I have had success with simply throwing a bag full of leaves on top of the clump.

iowa, what's better is that you can cut down the basjoo and wrap the stalk with old dry bath towels. Pin the towels after wrapping to get them to stay on the stalk. Then get some containers or something to hold insulative stuff such as leaves or straw and put that around the towels. Finally get some plastic tarp and lay that on top to keep out rain and snow. Don't forget to use something heavy like bricks to hold down the plastic.

Bradleyo, Do you mean that you dump the leaves from the bag onto the clump? Or do you just put a closed bag of leaves on top of the clump?? I am confused. Also, what zone are you in? That might work for me if I am in the same zone.