Find a basket that will fit around the bottom of your tree stand. My tree stand is 18 inches. My basket is 20 inches. Measure from the ground to the bottom of the tree. You will cut the bottom of basket off at that same size. Use sharp clippers to cut the basket. Be sure to keep the cutting line as even as possible.
Remove the bottom of basket and place under tree. You'll want the handles of the basket to face down. Slide the tree into the basket.
Try customizing your Christmas tree collar by painting it or weaving in colorful yarn or ribbon.