Quick Facts about Senna marilandica:
Hardy in USDA zones 4-9
Full sun, part-shade
well-drained, medium moist, drought resistant
Native to central, eastern and southern US
Showy clusters of yellow flowers from mid to late summer
Grows about 4-6 feet tall
Space 2-3 feet apart
Propagated from seed
Maryland Senna in the Butterfly Garden
This senna is a member of the pea family (legume species). It is a pretty plant that is often used as a tall accent in the back of wildflower, native, cottage or butterfly gardens.
As a plant in the butterfly garden it serves to add beauty and provides food for several species of butterfly caterpillars. Cloudless Sulphur, Sleepy Orange, Orange-Barred Sulphur, Tailed Orange, and Little Yellow (Little Sulphur) Butterflies will all use this plant as a host-plant on which to lay their eggs.
This plant has several common names such as Maryland Senna, American Senna, and Wild Senna. Its close relative, Senna herbecarpa, is also commonly referred to as Wild Senna so this can be a point of confusion.
These plants are nearly identical except S. herbecarpa has a native range that extends farther up into the northeast and Canada than Maryland Senna and not as deep in the south. The range of the two Senna’s overlap heavily in the mid eastern states. The easiest way to tell the difference is that S. marilandica’s dried seed pods stay together in the fall while S. herbecarpa’s seed pods burst and expel their seeds once dry.
Maryland Senna used to have the name of Cassia marilandica before it was changed to the now proper name of Senna marilandica.
Germination of Senna marilandica Seeds
These seeds can be fall or winter sown with no pretreatment necessary. The cold wet conditions will take care of preparing the seed for germination. However, if you are starting this seed in the spring then the recommended method for preparation is to lightly scarify the seed followed by 2 weeks of cold/moist stratification.
Scarification can be accomplished by lightly rubbing the seeds between medium grit sandpaper. Cold/moist stratification is simply placing the seeds in moist sand, vermiculite, or a moist paper towel in a plastic bag in the refrigerator for 2 weeks.
After treatment, the seeds should be planted, lightly covered with soil, and kept moist at room temperature. They will take anywhere from 1-12 weeks to germinate.
Why Try Senna marilandica?
Not all host plants are also pretty garden plants. However, this trouble-free, native, wildflower not only provides beauty in the garden but also feeds 5 different species of butterfly caterpillars. That’s a superb, multi-tasking, butterfly-garden plant!