I can never get enough blue flowers in my garden!
Blue is such a calming shade and happily combines with any other color. In the spring, I love grape hyacinth and Virginia bluebells. The bluebells were first discovered in Virginia, hence the name, but they grow and are native to the Midwest and indeed are native to many other parts of North America.
I love the blue flowers on ajuga and campanula and perovskia (Russian sage), salvias, and the lupin-like spires on baptisia.
I grow a lot of short lavender-blue nepeta, commonly known as catmint. My current favorite is ‘Cat’s Pyjamas’, which is 18-20 inches tall. I use the flowers in bouquets and cut the plants back hard after their first bloom so another lot of flowers come again later in the summer. It is good for stifling weeds.
I can’t grow delphiniums because Midwest summers are too hot, but each spring I buy packets of larkspur seeds and sprinkle them in my perennial beds with abandon, as I love their violet-blue color. Some of these annuals even come back.
In the fall, my low-growing plumbago blooms with the added bonus of leaves that turn dark red.
My caryopteris shrubs, with grey foliage, are electric blue in autumn if they are in well-drained locations and if I remember to cut them back each spring.
I also love blue borage (botanical name Anchusa), blue morning glories, and asters, especially the powder blue ‘Marie Ballard’.
[Note: Remember borage can be invasive. Also try stokesia, veronica and vitex, which is a shrub in the Midwest that dies to the ground in winter and returns in the spring.]