Birch trees are common ornamental trees used in residences throughout North America. They are known for large root systems. Mature birches have root systems that are about one-third the size of a football field. This means birches require lots of water and should be fertilized as well.
Fertilizer is a natural or chemical organic compound that is added to the soil to provide nutrients for plants, such as birch trees.
The Birch Tree Care website does not recommend using lawn fertilizer because it has too much nitrogen. The USDA website states that any lawn or garden fertilizer is adequate as long as it is high in phosphorous.
The University of Saskatchewan website recommends using an acidified evergreen fertilizer such as 30-10-10 because birch trees do better in soil that is slightly acidic.
Fertilizer should be applied in the spring. If the tree is fighting off insects or disease, it can be fertilized periodically through the summer until it goes dormant in the fall.
The USDA recommends 1 lb. of fertilizer per inch of diameter on the tree's trunk. Place it in a series of holes 8 to 10 inches deep that are in concentric circles starting 2 feet from the tree.