How to make a hanging basket. 1  Place a layer of the wool or moss in the bottom of the basket as a liner and bring it up the sides. 2  You'll need quite a thick layer to provide the support the plants need.3  Give all the plants a good watering before starting. Place a layer of the wool or moss in the bottom of the basket as a liner and bring it up the sides. 2  You'll need quite a thick layer to provide the support the plants need. 3  Give all the plants a good watering before starting. 4  Cut a circle from a compost bag for the basket bottom, to help retain water.