How to Fertilize a Tree

You might be wondering how to fertilize a tree. This article will teach you how to fertilize a tree using inorganic fertilizers, phosphorus, and spikes. Once you know how to fertilize a tree, you can use this knowledge to grow a healthy, beautiful tree. Just be sure to follow the instructions on the container. Moreover, you must know the correct multiplication factor when fertilizing a tree.

Inorganic fertilizers

Organic and inorganic fertilizers together have positive effects on the growth of fruit trees. Both organic and inorganic fertilizers increase the leaf area and net photosynthetic rates. They also increase leaf concentrations of N, P, and K. The effects of organic and inorganic fertilizers are not mutually exclusive, as the results of both treatments are similar. Organic fertilizers also improve the fruit quality and yield.

The most common inorganic fertilizers used on trees are ammonia and calcium. While both are essential for healthy trees, inorganic fertilizers can cause a salt burn if used too frequently. Inorganic fertilizers should never be over-applied, and their salt index should measure their application rate. The risk of salt burn is much lower with organic fertilizers. Organic fertilizers are more effective in improving the health of trees.

When to fertilize trees

If you’re not sure when to fertilize trees, it’s a good idea to research what types of fertilizers your species of tree needs. The fertilizer you use will depend on the size of the tree’s root zone and how much of it you need to apply. You can determine how much fertilizer you need by calculating the trunk’s diameter at 4.5 feet above the soil. Then multiply this measurement by one or two to get a radius close to the base of the trunk.

For most trees, the root zone is the area occupied by the roots. This area surrounding the tree’s trunk extends 1.5 times the distance to the drip line. Mineral-absorbing roots can grow up to four feet beyond the drip line. If you’re not sure how much fertilizer to apply, consider visiting the local county extension office to learn about the specific fertilizer for your species. You can use Milorganite fertilizer in a circular band around the drip line. You can also mix it with the soil at the bottom of the planting hole. Repeat the process three months later.


Fertilizer spikes are a convenient way to provide your tree with the nutrients it needs without the hassle of applying them manually. Instead, drive them into the ground at about two inches below the soil’s surface. Be sure to keep the spike caps for future use. These devices are designed to drive into the ground, promoting the roots to grow towards fertilizer. Then, apply the fertilizer as recommended on the package.

Unlike the usual granular fertilizer, spikes are a light formula with balanced N-P-K ratios, making them famous for ornamental evergreens and other non-flowering trees. Always do soil testing before applying any fertilizer to your tree, so you can determine its nutrient needs and select the right spike. Typically, you will need to use three to four spikes, one for every three feet.


One method to use when fertilizing a tree is by drilling holes. To avoid damaging your turf, mark the holes with twine or string. Drill holes at least three feet away from the tree trunk, and make sure that they are at least one inch apart. Then, fill them with the phosphorus fertilizer and water them thoroughly. Afterward, rake the mulch away from the roots.

When applying fertilizer, use a general-purpose formula that contains nitrogen, phosphorus, potassium, and trace nutrients. Nitrogen is essential for healthy growth and stems, while phosphorus encourages healthy flowering. When fertilizing trees, use a balanced formula with 15 parts nitrogen and 15 parts phosphorus. Do not use too much nitrogen, as too much will burn your tree. Be sure to read the label to see how much fertilizer you should use.

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