Baptisias take centre stage

When I learned on New Year’s Day that blue false indigo (Baptisia australis) had been selected as the Perennial Plant Association’s Perennial of the Year for 2010, I wasn’t in the least surprised. Had I been on the selection committee myself, I certainly would have cast a supporting ballot. Once a special-order item, baptisia’s recent promotion to “brag plant” status (thanks to its hot new cultivars) should finally ensure wider availability for this striking, statuesque, but sadly underutilized flower.

The Baptisia genus comprises about 17 species, most of which are native to the southeastern U.S., two notable exceptions being B. australis, whose wide range extends from the Atlantic seaboard west to the Rockies, and B. bracteata, which is at home from Texas north to Manitoba. The common name false indigo refers to the plant’s use in Georgia and the Carolinas as a substitute — albeit a poor one — for genuine West Indian dyers’ indigo (Indigofera tinctoria) during the 18th century.

Baptisia flowers are borne on impressive racemes and, taken individually, look similar to their near relations: lupines and sweet peas. Like all members of the Papilionaceae family, baptisias fix atmospheric nitrogen through nodules on their roots, improving soil fertility as they grow.

Most species flower in late spring or early summer, and then sport handsome grey-green foliage (often likened to eucalyptus) for the rest of the season, with mature plants assuming shrub-like proportions (mercifully they don’t require staking). Like hellebores and peonies, baptisias are long-term perennials, so choose a site in full sun and then leave them alone. They rarely need dividing and resent being moved. I add a handful of bonemeal and several spadefuls of well-rotted manure to each planting hole; some additional irrigation may be required during dry spells in the first year; however, once established, baptisias are extremely drought tolerant.

Baptisias are virtually pest- and disease-free, although where hungry voles abound, roots may be attacked. Annual maintenance is confined to scratching in one or two inches (2.5 to 5 cm) of compost or well-rotted manure around the crown of each plant in early spring, and cutting back spent foliage in late autumn, or early spring the following year.

When I purchased my first Baptisia australis 15 years ago, there was no such thing as a baptisia cultivar, but happily, at about the same time, James Ault began a baptisia breeding program at the Chicago Botanic Garden. Meanwhile, Tony Avent of Plant Delights Nursery in Raleigh, North Carolina, had begun working with the late Rob Gardner, a curator at the North Carolina Botanical Garden: their aim was to select and propagate outstanding plants from existing wild populations. Each of these programs has been greatly assisted by bees and the natural promiscuity of the plants themselves — so much so, that even wild populations often turn out to be complex interspecific hybrids.

The fruits of these initiatives are only just beginning to trickle down to gardeners, who are now fortunate enough to have a far greater — and ever widening — palette of cultivars to choose from. Here are 10 of the best:

Species and selections of baptisia

Blue false indigo (Baptisia australis)

The most commonly grown and hardiest (to Zone 3) form — usually propagated by seed. Butterfly-attracting violet-blue flowers in early summer are held above blue-green foliage, followed in autumn by large, ornamental, grey-black seed pods (much relished by chickadees). Clumps grow three feet (90 cm) tall and wide, and may be divided every five years if you want more plants.

‘Screamin’ Yellow’ baptisia (B. sphaerocarpa ‘Screamin’ Yellow’)

Native plant expert Larry Lowman made this selection of B. sphaerocarpa from a wild population in Arkansas, and introduced it in 2002. Although currently difficult to find, it should become more readily available in the next few years. Hardy to Zone 5, it produces 10-inch (25-cm) racemes of brilliant yellow flowers held above bright chartreuse foliage on a three-foot (90-cm) tall by four-foot (1.2-m) wide plant.

‘Wayne’s World’ baptisia (B. alba var. alba ‘Wayne’s World’)

A vegetatively propagated clone (from cuttings) of a selection made by Tony Avent from wild seed collected in Wayne County, North Carolina. Hardy to Zone 4, it forms a clump four feet (1.2 m) tall by three feet (90 cm) wide and bears long (18 inches/45 cm) racemes of white flowers held high above grey-green foliage in early summer.

‘Butterball’ baptisia (B. bracteata var. leucophaea ‘Butterball’)

A compact form of baptisia that grows just 18 inches (45 cm) tall by two feet (60 cm) wide. It produces large, pendulous racemes of creamy yellow flowers framed by glaucous foliage. Hardy to Zone 5, it’s another Avent selection, introduced in 2008.

‘Purple Smoke’ baptisia (B. ‘Purple Smoke’)

The first of the late Rob Gardner’s introductions (1996), ‘Purple Smoke’ is a chance cross between B. minor and B. alba. It grows four feet (1.2 m) tall by 30 inches (75 cm) wide and bears upright spikes (18 inches/45 cm) of smoky violet flowers on charcoal stems with grey-green foliage; hardy to Zone 4.

‘Carolina Moonlight’ baptisia (B. ‘Carolina Moonlight’)

Discovered by Gardner at the North Carolina Botanical Garden as a random seedling (a cross between B. sphaerocarpa and B. alba). It’s hardy to Zone 4, and grows four feet (1.2 m) tall by three feet (90 cm) wide, producing upright spikes (18 inches/45cm) of butter-yellow flowers over blue-green foliage. Introduced in 2002.

Baptisia hybrids

‘Twilite’ baptisia (B. x variicolor ‘Twilite’ Prairieblues Series)

The first Baptisia cultivar to be released (in 2008) by James Ault, director of environmental horticulture at the Chicago Botanic Garden, who calls it “baptisia on steroids.” A cross between B. australis and B. sphaerocarpa, it grows five feet (1.5 m) tall by four feet (1.2 m) wide and produces bicolour violet-purple flowers with a yellow keel above blue-green foliage; hardy to Zone 4.

‘Starlite’ baptisia (B. x  bicolour ‘Starlite’ Prairieblues Series)

The second baptisia cultivar to be released (2009) by the Chicago Botanic Garden, a cross between B. australis and B. bracteata, it grows 40 inches (1 m) tall by five feet (1.5 m) wide, and blooms two weeks earlier than most baptisias, sporting bicolour lavender flowers with pale yellow keels held above light green foliage; hardy to Zone 4.

‘Midnight’ baptisia (B. ‘Midnight’)

New for 2010 from the Chicago Botanic Garden, ‘Midnight’ grows four feet (1.2 m) tall and wide, and is hardy to Zone 4. An open-pollinated seedling of an unnamed hybrid (B. tinctoria x B. alba) and B. australis, it produces primary violet-blue flowers on two-foot (60-cm) -long racemes followed by a second flush on four-inch (10-cm) -long racemes, effectively extending the bloom season by 10 days.

‘Solar Flare’ baptisia (B. ‘Solar Flare’)

Also new for 2010 from Ault and the CBG, an open-pollinated seedling of an unnamed hybrid (B. tinctoria x B. alba) and an unknown pollen parent, ‘Solar Flare’ grows four feet (1.2 m) tall by five feet (1.5 m) wide and, like ‘Midnight’, produces a second flush of flowers, extending blooming time by 10 days. Hardy to Zone 4, it displays racemes of yellow flowers that age to deep yellow with a distinct orange-violet cast.

Did you know?

Baptisias produce large, shiny greyish-black seed pods, and a few stems are a dramatic addition to floral arrangements. When left on the plant, the dried seeds rattle in their pods during a light breeze. Legend has it that the pods were used as children’s rattles in earlier days.