If you want to try this, how about visiting Kosetsuen Park,
This year, they don't give cherry twigs at Goryokaku Park. When I visited there on March 5th, pruners were pruning cherry trees and beside them there were signs saying "Please keep away from pruners and this year they don't give you cherry twigs."
When I visited Mt. Hakodate last month, they were pruning cherry trees near the parking space near the gate of the mountain road;)