Many cassias will re-seed under the parent plant. These seedlings are easily transplanted, so share them with butterfly-enthusiast friends. Nurseries specializing in butterfly plants may have cassias. Plant sales at local botanical gardens and butterfly exhibits may also sell plants. March 31, 1997.
Cassias are fast growing plants.
I prefer this method so there is plenty of food for sulphur caterpillars to enjoy. When used as a landscape plant only, it is recommended to cut them back hard after flowering. Because they tend to be weakly rooted, plant them where it is not windy. They grow in a wide range of soils including alkaline, but prefer very well-drained soil with occasional deep watering. They work well in the background of a large mixed border planting or in front of a dark green shrub-mass.