River red birch, known botanically as Betula nigra, is a landscape and timber tree known for its pale coral pink bark that cracks and peels and turns a dark reddish brown hue as it gets older. River red birch is native to the United States and is widely naturalized, following the Mississippi River corridor up through Minnesota. It is tolerant of wet soil but will cope with occasional drought conditions and is hardy in USDA zones 4 though 9.
Fertilize your river red birch tree to speed up growth and establish it in the landscape at planting time, boost soil nutrients if lacking, or maintain vigorous branch growth if it has faltered. Conduct a soil test to determine if fertilizer is required if in any doubt about need.
Select a nitrogen-and-potassium-rich slow-release granular fertilizer formula with a guaranteed analysis of about 10-0-10 with no or very little phosphorus. Slow-release fertilizer will not burn delicate birch roots or the trunk and will reduce the frequency of fertilizer applications, which will also save you some time.
Apply fertilizer twice a year in October or November and again in March or April. Refrain from feeding from August through September to prevent growth that may be damaged by winter cold.
Cast the fertilizer granules over the surface of the soil under the tree canopy, evenly extending a foot or so beyond the drip line of the tree. Follow the product label dosing directions to determine the amount of fertilizer to use.
Water the fertilizer in well to begin to drive the nutrients down into the root zone where the birch tree can make use of them.