The Trick to Growing Multi-Stemmed Baptisia

Jeremy Windemuller

Baptisia is one of the longest-lived and most carefree native perennials available today. However, since it has a relatively short bloom window, we recommend staggering planting dates by 2 to 3 weeks to have plants in color over a longer period. Retailers should plan to feature these plants prominently when they’re in bloom to move them out quickly. A large picture tag will help them to sell when they’re no longer flowering.

Potting and timing
Through several years of trials, we’ve learned that the best way to grow the highest quality finished baptisia is by starting with 72-ct plugs, planting one plug per 2-gal. pot from late May to mid-June in Zone 5 and growing them outdoors. Alternatively, you can plant one 72-ct plug per premium 1-gal. pot by early July. Bury the crown slightly below the soil line, covering up to two nodes on the stems to encourage eye development below the soil line.

Baptisia may also be started from bare root, planting one root per premium 1-gal. to 2-gal. pot in fall or early spring (recommended). Bury the crown slightly below the soil line just as if growing from plugs (see above). Grow these plants indoors at a cool growing temperature of 55 to 60F (12 to 15C) and hold them at 40 to 50F (4 to 10C) when finished. Allow for 8 to 12 weeks finishing time in premium 1-gal. pots or 10 to 14 weeks in 2-gal. pots.

Whether starting with plugs or bare root material, use a well-drained soil mix composed of bark and peat with a pH of 5.8 to 6.5.

Vernalization
Baptisia requires vernalization to bloom to achieve its mature upright habit and to produce multiple stems per pot. Bare root plants purchased in spring will already have been vernalized. 72-ct plugs started the summer prior will need to go through an 8 to 10 week vernalization in order to have blooming plants the following spring.

Cultural recommendations
Fertility
Well-established plants in the landscape are quite self-sufficient, as baptisia is considered to be a legume and, therefore, has nodules on its roots to harness Nitrogen naturally from the earth. In production, they’re moderate feeders. Use 75 to 125 ppm Nitrogen constant liquid feed at every watering or incorporate slow-release fertilizer at a rate of 1.25 lbs. per cubic yard of growing media. The recommended EC rate is 2.0 to 3.0 using the pour-through method.

Moisture
Native baptisia is very drought tolerant in the landscape due to its extremely long taproot. In production, more water is needed. Keep plants consistently moist during the bulking stage. Once a good root system is established, they can be grown a bit drier. Drip irrigation is highly recommended with baptisia because the large canopy of foliage blocks overhead water. It’s also beneficial to keep the foliage dry.

Lighting
Baptisia is daylength neutral and doesn’t require artificial lighting to flower. However, high light levels are recommended during the growing season—this is a full-sun plant. Grow this crop under clear plastic indoors or in direct sunlight outdoors.

Growing temperature
Grow baptisia indoors from bare root at 55 to 60F (12 to 15C) or grow them outdoors from 72-ct plugs under natural temperatures in summer. Don’t force plants to bloom in spring under warm temperatures or it will cause them to stretch excessively and quickly become overgrown. Forcing under cool 50 to 60F (10 to 15C) temperatures results in more compact and desirable finished plants.

Overwintering
Baptisia is a very hardy perennial. The best way to overwinter them is in a minimally heated greenhouse kept slightly above freezing. However, they may also be overwintered outdoors under a heavy frost blanket or in an unheated greenhouse. Bait liberally for rodents over the winter and don’t let plants sit wet or crown and root rots may settle in.

Pests and diseases
This native perennial is quite pest and disease resistant when grown properly. Improper watering practices may lead to powdery mildew, root rot and defoliation. Use drip irrigation to avoid such issues.

Spacing
Baptisia grows very large in production. It’s critical to space them well to grow well-rounded, uniform finished plants. Good spacing also allows for better airflow, which prevents foliar diseases.

Pinching
DO NOT PINCH baptisia once they’ve been vernalized! Doing so will likely eliminate flower production that year. Also, don’t deadhead spent blooms as that’ll remove what will become decorative seed pods in the fall. However, when growing finished plants from 72-ct plugs the summer prior, it’s appropriate to shear the plants back by half in midsummer to create a fuller habit. Since those plants won’t be sold until the following spring, you won’t have to worry about eliminating those flowers.

PGRs
The Decadence series of baptisias are naturally more compact and shorter, so they may not require PGRs when grown under proper conditions. Most other types will require some PGRs to make them more manageable in shipping, especially if they’re grown too warm. Drench plants with 6 to 10 ppm Bonzi when they’re 6 in. tall to control plant height. Drench rates will vary widely depending on your soil mix. Spray applications of 30 to 45 ppm Bonzi are also affective, but will have to be applied multiple times. GT

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Jeremy Windemuller is a grower and trial manager for Walters Gardens, Inc. in Zeeland, Michigan.