I'm almost afraid to call these flowers blue anymore, after reading an interesting conversation at Gardenweb.com (Why Blue?) about blues in the garden and their effect on people. But the iris above is seriously the bluest one I've ever seen. Still, there are some plants that have virtually no red (Plumbago, Myosotis, Mecanopsis); they may come closer to true blue than any of the flowers I have pictured here. If you're a purist, please forgive me.
It's kind of beside the point, though. Whether you think these are blue, sort of blue, or downright purple, they all add the perfect cool color contrast to all the yellows and creamy whites in bloom in the spring.
I snapped the photo of the beautiful blue iris in the Elizabeth Lawrence garden a couple of years ago. It was so stunning mingling with yellow wallflower. There are too many blue/purple iris cultivars to name, and in just about any height you like, from under ten inches to over three feet. There's sure to be one for any blue-loving gardener.
My personal favorite iris is our native Iris cristata. Sticking with native plants, and a blue and yellow theme, you could try underplanting this one with Green-and-Gold (Chrysogonum virginianum). Green-and-gold's yellow flowers nicely echo the crinkly yellow signal of the iris falls.
A ground cover blue which works well in fairy or miniature gardens is Veronica 'Waterperry Blue'. In my garden this plant mixes with mazus (available in white or blue/purple) and chartreuse sedum ('Angelina'), filling in around flagstones. I love the adorable faces of these blooms and the tiny-budded flower spikes. Perfectly proportioned deep green leaves and red stems make 'Waterperry Blue' especially pretty. At full height, the plant is barely 4 inches tall.
A good blue for attracting wildlife to the garden is mountain bluet (Centaurea montana). Butterflies love it. The foliage is slightly silvery from fuzzy white hairs which play up the blue of the flowers nicely. In some areas mountain bluet can spread rather vigorously. But at two years old, mine is a nice, neat clump with no runners. It will be about a foot tall by mid-May. There are several cultivars available. 'Black Sprite' is truly dark enough to look black (another garden color that can cause some discussion), and 'Amethyst in Snow' has a dark purple center with white rays. I am partial to that one.
What do you think of blue in the garden? Are you nuts for it, or does it bore you? Do you have a favorite blue flower, or is blue foliage more your thing?