Cristopher, your detailed set of pics of the various growing stages of pegging down couldn't be more descriptive!
I suppose @LolaTasmania
, that Cristopher has provided the best explanation far superior to any that I could provide! I have only just one year of a bent/arching cane. As soon as Scepter'd Isle puts out its next flush I'll post pics of it. By growing horizontally canes instead of vertically, the tip dominance dissappears and all lateral buds become flower bearing, so the outcome is a much more floriferous bush. This is the same principle as applied to espaliering ( both fruit trees or climbing roses). However this simply happens much nearer to the ground and just needs a peg driven inside the soil so one can tie the long cane onto it while still pliable. This conclusion is what I arrived to when I just missed a long upward thrusting cane and it got nipped off in a windstorm ( very frequent here). By growing it low, canes are much less prone to breaking off in a storm, no need for extra stakes and plus the bonus of multiple flower clusters instead of a single one at the tip of the cane. I even prune off the last node next to the tip to induce all the lower ones to bloom.
I have at present 32 different D.A's growing here. Not all shrubs send out these basal long canes. Many are naturally much better behaved and new basal breaks stay within the shape of an upright or rounded bush. An example of the latter would be 'Noble Anthony' or 'Mary Rose'. They would be unsuitable for pegging down.
Christopher, you are suggesting that Golden Celebration could be another candidate for pegging down. Do you have others ( perhaps Molyneux, The Pilgrim, Crown Princess Margharetta) ?
My garden keeps changing every season, and this one is no exception. @vaporvac
many of my bushes tend to do what they "really" want and grow into unexpected shapes. Please do post some of your pics, because it widens our growing choices. So if necessary I only end up by lifting and moving them around to a better placing.
Its that part of understanding better how to grow these shrub roses.
Actually, I would love to hear about OGR grown similarly. I have a 'Mme Pierre Oger' bush that possibly would show off its blooms much better if grown thus rather than as an upright bush.
Thanks all for your input!