BAPTISIA australis (L.) Small.

wild blue indigo

Georgia<br>Perimeter<br>College Botanical Garden


By Thelma Glover

Wild blue indigo is a member of a large genus of North American summer flowering plants that belong to the bean family (Fabaceae). In the wild it is found in woodland borders, thin open woods and limestone glades from Pennsylvania to Indiana, southward to Georgia and westward to north central Texas. In Georgia, it is found in the Cumberland Plateau region in the extreme northwestern section of the state. Several other species of wild indigo grow in Georgia, including the rare federally endangered hairy wild indigo, Baptisia arachnifera, which is found only in a few counties in southeastern Georgia. All the plants in this genus are unusually attractive and make wonderful garden plants.

Wild blue indigo has enjoyed a colorful past (pun intended). The genus name, Baptisia, comes from the Greek word “to dye” referring to the early use of the plant as a substitute for indigo dye. A yellow species, Baptisia tinctoria, was a source of yellow dye. Various other species of Baptisia have been used as an antiseptic for wounds, as a purgative, an aid for toothache and for relief of rheumatism.

Description: Blue wild indigo is a much branched, bushy shrub like herbaceous perennial growing from 3 to 5 feet tall and 3 feet wide. It has a very deep, tough root system that supports erect asparagus like stems surrounded by bluish green compound foliage that is attractive from April until frost. The deep, blue -violet colored, pea shaped flowers are in terminal racemes that start blooming in the Atlanta area around May l, and last 3 weeks or more. The fruit is a most unusual looking 3 to 5 inch inflated pod which turns a deep grayish-black when ripe , and usually remains attached to the stems throughout the summer. Florist sometimes use the interesting pods in dried arrangements.

Culture: Blue wild indigo is one of those commonly referred to in the nursery trade as a “get your money’s worth” plant. It not only has gorgeous flowers, the foliage alone is sufficient reason to grow it in the garden. It is drought tolerant, undemanding, dependable and long lived. In fact, the entire Baptisia genus has been selected by the Georgia Green Industry as a l996 Gold Metal Plant . This means that it has performed outstandingly in trial gardens for a number of years. Plant it in full sun, give it excellent drainage ( no clay please) and fair soil (tolerates poor soil) with a neutral to basic Ph and it will reward you many times over. Planting or moving it is best done in the fall just before it goes dormant, or in early spring just as the stems are emerging. Like all of the Baptisias, it has a tendency to droop when in a pot or being transplanted, making it necessary to cut the stems back to within an inch or two of the crown. The stems reemerge quickly and stand very erect. Blue wild indigo is one of those plants that needs no pampering; it can be planted and neglected and still thrive.

Propagation from seeds: Collect the seeds of wild blue indigo when the pods have turned from green to black. The seeds are usually mature when the pods begin to split which is mid July at the DeKalb College Garden. Seeds, when ripe, are a yellowish-tan and relatively large. They can be stored dry in a refrigerator for several years, but like other seeds of the bean family, they have a very hard seed coat which must be softened in order for them to germinate. Soaking the seeds in hot water for 24 hours or mechanically scarifying the seed with a file or sandpaper will promote germination. This can be avoided if the seeds are planted fresh soon after they mature. Although most authorities indicate that germination of blue wild indigo is slow and uneven, we have had excellent success with germination with seeds collected as late as October and planted with no special treatment. Typically, seedlings will flower sparsely the second year but will not reach full flowering potential until the third or fourth year.

Propagation by division: Because of the deep tough root system of blue wild indigo, division can be difficult. A sharp axe is needed to cut the large root stock into divisions, making sure there are several buds in each division. The longer, stringy roots should be cut back to a length of 3-4 inches. The divisions should be replanted with the crown just at ground level. From the plants point of view division is never necessary; new plants are easier acquired by seed propagation.

Garden Use: Blue wild indigo is as versatile as it is beautiful. It is striking enough to be used alone, but also looks great planted with other perennials. It is aristocratic enough to fit into a formal perennial border, but it also is at home in a naturalistic setting or meadow. It’s great in front of a white fence or planted in front of taller deep green shrubs. It is outstanding combined with yellow coreopsis, Arkansas amsonia, beardtongue, Carolina bush pea and other species of wild indigo, especially the western yellow indigo, Baptisia sphaerpcarpa. Use the foliage as a backdrop for lower growing perennials such as barbara’s button, lavender, Cumberland rosemary and annual bedding plants.

SOURCES:


Prairie Nursery Sunlight Gardens White Flower Farm
P. O. Box 306 174 Golden Lane P.O. Box 50, Route 63
Westfield, WI 53964 Andersonville, TN 37705 Litchfield, CT 06759
(608) 296-3679 (6l5) 494-7396 (800) 503-9624

Georgia Perimeter College Native Plant Botanical Garden
3251 Panthersville Road
Decatur, GA 30034
678-891-2668

REFERENCES:

Armitage, Allan. 1989. Herbaceous Perennial Plants. Varsity Press, Athens, GA.

Krochmal, Arnold, Russell Walters and Rilchard Doughty. 1969. Medicinal Plants of Appalachia. U.S.D.A. Forest Service. Research Paper NE 138.

Rickett, Harold W. l966-l975. Wildflowers of the United States. 6 Vols. McGraw-Hill, New York, NY.