Inspect the agapanthus for dead or diseased branches. Remove them before you prepare it for the winter.
Determine whether your agapanthus is deciduous or evergreen. Each one has different steps for proper care.
Move the deciduous agapanthus to a dark cellar or garage right before the first frost. When it has gone dormant if you live in zones lower than seven. The proper area should remain around 41 degrees Fahrenheit.
Withhold watering during the winter dormancy period. This can waterlog the roots causing them to rot.
Store the evergreen agapanthus in a cool light place. Almost any area will work such as an unheated hallway or entrances as long as it is draft free.
Provide a cup of water each month to the evergreen agapanthus. This replenishes the plant with water loss due to evaporation.
Apply a 4 inch layer of mulch over the top of the ground. This will help insulate them against freezing.