Time Frame

• One reason that your magnolia is not blooming is that it simply may not be old enough yet. According to the Christian Science Monitor, it can take magnolia trees 15 to 20 years to bloom for the first time.
  
  

Nutrients

• A lack of vital micronutrients can also prevent your magnolia from blooming, according This Old House. Soil that is rich in nitrogen but lacking in phosphorus may encourage the growth of the tree, but may be preventing your magnolia from blooming.
  
  

Pests

• Some pests will also stop your magnolia tree from producing flowers. If your trees develops buds that do not open, it could be thrips, insects that attack and kill developing buds, according to the University of Florida. Flowers infested by thrips may open but fall off prematurely.