I saved seedpods from my Baptisia this fall, and wonder about the best way to grow this plant from seed—when to sow, etc.
According to The Gardener’s A-Z Guide to Growing Flowers from Seed to Bloom (Eileen Powell, Storey Publishing, 2004), you can sow directly outdoors in late autumn or early spring at a depth of ¼ inch.
You can also start seed indoors six to eight weeks before the last frost. Germination time varies from 5 to 36 days. Powell recommends soaking the seeds in warm water for 24 hours, and then chipping them with a knife. Keep at 70-75 degrees F once sown. Transplant after the last spring frost, or in early autumn. Baptisia likes full sun to light shade, and well-drained soil. Plants grown from seed may take a couple of years to settle into the garden.
Miriam Goldberger, author of Taming Wildflowers (2014) and proprietor of Wildflower Farm, has additional advice, including an alternate outdoor method of putting sown seeds in potting medium out in late fall to winter to allow natural cold stratification (this applies only if your winters are cold enough!). “The seed will germinate in the pots in spring as the weather warms up. Be sure to water the pots regularly in spring and once the plants are 5 cm (2 inches) tall, transplant them into your garden.”