Wild Blue Indigo (Baptisia australis) Quick Facts:
Common names: Indigo Weed, Rattle Weed, Rattle Bush, Horsefly Weed
Fabaceae (Pea) family
Native to most of central, northeast and southeast US and eastern Canada
Hardy in USDA zones 4-9
Prefers fertile, moist, well-drained soil but drought tolerant once established
3-4 feet tall by 3-4 feet wide
Propagate from seed, rub between sandpaper to scarify, plant 1/4 inch deep, germinates in 1-2 weeks, bottom heat improves germination.
2-3 years from seedling to flower
Baptisia australis for Butterflies!
This little shrub is one of the few host plants that will host several species of butterflies. Orange Sulphur, Clouded Sulphur, Frosted Elfin, Eastern Tailed Blue, Hoary Edge, and Wild Indigo Duskywing butterflies all use Wild Blue Indigo as a host plant to feed their caterpillars! On top of that it is a beautiful plant to have around.
Wild Blue Indigo Characteristics
Wild Blue Indigo is native from PA to south IN, south to GA and TN, introduced in New England, Canada (hardy in USDA zones 4-9); rare near the Gulf and Atlantic coasts. Its native habitats include wood edges, creek beds, and prairies.
It is a herbaceous perennial with a dense, attractive, shrub-like appearance that grows about 3-5 ft high and 3 ft. wide. Mature plants (at least 2-3 years old) are filled with blue to violet flower spikes and flowers from April-August (depending on geographic location).
The grayish-blueish green foliage is alternate and trifloliate (clover like). Its stems are stout and smooth. If a leaf or stem breaks off, its sap will turn a slate blue color when exposed to air. Note: Some parts of this plant are poisonous if ingested.
In order to somewhat control its size and to prevent flopping foliage, established specimens could be trimmed by one third after flowering is spent. During fall, the plant turns silver-gray and breaks off from the root system at ground level and new growth will emerge in spring.
Baptisia australis has very deep tap roots, therefore it is not recommended to be dug up once established (high risk of losing the plant). Before planting, make sure there is enough room for it to grow to its mature size of 3-5 ft. tall and 3-4 ft. wide. It is very well behaved by not being weedy or invasive.
This bush prefers full sun and needs medium watering until established. Afterwards, it will be drought resistant (because of its deep root system). It should be planted in moist, well-drained clayish, gravely or sandy soil. There is no need to fertilize (it creates its own Nitrogen!) and it is very resistant to pests.
Propagation of Baptisia australis Seeds
Baptista australis can be propagated from stem cuttings in spring when new growth is still relatively soft (late April-May). Roots should emerge in about 8 weeks.
Sow Baptisia australis seeds about 1/2″ deep, outdoors in late fall or spring. If started indoors (or outdoors in spring), the seeds need to be scarified (rubbed between sandpaper). Plant scarified seeds about 1/4″ deep. It helps germination if bottom heat of 75F is provided until seedlings emerge. They will emerge in about 1-2 weeks. We get very good germination if we scratch up the seed coat real good between sandpaper prior to planting.
Buy Butterfly-safe Wild Blue Indigo Plants and Seeds
There are many advantages to making this bush part of your landscape:
-once established, it remains healthy for many years with very minimum maintenance
-beautiful foliage and blue pea-like flowers
-seed pods are very interesting and attractive, useful in dried flowers arrangements
-deer and rabbits ignore it
-no significant insect or disease problems
-could be part of cottage gardens, prairie gardens or meadows
-great companion for our Wild bergamot (Bee Balm)