A highly prized perennial

It is blue-butterfly day here in spring,
And with these sky-flakes down in flurry on flurry
There is more unmixed color on the wing
Than flowers will show for days unless they hurry.
But these are flowers that fly & all but sing:
And now from having ridden out desire
They lie closed over in the wind & cling
Where wheels have freshly sliced the April mire.
-Robert Frost
(1874-1963)

Virtually every British gardening print sings high praises for these undisputed regal blooms. In the US, I read that they were hardy in Zones 3-8. Now, I am pushing Zone 10 in coastal San Diego, but I must have these splendid blues. So, I've tilled in copius amounts of compost and gypsum into the soil and used it it to edge a part of patch 1. I've mulched it an inch or so to keep the roots cooler. I'm hoping this sees it through our summer sun. For now, it delights the hummingbird as much as it warms my heart.