Soil sulpher will reliably acidify. I use it on my blueberries, japanese maples, and hydrangeas.

Don't overdo it though! A little bit constantly is the way to go, not a whole lot at once.

My RdV didn't seem to care if the soil was acid or not, but others can advise better on that point.

Don't bother too much with soil ph if the rose is growing and leafs are healthy. Just below neutral phBest of Luck :-)

The Original Poster seems to be in SoCal, so there's a strong possibility that her conditions ARE alkaline.

However, if the plant is young, I wouldn't RACE to ammend the environment, 'til you need to.

Then, as Hoov said, a little soil sulfur will be enough to correct. I put a small handful where the emitters will run water over it, and that lasts for a year or more.

When RdV starts feeling chlorotic, she'll let you know.
I have seen her foliage turn ivory white here, in my VERY alkaline environment.

Jeri

The leaves seem ok - it's the flowers that look a bit deformed (probably not because of soil conditions.) I'm just trying to create optimal conditions for this rose. RD has 2 major canes both of which are completely naked of leaves and flowesr except for the tops. I intertwined the twiggy laterals that have leafed out and flowered but she does not look too great...

I think your rose is only just starting to mature.

But, FWIW, many HPs DO have "bare bottoms," with the foliage and blooms above that.
If you can pull those canes over toward the horizontal, you may get blooming breaks all along it.

As far as the bloom form, your problem may in part be this WHACKY weather we're having. I gather we have drizzle forcast for tonight/tomorrow, and then more 50 mph winds due on Weds. Oh JOY.

Jeri

Bought potting soil should not be alcaline, usually slightly acidic. Unless you have added something that would change ph noticeably you container soil should be all right. Containers are a bit more fuzzy than for those who are in the ground, but liquid organic fertilizers are often ideal. For the types of hybrid perpetuals that send out loong straight canes I have started cutting the tip of the canes when the new shoots have developed three-four set of leaves to promote a more bushy growth. When the shoots are new and short they respond very quickly to this treatment.

If you still have trouble with growth you could try a fully soluble fertilizer with all micro nutrients, the sort that dissolve completely like sugar. If this gives much better growth and flowering there is someting hibiting uptake of nutrients.

Yes, the weather has been somewhat bizarre. I'll blame it on the weather and not my inexperience with hybrid perpetuals!

Everything is vertical in my small space and I was planning to train rdv upwards untill it hit a horizontal trellis rather high up. I could conceal her major (naked) canes with laterals I guess until she reaches the lattice. Before I got all this advice, I impulsively added coffee grounds, and then cold coffee to the container. :~0

this post is interesting to me because I have a band RvV... it looks 'ok' but the leaves are a bit yellowy-green and it doesn't seem to be growing as well as some of my other bands...? I'm in SoCal with an alkaline clay soil... should I wait to amend like you were saying...?

Aimee -- Pot your little baby band up to a one-G. That might be enough to make it happy for a while, because the potting soil you use will be more acidic.
When it starts looking chlorotic, you can give it just a pinch of soil sulfur.
You will probably have to do this from time to time in its life-span, because your soil and water are probably as alkaline as mine.

Jeri

Thanks Jeri, how long should I leave the band in the 1 gall pot...?