How old are your plants ? Sometimes new roses take a while to get thicker canes. I have both of those roses and at year 4 they both have nice thick canes and no nodding.

Almost three years.

It seems like they should be thicker by now.

They look like this. Anything I can do to encourage sturdier growth?

I would try adding potassium fertilizer.

I did add some langbeinite after the first flush but did not see any difference. Maybe it didnt dissolve well as i just sprinkled around the drip line.

Hmmm...I'm the queen of overdoing everything. I'd add more...but then I killed most of my roses last year overdoing everything. So don't listen to me. :)

Own-root or grafted? A three year old own-root is still a young rose, and may simply need more time.

The usual recommendation if the rose is mature, and still has issues is to try pruning it harder. Then the blooms should be produced on shorter, thicker stems.

@mad_gallica (z5 Eastern NY),

I am not sure. I got it potted a couple of years ago from David Austin, I think.

It's probably grafted. I will try a harder pruning next Spring. Thank you!