Best of all in areas where water may be rationed, Indigo’s deep taproots help established plants weather droughts. These charming North American perennials were certainly the most talked-about plant on June garden tours in the northeast this year. Members of the Pea family, they resemble a rather casual lupine, but are generally much less fussy and have their own charming style. Spikes of indigo-purple, yellow, or white flowers are followed by a short inflated pod. Both flower and fruit are attractive in arrangements, and the foliage - compound leaves with 3 leaflets - looks lovely in the garden.
The name Wild or False Indigo was given to this genus because the sap turns blue when exposed to air, and can be used as a dye, although not as long-lasting as True Indigo, Indigofera tinctoria. Even the botanical name, Baptisia, comes from the Greek word Bapto, which means “to dye“.
Wild Blue False Indigo or Plains False Indigo, Baptisia australis (formerly called B. caerulea) has a wide natural range from New Hampshire to Georgia and Texas. It has blue-violet flowers from May - July depending on where in the country it is grown. Extremely hardy, to zone 3, this plant grows to 6 feet. It prefers moist to average soil but like most in this genus it is very drought tolerant.
The Wild Indigo species most often used as a dye plant, Baptisia tinctoria, is also known as Horsefly, Horsefly Weed, or Rattleweed. Bright yellow flower spikes bloom at the top of 4’ tall plants from Massachusetts to Florida and west to Minnesota. This one is seldom available in nurseries, although it is a pretty enough perennial.
Largeleaf Wild Indigo or Prairie Wild Indigo, Baptisia alba macrophylla (formerly B. leucantha) prefers partial shade. This 3-5’ tall plant with creamy flowers grows from Ohio to Minnesota and south to Missouri and Texas.
Thick Pod Wild Indigo or White Wild Indigo, Baptisia alba var. alba (formerly B. pendula) can be grown in gardens throughout the US despite its far narrower natural range, North Carolina to Florida. This . 2-3’ tall species has white flowers followed by thick, black drooping pods. A particularly showy new variety is ‘Wayne’s World’ recently introduced by Plant Delights Nursery, NC. It is a wonderful choice for an all-white garden. Baptisia alba is also one parent of two charming hybrids:
‘Purple Smoke’ (B. alba X B. minor) is aptly named with its gray green foliage and muted purple flowers while ‘Carolina Moonlight’ ( B. sphaerocarpa X B. alba) shines with pale yellow flowers.
Yellow Wild Indigo Baptisia sphaerocarpa (formerly B. viridis) is vivid yellow on 2’ tall plants, followed by rounded pods. Hardy to zone 4, this is not only very showy but reliably heat and drought tolerant. The variety ‘Screamin’ Yellow’ has tall spikes of flowers on yellow-green foliage.
A number of other Wild Indigos, mostly from the southeastern US, also deserve a place in the garden. Catbells, Baptisia perfoliata has yellow flowers in early spring and round pods similar to Yellow Wild Indigo. Its smooth gray foliage looks very similar to Eucalyptus, and is a great contrast to the green leaves of other garden plants. Grayhairy Wild Indigo, Baptisia cinerea, has whitish felty leaves and stems with yellow flowers, and thrives in very dry, sandy soils. Scareweed, Baptisia simplicifolia, has pale yellow flowers which bloom in midsummer above very shiny green foliage. Despite the fact that it is found only in Florida, Scareweed is hardy to zone 5.
Wild Indigos have many virtues in the perennial border, meadow, or cutting garden. They attract butterflies and are very lovely low maintenance plants. Whether used in an all-native garden or a more traditional bed with plants from diverse backgrounds, Wild Indigo’s height, showy flowers, and attractive foliage make it a natural focal point.
