Baptisia australis - How to Grow and Care for False Indigo

How to Grow and Care for Baptisia australis, False Indigo

Baptisia australis (False Indigo)
Photo: © Marie Iannotti

Overview and Description:

Blue false indigo (Baptisia australis) is a native American beauty. In fact, Europeans used to pay Americans to grow this plant for the dye they made from the blue flowers. That's why it's called False Indigo. Indigo was expensive and Baptisia grew like a weed. False indigo is a member of the pea family and you’ll notice a resemblance in its foliage and flowers, as well as its fondness for cooler weather.

Baptisia australis is a standout because of its striking blue flowers.

False indigo has an upright, shrubby form. It offers a long season of interest, with flower spikes, seed pods and foliage that is almost never bothered by pests or disease.

  • Leaves: Clover-like trifoliate leaves have a blue-green coloring.
  • Flowers: Pea-like blossoms start as plump, tight buds. The flowers are borne on long racemes and are a vivid blue, often with flecks of cream or yellow. They are followed by seed pods which further demonstrate they are a member of the pea family. The pods persist and turn black and are often used in flower arranging.

Botanical Name:

Baptisia australis

Common Name:

Blue Wild Indigo, False Indigo

Hardiness Zone:

USDA Hardiness Zones 3 - 10

Exposure:

Full sun. False indigo will get floppy without at least 6 hours of full sun light. Full sun also prevents fungus diseases.

Mature Size:

4-5 ft. (h) x 3-4 ft.

(w)

Bloom Period:

Late Spring - Early Summer

Suggested Varieties:

  • Purple Smoke Baptisia X ‘Purple Smoke- A hybrid with a purple eye in the center of the blue flowers.
  • Twilite Prairieblues™ Baptisia × variicolor Twilite Prairieblues™ - A cross between B. australis and the yellow B. sphaerocarpa purple flowers tinged with buttery yellow.
  • White Wild Indigo Baptisia alba  - Similar plant, with white flowers set against dark stems.

Design Suggestions:

False indigo blends beautifully with pastel, late spring bloomers, like peonies, as well as with shocking colors. Spiky plants, like iris, salvia and tall alliums, complement both the color and the texture of Baptisia. The blue blossoms bring out the chartreuse of Lady’s Mantle.

Since it is a large plant and it only blooms once, be sure to put it somewhere in your garden where its foliage will continue to offer interest.

False Indigo Growing Tips:

Soil: False indigo prefers drier soils. It is not particular about soil pH, but does best in a soil that is neutral to slightly acidic.

Planting False Indigo: You can start Baptisia plants from seed, but they are slow to establish and it will probably be 3 years before you see flowers. Even a young false indigo plant will take at least 2 years to get established, before you really start seeing it bloom. On the plus side, they are very long-lived.

False indigo seeds have a hard outer coating. If you do decide to try growing them from seed, some type of scarification will improve germination. Soaking them in hot water for at least 8 hours prior to scarifying them would be even better.

Although, some gardeners have luck simply planting the seeds in the fall and allowing the winter weather to soften the seed coat.

Because false indigo plants have tap roots, they are difficult to divide, however they do grow well from cuttings.

Maintenance:

False indigo requires very little maintenance. Keep it watered regularly for the first year. Once established, Baptisia is very drought tolerant.

You can leave the spent flowers and enjoy the seed heads. The pods are attractive and jingle in the wind. However they can make the plants top heavy and prone to splitting open in the center, especially plants grown in partial shade. You can prevent this by giving your false indigo a modest shearing after flowering.

False indigo leaves turn an unattractive black with the first hard frost and the plants tend to collapse by mid-winter, so cutting them back in fall is usually recommended.

More on adding blue flowers to your garden.

Pests and Problems:

Fungus diseases such as leaf spot, powdery mildew and rust can occur if grown in crowded, damp conditions.

Weevils have been know to eat and infest Baptisia seeds. This can be a big problem if you are saving the seeds to plant. Always check your seeds before bringing them indoors.