I've had G. Rozanne in my garden for quite a few years. I'm somewhat disappointed with its lack of vigour and flowering. Recently I went to my fav. nursery to purchase a couple of new specimens, with the hope to get more flowers in the G. Rozanne patch. They didn't have any, and suggested G. 'Orion' as a very similar replacement. These 2 cultivars are indeed very similar, although not identical. The foliage is definitely different. There is really not much difference in their shade of blue. I'm attaching 2 pics for comparison. Please note that blue is a very difficult colour to render in photography.
Just found my Rozanne, yes much taller this year, All the plants have loved that rain this year, perfect timing, I’ve got lupins and aquilegia as tall as me, all looking good. The Rozanne always looks like it’s flowering through a load of buttercups. I’ve got better ones in the garden.
Gardening on the wild, windy west side of Dartmoor.
I don't think Orion is related to Rozanne either. Rozanne is a wallichianum type, which has slight pale marbling on the leaves. As @Papi Jo says, Orion has more finely cut leaves; it's similar to Brookside which according to the RHS is a G. bohemicum sport. My mum has Brookside which is a show-stopper in full flower (Rozanne is never a show stopper IMO) but starts looking like it's going over in late summer, while Rozanne carries on playing an important supporting role pumping out fresh foliage and blue flowers right into Autumn.
"What is hateful to you, do not do to your neighbour".
Another difference in my experience, Brookside/Orion will revel in a fairly hot dry spot, whereas Rozanne is happier in a cooler position or sprawling in the shade of taller perennials. Rozanne can go limp in direct sun in dry weather.
"What is hateful to you, do not do to your neighbour".
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Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
The Rozanne always looks like it’s flowering through a load of buttercups. I’ve got better ones in the garden.
I'm not sure. The flowers do look very similar. The more distinctive features are the habit and foliage. G. Orion's foliage is much more dissected.
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.