In my penultimate look at perennials that bridge the gap between spring and summer, I recommend some superb flowers that are tailor-made for carrying your garden through the seasonal transition until the main glut of coreopsis, daylilies, echinacea, hydrangeas, garden phlox and Shasta daisies open their blooms as the mercury soars during the dog days of summer.
Years ago, I grew our native species form of Amsonia tabernaemontana (or willow bluestar, Zone 3), and although it was a beautiful plant that spread around nicely, it did tend to flop! So now I grow the much shorter (up to 45 centimetres) Amsonia ‘Blue Ice’: it does well in average garden soil in a full sun to part-shade location. Generally reckoned to be either a hybrid or a naturally-occurring dwarf form, it was discovered growing in a row of A. tabernaemontana seedlings at White Flower Farm (Connecticut), and looks best when planted in groups of three or more.
There are about 20 species of Baptisia, and all of them are native to North America. Baptisia australis (or false indigo, Zone 3) pictured above, was still a rare plant when I began gardening, and it was with some difficulty that I begged a division from a gardening friend. All baptisias grow well in average garden soil in a full sun to part-shade location (more shade results in fewer flowers). Like peonies, baptisias resent disturbance, so choose your location carefully, and then let them get on with it!
Over the past 20 years, baptisias have at last managed to attract the attention of plant breeders, and the results have been spectacular. The first of these hybridisers was Dr. James R. Ault at the Chicago Botanical Garden, who began his baptisia breeding program in 1995.
B. ×variicolor ‘Twilite’ (pictured above, in bud) was the first introduction (2008) in Jim Ault’s now famous baptisia Prairieblues Series. ‘Twilite’ bears dusky rose buds which open to purple-burgundy flowers with yellow keels. The result of a 1998 cross between B. australis and the Midwestern yellow wild indigo (B. sphærocarpa), I grow it in front of a purple-leaved ‘Red Majestic’ corkscrew hazel (Corylus avellana, Zone 3).
B. ×bicolor ‘Starlite’ (pictured above) was Jim Ault’s second introduction in the Prairieblues Series, and was released in 2009. The result of a 1998 cross between B. australis and B. bracteata, it bears lavender-periwinkle blue flowers with buttercream keels, and has a strong, upright habit. In addition to ‘Twilite’ and ‘Starlite’, there are now 10 more new cultivars in the Prairieblues Series, all of them excellent additions to the early summer garden, although several are not slated for general release until 2015—but they promise to be well worth the wait!