Dudleya cymosa

I can't answer your question, but side-tracking slightly...
I just looked up the Alplains catalogue and found that seeds for a number of Dudleya species are offered:
http://www.alplains.com/Catalog4.html
The suggested zone ranges for the various species and forms are 6 through 10... (but who knows until they try them?)  Perhaps at least a couple of those might be worth trying in your area, Charles?

Coincidentally, I had an extensive conversation with Bill Adams of Sunscapes this past week about Dudleya cymosa cultivation. According to Bill it grows during the winter and spends the summer in a sort of moderate dormancy. So although it seems to be hardy here, it just slowly diminishes year after year until it dies unless it's given some winter weather above 35 degrees and some sun, so it can grow. A greenhouse that keeps it 30 and above is probably the best plan for it here in MA. I grew it a few years ago from Alplains seed and it wintered over twice, but didn't come back the 3rd year, and it really never got bigger than a half dollar and it never bloomed.

I have tested a good number of so called Z6 Dudleyas. They look so wonderfull and are very tempting to grow. However, of more than a 100 plants Im left with only one and that is growing them in an unheated greenhouse in winter. Yes, they can tolerate a lot of frost, but they also want to grow in winter even with the relative mild summers of Denmark. And winters just not a good time to grow here up north so they die. One by one.
They are not hardy, they can just take an occational frosting but need warmer temps most of the time and a lot of sun.
Martin

Great looking plants, have seen them in the wild in California high up in crevices on the remains of an ancient volcano (pinnacles national monument).
Definitely winter growers there.
Thanks to: Lori, Peter and Martin for doing the homework on Dudleya.
I look out in my garden, where some of the Crocus Cyclamen Alliums and Lewisia rediva, are just starting to grow as the growing season here ends; and think about how far rock gardening has come and how much we still need to learn.
Lewisia rediviva benefited fully from winter growth in central coastal California.  But doesn't it grow in Wyoming, too???

(at least my cacti seem to know when to sleep -- at least so far, some of the Echinocereus are getting rather large to look as if they should be outside in the winter here ;-(      )

Charles Swanson NE Massachusetts Z 6A +/-

My Lewisia rediviva are from Idaho and the start to regrow in late winter early spring and than go dorment in mid summer.

My Lewisia rediviva hasn't come up more than 1/2 inch -- wish I could say as much for numerous Alliums and Colchicums.
Some cacti have shrunk to 1/3 size, others just a little.
Had a record damaging snow last weekend, now forecast a few days in low 60s F.
Will watch for a source of Lewisia rediviva from the NE of it's range.
At least the Calochortus haven't come up  -- either a good thing or a bad thing.

Charles Swanson NE Massachusetts z6A

Lewisia redivivia var. minor from Eastern Nevada can be found growing as high as 8-9 thousand feet  on exposed ridges. I'm sure at times the snow blows off in the winter winds but you can also find large populations growing on southern and western exposures sheltered by sagebrush.

The redivivia plants start to send up leaves in November and December. When it gets cold (into the teens) they revert to a  semi dormant state until the weather warms in March. You will then see the leaves elongate until late May/early June. They don't mind wet clay soils in the winter and spring but need dry soils in the summer.

I am trying a Dudleya cymosa this year. So far it looked very sad this summer, no growth at all. 

I have been sent some seed of this species. Given its dust like nature there must be many hundreds, if not thousands, of potential new plants in the packet. 

Can anyone provide sowing and growing on advice please? TIA

Just generally, try some surface sown on pasturized well-draining soil mix 3 or 4 inches under fluorescent light.  Cover with plastic wrap, vent when well germinated, but don't allow to completely dry.  (Pour boiling water on the seed mix a couple of times cool and plant)  Germination may occur within 2 to 3 weeks.

Thank you, I'll give that a try.

Wrightman's Alpines in Ontario (z5?) was offering a D cymosa, I think, and it had been doing well for them outdoors if I recall, I wonder if it still is?

Well, they are still offering it: http://www.wrightmanalpines.com/plant/dudleya-cymosa  and say it is much admired by garden visitors..

Oddly they call it a Lewisia relative, are not Lewisias Portulacaceae or whatever it may be called now, and Dudleya Crassulaceae?

Cohan, the link wasn't working, but was able to fix it.  Boy, that's one showy succulent with those hot color flowers, I'm tempted to order next spring if he has any left. I have received plants of this in the autumn before, and they didn't overwinter, so want to allow them the whole season to become established.