Soil
These deep rooted perennials require freely draining soil, but will tolerate clay, loam, or sandy substrate as long as drainage is sufficient and there is no standing water.
While it doesn’t require high fertility, false indigo will grow faster and bloom more abundantly in soil that contains some organic matter.
Water
During the first year, keep the soil moderately moist to help the root system become established.
After that, these plants are highly drought tolerant and typically require no supplemental water unless conditions are extremely dry.
Fertilizer
Resist the urge to fertilize false indigo. Unless you’re growing in very poor, sandy soils, these plants will not need any additional feeding.
If you notice poor growth, you can top dress with several inches of well-rotted manure or compost in spring and fall.
Cultivars to Select
Blue false indigo (B. australis) is the species most commonly found at nurseries and garden centers.
This species is a reliable bloomer with deep blue spires and tops out at four feet tall and wide.
You can find plants available in #1 containers at Nature Hills Nursery.
There are a few cultivated varieties worth seeking out, including:
Lemon Meringue
‘Lemon Meringue’ is a yellow-flowering Baptisia hybrid that’s part of the Decadence® series. The lemon-colored blooms are held on three-feet-tall, charcoal colored stems.
This dense and compact cultivar is especially vigorous and floriferous.
You can find ‘Lemon Meringue’ plants available at Nature Hills Nursery.
Twilite Prairieblues
Twilite Prairieblues™ is a B. australis cultivar, bred by the Chicago Botanic Garden. It’s more dense and bushy than the species and grows up to five feet tall and wide.
In season, it’s covered with purple and yellow bicolored flowers. You will sometimes see this one listed as ‘Twilight Prairieblues’ or ‘Twilight Prairie Blues.’
You can find plants available at Burpee.
Maintenance
Once established, false indigo requires absolutely no maintenance except for occasional watering during dry spells.
After flowering, allow the spent blooms to turn into beautiful, dark seed pods and don’t be tempted to prune dead stems back until new growth emerges in spring.
Many beneficial insectsincluding native bees use dead stems as shelter through winter, and the charcoal colored pods add texture to the off-season garden.
Propagation
There are two primary ways to get false indigo started in your home garden, one harder than the other.
You can either start from seed, which takes time and isn’t always very easy or reliable, or you can purchase nursery starts for transplanting.
Let’s discuss each:
From Seed
Seed can be harvested in the summer when the seed pods are dark, firm, and starting to split open.
If you collect seed, you’ll need to cold-stratify it for at least eight weeks before sowing.
You can do this either by sowing in flats and leaving them outside for the winter or putting them in the fridge in a zip-top bag with some moist vermiculite.
To let nature do the cold stratification for you, fill a flat with moistened potting soil and sow the seeds just below the surface. Place the flat outside in a brightly lit, sheltered location.
Ideally, the seeds will stay consistently cold all winter long, so keep them away from any south-facing walls that may raise the temperature too much on sunny days.
Ensure the soil stays moist, but not soaking wet. If it freezes, that’s fine, when warmth and longer days arrive, the seeds will germinate.
