a tall thornless rose

[Diane Whitehead]

I have had two tall David Austin roses, Generous Gardener and Tea Clipper,  for about ten years. 

Today I noticed an equally tall rose - way over my head - with two thornless unbranched canes that have emerged right against the David Austins.  There are sweetly scented pale pink flowers at the top of each.

Could the David Austins have been grafted onto this for a rootstock?

   

[Vinny 123]

Even on very old roses, the graft can usually be easily seen, so if you can, investigate the base of the plants.
Your uninvited guest seems to be very similar to Generous Gardener except in the number or petals - could it be a sport of the variety? If it is from Generous Gardener, will it persist, as in flowers of that form?

What rootstock is used varies across the world, but as your original plants appear to be climbers, in the UK they would probably be grafted onto Dr. Huey, itself actually a rambler, which has deep red flowers (shrub roses are usually grafted to Rosa laxa stocks, which has simple white flowers). Where David Austin might produce plants for N America, would take some digging, or just ask them direct.

[Diane Whitehead]

Thanks, Vinny.

A sport certainly sounds possible, and I like having no thorns.  I'll grow some seeds from it.

[Vinny 123]

Chop some of it into cuttings - far far quicker and easier than seed and you will get what you see rather than potential for cross-fertilisation with another rose.

If it is a sport from the scion, what you may not get is the growth habit as there would be no influence of the stock, as would be the case for seed also.

[Diane Whitehead]

I'll do both.

When I've grown seeds from my two David Austin roses some of the seedlings have bloomed in just a few months from sowing.

[Vinny 123]

 

[Jeffnz]

Rose breeders do get early flowering of seedlings, based on the first flowering they make decisions on which seedlings to continue with.

[Vinny 123]

I have grown numerous roses from seed but never had flowers until the plants are "a few years old" (in other words, I have never kept actual records), so there is probably some juggling of cultural conditions to get early flowering.

An interesting page from the David Austin website - under glass they get small numbers of blooms amongst the 350,000 seedlings that they produce each year.
An interesting comment about timing, if accurate - hips are harvested in November, "stored in refrigerators over winter", and sown under glass in January - they have very short winters in that part of Shrops.!

https://www.davidaustinroses.co.uk/pages/breeding-programme