The blue indigo plant – Baptisia australis [bap-TEE-zee-uh aw-STRAL-iss] is an herbaceous hardy perennial flower and a member of the pea family Fabaceae, along with the perennial sweet pea vine.
It was the Perennial Plant Association’s 2010 Perennial Plant of the Year.
It grows naturally in thickets, rich woods, and along the banks of streams in the southeastern United States.
Its genus name is derived from the Greek, bapto, which means to dye.
The specific epithet, australis, means southern.
The plant’s common name, Blue False Indigo, is a reference to the use of this plant as a substitute for true indigo to make blue dye.
You may also hear the plant referred to as:
- Blue Wild Indigo
- Wild Blue Indigo
Other varieties include:
- Baptisia Purple Smoke – Hybrid, purple eye in the center of blue flowers.
- Baptisia Twilite Prairieblues – Cross between B. australis and yellow Baptisia sphaerocarpa purple flowers tinged with buttery yellow.
- Baptisia White Wild Indigo (Baptisia alba) – Similar plant with white flowers set against dark stems.
Blue Indigo Plant Care
Size & Growth
This upright perennial has a height and spread of about 3′ – 4′ feet.
Mature plants produce racemes adding an additional 12″ – 24″ inches to their height.
The foliage is bluish-green and looks somewhat like clover.
The trifoliate leaves are dark blue-green to light yellow-green in color.
The leaves grow so dense they have a shrub-like appearance.
Flowering & Fragrance
Don’t expect Baptisia to flower the first season.
It can take as long as 3 years for the plants to mature and produce blossoms.
Blue Wild Indigo blossoms appear from May through June in the second year.
They closely resemble the blossoms of lupines, pea plants, and sweet peas.
Attracts butterflies and pollinators.
Indigo blue flowers (pea-like flowers) appear on tall spikes high above the foliage.
Flower spikes stay in bloom for about 6 weeks during the late spring and early summer.
The flowers transition into large seed pods and then become deep black when they are ripe.
They’re lovely when added to dry flower arrangements.
They are also quite interesting because the seeds rattle inside the pods.
At one time, these seed pods were used as children’s rattles.
Bloom time: April, May, June, and July.
Light & Temperature
This plant does best in full sun to partial shade.
The plant is winter hardy in USDA hardiness zones 3 – 9.
Watering & Feeding
These drought-tolerant plants require little watering.
They’re very low maintenance and need fertilizing annually in early spring.
Soil & Transplanting
Blue False Indigo does very well in all sorts of inferior soil.
It can thrive in shallow, rocky, dry, and clay soil but prefers moderate soil moisture best.
Baptisia has a very deep taproot, allowing it to survive long dry periods but making it a challenge to move.
Grooming & Maintenance
Once Baptisia is established, it will need little or no care.
If you grow False Indigo in a shady location, the plant may stretch and become leggy, requiring the need for support.
Deadhead flowers or shear the flowers back when blooming is complete.
This will encourage more blossoms and also supports the plant to maintain a more attractive and rounded appearance after the flowers have gone.
Some gardeners prefer to allow Blue Wild Indigo to go to seed because the seedpods are quite attractive.
How To Propagate Baptisia australis
It’s best to allow your plant to reseed itself.
If you do need to start a brand-new Wild Indigo patch, it’s important to note fresh seeds germinate more quickly and easily than dried seeds.
When gathering your own Baptisia seeds, examine them carefully for tiny holes.
There is a type of weevil that chews holes in the seeds of the plant.
If you find seeds with holes in them, throw them away because they will not germinate.
- To speed up germination, pour very hot water over the seeds the night before planting to soften the seed coat.
- Allow them to soak overnight.
- Poke the seeds directly into the soil about ½ an inch deep in a sunny location after all danger of frost has passed.
Baptisia also propagates by using stem cuttings.
- It’s best to take your cuttings early in the springtime using fresh, not woody, growth.
- Cuttings should have a minimum of one pair of leaf buds.
- Dip your cutting in rooting hormone and plant it in a light, airy growing medium.
- Use a plastic tent or glass jar to ensure humidity is high and consistent around the cutting.
- You should notice new roots forming within a couple of months.
Propagation by division is not recommended because the plant’s root system may extend as far as 12′ feet into the ground.
Establishing False Indigo can take a long time, but once it’s established don’t disturb it.
Blue False Indigo Pest or Disease Problems
These natural wildflowers are not bothered by diseases or insects as long as you provide a bright sunny setting and do not overwater.
The plants produce alkaloids, which naturally repel most insect pests.
If you do see caterpillars on these plants, let them because they’re probably beneficial butterfly caterpillars.
Voles do sometimes feed on Baptisia roots, but since the root system is so extensive and so deep, little damage occurs.
Is Baptisia Toxic or Poisonous?
Some plants in the same genus are toxic, so it’s best to avoid consuming the plant.
False Indigo has some uses in Native American folk medicine.
It was brewed as tea for use as a purgative, emetic or to stop vomiting.
Pounded roots were used as a poultice to reduce inflammation.
Is Baptisia Invasive?
As a native plant in the United States, Baptisia australis cannot be considered invasive in the US; however, it is hardy and robust.
Once established, the plant spreads vigorously and is difficult to eradicate due to its deep, traveling root system.
Minimize spread by deadheading to prevent seed dispersal.
Suggested Uses for Blue Wild Indigo
Blue False Indigo is a perfect choice for naturalizing.
It’s quite helpful when planted in areas troubled by erosion because of its extensive and deep root systems.
Plant it in a garden, an open field or meadow, a prairie, cottage gardens, or in borders.
The flowers were once used as indigo but now are only viewed as good garden plants.
The attractive bluish-green foliage acts as a backdrop for flowering plants in late summer.