Cloning Justica californica from stem cuttings

Question

We are a nature education center trying to propagate Chuparosa from stem cuttings. We currently cut the stems about 3-4 inches high, remove all but the terminal leaves, dip the freshly cut stems in rooting hormone, place the cuttings in cells with potting soil, and put them inside a small terrarium (21.2 x 11 x 9.5 inches) with a heat pad underneath (set to 70 degrees). We have tried keeping them humid as well as a little drier, but are still struggling to get them to root before rotting.

Should we let the cutting “heal” for a day or two before we place it in rooting hormone? Do you think they may be too humid? Should we cut them taller than 3-4 inches? We also plan to start using a greenhouse during the rooting process, so they will only be in our terrariums for a few days. Any advice would be greatly appreciated!

Answer 1

Use a half soil/half sand mixture for the cuttings.
Place the cutting in a moderate sun location. Early spring or late summer is the best time to take the soft cuttings.

https://www.gardeningknowhow.com/ornamental/shrubs/chuparosa/chuparosa-plant-information.htm