Very nice, Mike. How recent is this picture? This week? Just curious because I don't know when it blooms; and thanks for sharing!

The picture was taken on 4-21.

Glad you asked. :-)

Mike

pretty

That's a fine blue lepidote. You also have 'Ilam Violet' in your garden, right? Which do you like better?

In a spot with a cool root zone, R. augustinii has done much better than expected for me here. I have crossed with with a known east coast hardy blue so it will be interesting to see what comes of that cross. I am raising 4 of them but they are still years from blooming.

You're right, I do have Llam Violet. It's larger and faster growing for me in the same partial shade conditions than Blue Diamond. If I were going to plant both on a combo I would put the Blue Diamond in front and to one side. I imagine they would go good together in a low level sub-alpine design. With enough light, they both have a tight canopy. I like Blue Diamond because of the blooms. I think they're a prettier blue than Ilam Violet.

You have a good memory. :-)

Thank you, David. Beautiful gardens and mansion.

Rhododendron augustinii is characteristic of sunny sites in nature so maybe it has an associated adaptation to higher temperatures also.

Yeah, probably does. Small leaves makes it easier to tolerate extremes, heat, cold, wind, exposure, etc. (Hi Ron!)

I was saying maybe augustinii is more heat adapted than usual. Otherwise another aspect to the topic is I think Blue Diamond is listed as a Group in Britain and perhaps Ilam Violet also. Which means that more than one cultivar is known to be grown under the name. The practical aspect of this is that one person's Blue Diamond may not be quite the same as another's.

Later:

Search for plants in the RHS Horticultural Database / RHS Gardening

And:

Search for plants in the RHS Horticultural Database / RHS Gardening

So apparently the second variety is considered a single cultivar, unlike the first.

These are so beautiful! Do you think there is anyway to coax them into growing in Metro Atlanta, Georgia?

That's a long shot. I would try 'Crater Lake'...some research by Japanese horticulturalists show it to be one of the most heat resistant blue lepidotes, although 'Cerulean Mist' has done well for me, too. There is also a 'Hardy Augustinii' cultivar out there but it was almost identical looking to Crater Lake, and was selected in the NYC area so may not really be any more heat resistant.

Plant on a north facing slope with well-drained soil, in a place with morning sun, afternoon shade.

I would definitely avoid most of the ones in commerce these days, like 'Blue Baron'. If Werner Brack couldn't grow it on Long Island, you're not going to grow it in Atlanta.