To propagate a Kwanzan cherry tree, you can take a cutting from a healthy branch and place it in a moist medium. The best time to do this is in late spring to early summer. 

Steps

  1. Select a branch with 2–4 leaf nodes
  2. Cut a 4–8 inch section of the branch at a horizontal angle 
  3. Remove the leaves from the bottom 2/3 of the cutting 
  4. Dip the cut end of the cutting in rooting hormone 
  5. Place the cutting in a container with a mixture of perlite and peat moss 
  6. Water the cutting and cover it with a plastic bag 
  7. Place the container in a sunny location 
  8. Mist the cutting twice a day to keep the soil moist 
  9. After a few months, check if the cutting has rooted by gently tugging on it 
  10. If the cutting is rooted, transfer it to a larger container with potting soil