I am not surprised, Zuzu. The species for hulthemias grows naturally in a more arid climate than yours and I am guessing your soil is not sufficiently alkaline for the plants to thrive. They are not drought tolerant, but they do have soil preferences.
You already know that an unhappy rose is more prone to disease. That's one of the reasons I've never bothered to grow any of these roses because I knew that with my heavy rain season and that my soil isn't right, I felt the plants would never be healthy enough to shrug off any kind of disease.
There are so many roses that do like growing in my conditions, it just doesn't make sense for me to even try a rose that needs special care no matter how much I may like the bloom.
I think they really are not suitable for all gardens and are being marketed as a novelty roses. Great plants where conditions are right, but otherwise, not so much.
Smiles,
Lyn
