From sunny St Petersburg, Florida
warm day, I took cuttings from 10 crown of thorns. dipped cuttings in warm water to stop the sap. allowed the cuttings to callus for 30 hours in a cool dry and dark place.
I planted all cuttings in a Miracle Grow cacti potting soil, in a wooden wine crate with drainage holes. watered in, and three days from potting the cuttings are dropping their leaves, (not all but most). The cuttings are in full sun- 8 hours. temperatures have been hi-70s, low-50s.
why are they dropping their leaves and is this okay?
Thank you for contacting Toronto Master Gardeners. The Crown of Thorns or Euphorbia milii is a Madagascar native. It is a woody, multi-stemmed, succulent shrub. It blooms abundantly through the spring and summer but can also bloom throughout the year. It is very drought tolerant and easy to grow. The sap from the plant which is toxic causes skin irritation so it’s important to wear gloves when providing care. The cuttings need at least 2 to 3 leaves to propagate. Allowing the cuttings to callus in a dark place and planting them in cactus potting soil are good steps. Some other factors you might consider for successful propagation include the following:
• Cuttings are more successfully rooted when they are taken in spring and summer.
• It helps to dip the cuttings in rooting hormone.
• One source suggests that you need to keep the cuttings at a consistent temperature of 75 degrees F.
• There isn’t a consensus about the light requirements for the cuttings but several sources suggest that you should keep the cuttings in shade rather than direct sunlight while rooting.
Below are some sites where you can read more about the propagation of crown of thorns plants:
https://www.houseplant411.com/houseplant/crown-of-thorns-plant-how-to-grow-care-euphorbia-milii
https://homeguides.sfgate.com/caring-crown-thorns-cactus-28422.html
https://www.thegardenhelper.com/crownofthorns.htm
Finally there is a Master Gardener group in Florida that responds to enquiries for that area:
https://www.facebook.com/florida.mastergardeners/
Good luck with your crown of thorns cuttings.