While driving through Collin County this spring, the showy flowers of many blue wild indigo plants caught my eye. Our plentiful rains this year seem to have helped the plant grow in above-normal numbers.   

Blue wild indigo (Baptisia australis) goes by many names, including wild indigo, false indigo, Baptisia, plains Baptisia, rattlepod, and rattlebush. It is a native, perennial legume with showy blue flowers. It has deep roots, alternate trifoliate leaves, and reproduces by seeds or rhizomes. Flowers are found in a cluster growing at the end of erect branches between April and August.

Blue wild indigo in bloom

After flowering, seeds growing in pods that are one to three inches long can be found. Once the plant is mature in the fall, it breaks off from its root system. Blue wild indigo may grow up to five feet tall and three feet wide, but is more often three-feet tall and two-feet wide. 

The plant was once used by Cherokees for dyeing clothes and making tea. Other Native Americans used it for medicinal purposes, eyewash, and baby rattles.

Blue wild indigo with seedpod

Today, many people use it for ornamental purposes in their yards because of its showy blooms and low maintenance requirements—it does not require fertilizer, extra watering, or pruning. It is a good plant to use if you are considering xeriscaping. Blue wild indigo is also valuable as a conservation plant: it creates good ground cover, has a deep root system that helps prevent erosion, and, as a legume, it returns nitrogen to the soil.

Blue wild indigo attracts pollinators, but is rated poor for wildlife and livestock. Formerly, it was thought that the plant was lethal to cattle and horses. However, more recent studies show that the plant has less serious, non-lethal effects if grazed. It should also be noted that grazing of the plant is seldom an issue because it contains alkaloids that are bitter tasting. 

Blue wild indigo seedpod

Its range stretches from Texas to Nebraska and eastward. It does not tolerate shade and grows best in sandy or well-drained loamy soils. The plant is highly adaptable and can be grown in many areas outside its native region. Its deep root system allows it to withstand droughts, and it can also withstand extremely cold temperatures for a short time without any damage. 

Weevils are a common pest of blue wild indigo. They invade the seedpod and greatly reduce the viability of seed. If planting blue wild indigo, seeds should be treated to kill insects, and the hard seed coat should be scarified. Germination occurs when the soil temperature is close to 50 degrees Fahrenheit. 

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References:

USDA-NRCS Plants Database. May 31 2012. http://plants.usda.gov/java/profile?symbol=BAAU

Shinner and Mahler’s Illustrated Flora of North Central Texas. 1999.

Botanical Research Institute of Texas. Forth Worth, Texas.