I grow and love both roses. For your climate it shpould be Duchesse de Brabant, no question in my opinion. JC will most probably be meserable at your place.
Olga

I don't know about JC, but the Duchesse will perform just fine. When I lived in Columbia, SC, I saw this rose growing well at the Riverbanks Zoo & Garden. It is in the 90's/humid there for months at a time. There is also a bush (receives no care except weed whacker assaults) in Hollywood Cemetery in Richmond VA that grows well in a similar, but not quite as hot climate.

Thanks Olga and jbcarr.

Olga, I have just been looking at Barbara Wilde's book and she says, "Because it tolerates heat well, [JC] is one of the best repeat-flowering old roses for the South". What do you think? Could it grow well in zone 10?

Thanks
Joanna

Joanna, I really don't know. You can try. I only know that I used to grow this rose before when I lived in CT, where summurs were not so hot as here in MD, and JC was much happier there. Hopefully people from warmer zones can give some feedback. It is still very good here, but I know it could be happier. During summer months leaves start looking kind of bad, which never was the case in CT.
Do we have any forumers from TX who grow JC?
Hope somebody will respond.
Olga

I am in Northern CA and I grow both roses. I do not get much humidity here, but do get a lot of heat. As my JC matures, I am noticing that it is less disease prone than it was. However, DdB is totally disease free and blooms all the time. JC is also very gangly and the blooms blow quickly here, while DdB has more color on the bush at all times. DdB is a more rounded bush, like most Teas. I frankly think that DdB is hard to beat when it comes to disease free performance in my climate.

Can I assume that JC is the same rose as what most sources in the US sell as Marchessa Boccella / Marquise Bocella? If so, there are some of them growing quite happily at the Fort Worth Botanical Garden here in Texas.

And as for the Duchesse, there are lots of them around here, and they always look good to me.

Randy

Two very nice and very different roses. For me, there is no doubt I would choose Duchesse de Brabant. Health, beauty, foliage, pretty leaves, nice blooms, good repeat, no fungus. Jacques Cartier smells beautiful when it blooms. The plant is not as pretty as I woud have liked. It either had blackspot or rust constantly and it did not bloom as frequently as I would have liked and the blooms were fewer in number. Might be a totally different story elsewhere, but Mr. Shovel took my JC out of its misery.

I also have both (one Duchesse de Brabant and two Jacques Cartier). I told JC day before yesterday that he better have a better year next year or he's out. I like DdB much better. The bush has a nice shape, foliage is good and blooms are really nice. JC is more susceptible to BS, the Japanese beetles like it better and the bush shape is not as good as DdB. I'd probably keep it if it bloomed more and if it didn't defoliate so easily. Just my opinion but since you asked... Jeff

Between the two the Duchess is the rose to plant. Much faster rebloom and a nicer looking bush. JC smells better but that is its one stronger point.

Lance

FWIW, in the more-arid Southern half of CA, Duchesse de Brabant is a mildewer.

Jeri (SoCalif)

Jacques Cartier & D de Brabant both do well here in coastal southern CA (I'm south of Jeri near Venice Beach). My garden is a bit too coastal for the Duchesse at times. Jacque Cartier is best in spring when it's cooler. It slows down in the hotter later portio of summer. But I still get several bloom cycles over 10 months. It is the most heat tolerant Portland or Hybrid Perpetual kind of rose I've grown. I would think that Teas would do pretty well for you given your location as long as they don't mildew. My garden isn't quite hot enough for them except in the fall.