Extremely difficult to root, I'm sorry to report. The best thing is to bend canes down and partially cover with soil. Come back a year later and a portion of them will have good roots, and will be ready to detach. Softwood cuttings during the growing season are nearly impossible.

Thank you, Paul. Do you have any idea why it is so hard to root?

Because its a spinosissima! That whole clan can be very difficult to propagate from cuttings. Why, precisely, I do not know. Try the layering approach, as I suggested. I have actually produced extra plants of 'Suzanne' quite easily that way.