I grow Great Century, and I have to say I'm not that happy with it. In fact, it's on my shovel prune list. It blooms very infrequently and the blooms are just not that large. I have heard good things about Moonstone on this forum, I believe.

I have both. GC didn't bloom at all this yr for some reason. MOONSTONE is a gorgeous rose if you spray, which I don't. Mine always has thrips damage, and in early season (and late season) has BS. But if you spray regularly, you'll love it!

I'm not in CA, but Moonstone or Cajun Moon (if you can find it) are much better than GC.

Moonstone is the better rose, if you're more than 5 miles from the coast. Here in the coastal foggy zone, it balls so the blooms often don't open. I've grown Great Century before, and shovel pruned it on grounds of stinginess and disease (it's hard to get one without Rose Mosaic Virus these days -- all of the stock is probably infected).

If you like white with pink edge, Lynn Anderson is a better choice than both of them, in my opinion. But if you plant that, then stand back, she's a tall grower.

Kathy

Moonstone likes heat, so should do well in Sunset 18. However it's quite the ruster, so watch out for that.

Other similar roses would be Mavrik, Louise Estes, Lynn Anderson.

Thanks so much you guys, supremely helpful!

I'm coming late to this discussion, so you've probably already made your decision. But since we're in the same zone, I thought I should put in a defense for Great Century. I love this rose! For me, it's a strong bloomer even when I neglect it, and the blooms are huge, especially the spring flush. The plant itself is fairly clean. I grow Moonstone also, and like it as well - it does do well in our heat. But if I had to replace one of the two, I'd choose Great Century.

debora, actually I still haven't bought yet because I wasn't sure if I had room or not. why do you prefer Great Century, then?

I just love the flowers - the color, the size. And I don't have any problems with the plant itself, in fact it seems to like my neglect. This is not to denigrate Moonstone in any way - her flowers are absolutely wonderful, too. But both of them are fairly large plants for me, so if you're short on space, maybe a smaller rose...

BTW, I'm in Pomona, are you nearby?

I grow both and I think that Moonstone is a better rose for me all the way around. It is one of my very favorites.
John

Perhaps another to consider with similar coloring: Secret.

Strong fragrance, good vigor, & average/good disease resistance (I don't spray & it is not growing in full sun, so trying to be fair about this assessment.)

The main problem with all these soft colored roses has already been mentioned by Beth-thrips damage. It can be a real problem, giving you ugly brown-edged blooms unless you have an effective IPM (integrated pest management) balance or a spray program for control. (I have neither!)

Thrips damage has become a bigger problem for me year by year as I've added more roses and have gotten more of a monoculture going on in the yard. Despite it's many good qualities, Secret will probably not survive the next culling to make room for new roses here, but if you can offer better conditions I think it's a fabulous rose. :)

Here is a link that might be useful: Secret at helpmefind.com

I have tried to grow Secret twice in my northwest Missouri zone 5b/6a zone gardens with no success at all.
The plants were not vigorous at all and barely bloomed any at all.
I spray insecticide one time per year usually in mid-May when the thrips come out. I use Merit insecticide and only spray the blooms and buds that are on the bush and stay away from spraying the entire bush as it is unnecessary, wasteful, and less dangerous to the environment. It does an excellent job of killing the thrips and keeping them away because I don't see any of them the rest of the year.
I spray late in the evening after the beneficial bees have gone home to bed. By morning the Merit has dried on the blooms and it doesn't seem to harm the bees that I can see.
John

debora, I'm in the Santa Clarita Valley, not all that close to you, but it's all relative, I guess! Thanks for all the advice you guys!