Can You Over Fertilize a Tree?

big strong tree growing in field

So, what is fertilization?

Most people tend to follow the thought process that trees are nature and nature will take care of them, meaning, there is no need to worry about feeding, watering, etc. However, when it comes to trees around your home, or special trees that you want to see at the full potential, tree fertilization is something we need to pay special attention. 

Tree fertilization is the process of maintaining trees in according the various conditions they are planted to increase their resistance to diseases, injuries, and insects. The soil is tested to determine the health conditions for any deficiency and then fertilized, as necessary. Read on as we discuss things like how to fertilize a tree and answer common questions about the subject, providing information about tree fertilization and tree health. 

What helps trees grow faster?

The early life stages of a tree are the most important, just like a human. Their lifespan will be determined by the care they are given during the first few seasons. Their shape and how strong they will be are predetermined during those times. It takes a lot of energy for a young tree to establish its roots and with their susceptibility to drought and heat, it requires special attention to tree care by you in maintaining their environment. In addition to tree fertilization, the following are just as important: 

  • Watering: The best irrigation for trees is a deep and slow application of water and a structured schedule. The soil should be damp not soggy and allowed to dry out for a short period so that oxygen can  penetrate the soil. When a structured watering schedule is combined with good mulching routine, the watering becomes more effective. This can be done by spreading natural mulch around the tree as a layer of protection from extreme temperatures and maintain the right moisture content. Mulch helps minimize the tree roots from competing with weeds. 
  • Protection: A young tree needs to be protected from animals, chemicals, equipment, and wind the first five to seven years. Using a tree shelter is similar to a greenhouse type of environment that promotes the growth and is available in various sizes. 
  • Disease Control and Pruning: Lastly, taking care to control and prevent disease along with good pruning practices are important in healthy tree growth. The right timing and tools are important when it comes  to pruning. A constant in tree health is fighting diseases and pests. Inquire with the local Cooperative Extension Service for the particular diseases and insects that may plague your areas. 

Should newly planted trees be fertilized?

As we mentioned earlier, the first few seasons of a new tree fertilization and protection are the most important, and none more important than that first growing season. Use of a high nitrogen fertilizer is absolutely NOT needed. During the growing season, using a root stimulators or half the suggested amount of a slow release organic fertilizer is sufficient. The second growing season use a slow releasing fertilizer three to four times a year, but never should an herbicide containing fertilizer be used near the root system. 

What fertilizer is best for trees?

There are two types of fertilizers: 

  • Fast-release: A water-soluble fertilizer that releases the nutrients quickly and in well-draining soils, like sand,  this fertilizer may move too quickly past the root system, washing away  after a few inches of irrigation or rainfall. In a clay soil, it will leach slower, but the runoff is usually greater.
  • Slow-release: With an extended release of nitrogen, excellent for newly planted trees, or for an area where runoff is highly possible. 

It is recommended to test the soil’s level of phosphorus and potassium, but in general, fertilizer with a count of 12-4-8, 12-6-6 or 16-4-8 offer what trees typically need. 

small tree with fertilizer

How much fertilizer do trees need?

The proportion of fertilizers is indicated on the label, stating the available nutrients and breakdown of the formulations. The following are the general recommendations by experts for application for a tree fertilization program.  

  • Testing of foliage and soil may indicate specific nutrient requirements and those results should be followed. 
  • Best fertilizing time is from late April and no later than early May, for trees that are dormant, fertilizing in late fall is acceptable. Spreading the recommended amount and type of fertilizer evenly across the soil surface with the amount of nitrogen applied at three  pounds per 1,000 square feet. 
  • Do not use fertilizer with herbicides and use a nitrogen content of 12% to 30%, with 3% to 12% phosphorus and potassium. 
  • The application rate of fertilizer should be  based on the root area with roots that are beyond the branches typically at  1.5 times the branch spread’s diameter.

How do you deep fertilize a tree?

Deep root tree fertilization is done by sticking a pipe down into the soil eight to twelve inches deep, and then apply a pressured squirt of fertilizer into the ground. By injecting the fertilizer with pressure through the pipe, the theory is that fertilizer will go in deep where the tree roots are located, getting the “medicine” to the roots. 

Can you over fertilize a tree? 

Absolutely, yes, it is possible to overdo tree fertilization is possible. Applying a high level of quick-release nitrogen will burn tree roots and when applied in a spray, it can burn any foliage.  A fertilizer high in phosphorus or potassium can create excessive soil salts which trees are not always able to tolerate. Need help finding the best fertilizer method for your tree? Call 817-882-6499 today!