greater part of the United States. I hope I may be pardoned for thus suggesting some of the reasons for the superiority of rose bushes propagated in the Pacific Northwest.

It seems to be a plausible statement, and because plausible, readily accepted without proof, that roses have likes and dislikes to the extent that some prefer one stock while others grow better and give better flowers on a different root.

I am not convinced that this is a proved rule, not convinced because no competent record has been brought to my attention. Some solitary instances have been noticed, however. The lovely hybrid Bracteata, Mermaid, hesitates to accept any stock, willingly but with least objection unites with Rugosa. Moyesii, with its gray-anthered, blood-red blooms, also doesn't seem to like an alien root, but grudgingly accepts several. We often hear rose-enthusiasts declare that this or that Hybrid Tea does better on one stock than on another, but persistent questioning discloses merely a theory and not known facts based on carefully recorded experiment.

In a commercial nursery which caters to all classes of rosarians there is not profitable opportunity to have several understocks, and so a rose-grower must seek for and choose that understock which combines the desirable qualities of strong root-system, production of high-quality bush, virile constitution, ability to endure heat and cold, no inherent vices or disease, and one that induces its foster superstructure to approximate the glorious bloom portrayed by the introducer's lavishly worded description.

In my opinion, a strain of Japanese Multiflora carefully chosen after intelligent observation and field-trial—not just any Multiflora, but a selected proved strain—comes nearest to the rosarian's ideal, best serves the ambitious amateur, and is superlatively superior to the Odorata of Texas, the Ragged Robin of California, the Manetti of Oregon, the Rugosa of the Dutchman, and all the Caninas of the British Isles.