How to Apply Fertilizer to Trees – A Guide By Horticulturist

So, you got the most popular fertilizer for your tree(s) and realized you don’t have the slightest clue how to apply fertilizer to trees! The first thing that pops up is merely to spread it or spray it around till the last granule/drop.

That would be your first mistake, and believe me, I know it from the experience that almost killed my backyard tree. You can call it a narrow escape, but such errors are to avoid at all costs.

Therefore, it is sensible to start with soil testing. The test result will give you a reading of what is missing and what is adequately available. Then search for fertilizer of that particular or close to the nutrient requirements.

And now, you get to learn how to do the job without over-feeding them.

How to Apply Fertilizer to Trees – The Complete Process


1. Read the Signs

Do not just assume the trees need additional nutrients without determining the comparisons. Are the trees going through stunted growth? Does the color of the leaves turning pale?

How long are the new twigs, and are they growing healthy? These are a few questions one should answer by eliminating the other stresses like drought or flood.

Sometimes there are insects and diseases to consider as well. You have to rule them out, too, since they do not fall in this category. 

2. Fertilizer Type


It is better to collect all the data and test the soil for precise supplement requirements. You can do it by yourself if you have the equipment or send the soil samples to a local lab.

Choosing the fertilizer after checking the results then will become a breezy step. Always select the specifically formulated ones to fulfill the deficiencies. You can also apply the all-purpose fertilizer that shows 10-10-10 ratio analysis.

Now whether you want the granular form or concentrated liquid is up to you. I usually go for the granule packages because I find them super easy to handle and apply.

3. Calculate Root Zone


It is essential to calculate the critical root area to avoid over-usage. Therefore, here is the shortcut to determine how far the zone reaches.

Never forget that tree roots always grow twice as far as the branches spread out. So you will not have to dig into the surroundings to check how far the roots have gone. Simply stand right where the lengthiest branch has ended.

It is from that point you estimate a radius starting from the trunk. Once the difficult part is over, all you have to do is calculate the critical root zone using the radius or diameter distance in feet.

Multiply the root diameter with 3.14 or square root radius with 3.14 to get the final answer.

4. Fertilizer Amount Requirement


The last thing you will have to work on is multiplying the application rate with the root zone to figure out how many pounds of fertilizers you can use.

Suppose it is a 10-10-10 granular bag where each element covers a 10% or 0.1 application rate per 2,000 sq. ft. It is about 2 lbs. in a 20 lbs. bag. 

5. How to Apply Fertilizer


Finally, you get to apply the fertilizer after marking the root zone boundary. Do not consider it a hassle because you can just use a kind of hose pipe as I do.

If you like complete accuracy, I recommend circling the area with a line of flour. You are to mark another circle that is at least 3 or 4 feet apart from the trunk. The distance depends on the size of the tree.

It could be less than 3 feet in the case of small trees. Anyhow, do you see the two concentric circles perfectly drawn up to mark the territory? This is where you apply the fertilizer either in granular or liquid form.

Spread the granules evenly on the ground within the marked region. Water the area afterward.

When using concentrated fertilizer, do not forget to use a garden hose spray to dilute the water. Never apply the liquid without mixing it in the instructed water level.

Best Season to Apply

The best seasons during when you will attain the best results are early autumn or spring. It is at this time of the year roots are prone to grow energetically.

Also, make sure the lawn or the property land is dry prior to the application. Moisten the surface only after distributing the fertilizer. It allows the soil to absorb the micronutrients slowly for the roots to intake.

Final Words

Most information I have endorsed here is from lengthy research and, of course, due to my years’ worth of trials and errors. Some of the application mistakes are inevitable for a beginner.

However, I have written this article to reduce such inaccuracies and keep growing the trees. Let’s hope it encourages you to remain active and care more about what you feed them.

As long as you understand the temperamental shifts, you will know when and what type of fertilizer to implement. All that remains is the question “how,” which has been covered here with easy instructions. Good luck!

Scroll to Top