Several years ago I bought a plant of Browallia americana, amethyst flower, to grow in a container. This beautiful shade loving annual has a lot more grace than the typical dwarf version that is popular at garden centers. According to local plantsman and garden blogger Gary Keim (http://planetplant.net/) there are two forms of Browallia americana. One reaches 3 feet tall with cobalt-blue flowers and the other form, which is the one I have in my garden, is shorter reaching only 18 inches tall with azure-blue flowers and a white eye. Gary likes to combine them with dahlias and the fall blooming Anemone x hybrida. He feels that the airy aspect of the Browallia contrasts nicely with the bolder foliage and flowers of the aforementioned species.
At the Arboretum, we used Browallia americana in our summer containers found in the Scott Entrance garden, Terry Shane Teaching Garden, and Cosby Courtyard. Since my original container planting at home, Browallia americana now serendipitously pops up in the garden every year. This year it came up under an outdoor garden table where there is also a seedling of Heuchera villosa. Today both are in full flower. The blue of the Browallia makes a striking combination with the white spikes of the Heuchera villosa.
Browallia americana can often be found through mail order nurseries that specialize in unusual annuals like Annie’s Annuals (www.anniesannuals.com) or through a seed exchange such as the Mid-Atlantic Hardy Plant Society’s exchange (http://www.hardyplant.org). Once you procure it you will never have to plant it again.