Fill a tall, narrow pot partially with Bonsai potting soil that contains natural materials, which can include pine bark, river sand, calcined clay or peat moss. Trim the roots of your small, young ficus tree. Clip off the lowest branches and branches that occur on the underside of the trunk.
Plant your ficus tree, setting it high enough to prevent it from resting on the lip of your pot or from touching the side. Leave a portion of the roots above the soil at an angle. This will force the tree to grow to one side of the pot rather than upright. Fill the pot with more potting soil, pressing it down with your fingers to stabilize the tree. Place it indoors, in a spot that receives bright, indirect light; it prefers natural sunlight.
Keep the soil of your cascaded ficus tree moist at all times, especially during warm weather. To check soil moisture, insert your finger into the soil about 1 inch deep. This plant can tolerate occasional overwatering as well as dry periods.
Trim new growth as it appears to encourage the downward growth of the plant.