Adding fertilizer can promote healthy root systems, foliage growth, and enhance flower production and color. However, it must be done correctly or you may do more harm than good.

There are 17 elements needed for normal tree growth. Carbon, hydrogen, and oxygen are delivered by the air and water. Nitrogen, potassium, magnesium, calcium, phosphorous, and sulfur are the macronutrients, and iron, zinc, molybdenum, manganese, boron, copper, cobalt, and chlorine are the trace elements. The nutrients most likely to limit plant growth are nitrogen (N), phosphorus (P), and potassium (K). We find these elements in most commercially available fertilizer products with the content shown in the form (N-P-K), where the values represent the amount of each element in the package.

Phosphorus and Potassium elements build root system strength while Nitrogen transfers that energy up to the tree. Newly planted trees have a weakened root system shouldn't be given much nitrogen. If you feel you need to fertilize your new trees, use low rates of a product heavier in Phosphorus and Potassium. After the first year the root system has progressed and is much more able to push development on the top side during the growing season. More nitrogen can start being used.

As the tree grows larger a "drip line" can be established. When this drip line exceeds 2 feet out from the base, fertilizer applications should be at the drip line to promote outward root growth. Use a root feeder to apply the additives to promote that outward growth deeper in the soil.

Trees work on their root systems during winter dormancy. Fall nitrogen applications may promote new branch growth. This is not desired because green branches will freeze and die. Larger doses of Nitrogen should be given shortly before and during the Spring and early Summer growing periods. The general rules to remember:

• Fall and early Winter - More Phosphorus and Potassium
• Late Winter, Spring, and early Summer - More Nitrogen
• First year trees should not be fertilized

The Tree I.V. root feeder is an easy method for delivering fertilizers. The open top reservoir allows you to simply pour in the proper amount of nutrients during a normal watering. We recommend Professor Green brand liquid fertilizer products for all tree applications. 

Our goal is to provide products and knowledge that will work for all varieties of trees. Specific issues in specific environments should be taken to your local arborist. Always follow product recommendations.