All about plant fertilization

Best fertilizer for orange trees [How and when to fertilize]


The sweet orange (Citrus sinensis (L.) Osbeck) is a citrus native to Asian countries in the Rutaceae family. It is also one of the species of the citrus group of greatest economic and nutritional importance. The fruit of the orange tree, the orange, has numerous properties. Rich in vitamin C, flavonoids and essential oils. One of the aspects that most affects orange yield is nutrition, hence the importance of knowing how to apply fertilizer for orange trees.


In this article we will be in charge of studying in depth the fertilization of this popular citrus. What are the most recommended fertilizers, how to fertilize and when to do it. In addition, in the last section we will give you some tips on how fertilization varies depending on the area where you live.

Best fertilizer for Orange trees

1. Orange tree fertilizer requirements


As you must already know, plants need certain nutrients in order to survive, depending on the type of plant, these needs change. In the case of orange trees, they need certain amounts of nitrogen, phosphorus, potassium and calcium. In addition to some microelements such as iron, boron, magnesium, aluminum, manganese, zinc and copper.

The lack or excess of any of these nutrients or microelements entails certain symptoms and discomfort in the orange tree. For example, the lack of nitrogen slowly decreases the vegetation and causes the yellowing of the tree’s foliage, premature defoliation and decreased production. While the lack of iron is manifested as a chlorosis in leaves due to the loss of pigmentation caused by the decrease in the chlorophyll content in the chloroplasts.

The nutrient requirements in the orange tree will not be the same in all stages of the life of the plant. But they will change as the years go by. Thus, fertilization procedures should also change as the plant ages. But do not worry, we will talk about all this in the following sections.

2. What are NPK values?


So that we are speaking in the same language, and when we talk about fertilizers they can understand me, I need us to develop the concept of NPK values. If you have read other articles on this blog, you will have seen that I always repeat it, and it is something quite technical that I need to make clear. If you are clear about the NPK values, you can skip this section. 😉

NPK values are three numbers in charge of indicating the concentration of nutrients in a fertilizer. And those nutrients are the following:

  • Nitrogen (N): favors the growth of the aerial part of the vegetables (leaves, stems). It is partly responsible for the green color of plants and gives them resistance to pests.
  • Phosphorus (P): it is very important in the maturation of flowers, seeds and fruits. It participates in the formation and development of roots and has an important role in resistance to drought.
  • Potassium (K): it is determinant in the development of the entire plant, it allows the roots and stems to be strong and the seeds, fruits and leaves to be large. It provides resistance to pests and diseases, helps the circulation of other nutrients around the plant, and regulates plant functions.

To make it clearer let’s look at a simple example:

If you have a fertilizer with NPK values 10-20-5, it means that 10% of the total weight is nitrogen, 20% phosphorus and 5% potassium. In general, the rest of the total weight is completed with other nutrients and additives from the fertilizer itself.

3. Best fertilizer for orange trees


Knowing the nutrient requirements of an orange plant, it is possible to make a list of the best fertilizers. To make this list clearer, we have divided them between commercial fertilizers and organic fertilizers.

If you are reading this post, you will probably be interested in learning about fertilizing these other plants.

3.1 Organic fertilizer for orange trees

Among the homemade fertilizers that can be most useful for fertilizing oranges we can list the following. Note that many of them are homemade, which will be very easy for you to do yourself. 😉

  • Ground Coffee/Eggshells: Coffee grounds and eggshells are nutritious for plants. The eggshells provide the soil with the calcium it needs, while the coffee grounds provide potassium, phosphorus and nitrogen.
  • Compost: Add compost to the soil around the citrus tree to add other nutrients. Spread about two inches of compost, but keep it two inches from the stem to avoid damage. Take advantage of organic waste from your home to prepare compost.
  • Worm humus: along with compost, worm humus is one of the best ways to increase the quality of the soil for these citrus fruits.
  • How to add iron: Search the market for iron chelates, an inexpensive product that will have a very positive impact on your lemon tree. It will be enough to bury them near the tree and water so that the iron is released.
  • Zinc contribution: Bury a can of any soft drink and moisten the soil. When it corrodes, it will release the necessary zinc for the plant.
  • Fish food: Fish food is about 10 percent nitrogen, so you should add 4 ½ kilos of fishmeal to get about 500 g of nitrogen.
  • Seaweed: Dissolve 1 ½ teaspoons of seaweed powder in 1 gallon of water and spray citrus trees from leaves to drip lines.

These are seven of the best organic and homemade fertilizers for an orange tree.

3.2 Commercial fertilizer

Although it is good to use organic fertilizers, and if they are homemade better, if you want faster results in general it is better to opt for commercial fertilizers. But you can’t buy just any fertilizer, you should look for special fertilizers for citrus:

  • Jobe’s Organics: it is an organic granulated fertilizer, fast-acting fertilizer for fruit and citrus trees; established and new trees.
  • Miracle-Gro Fruit & Citrus Plant Food Spikes: This spiked fertilizer promotes more fruit and lush foliage. Contains natural ingredients, it is necessary to apply it once a season in spring and autumn.
  • BGI Fertilizers Citrusgain Bag: Citrus like orange, lemon, lime, avocado, mango, other fruit trees and plants need ample amounts of nitrogen, potassium, magnesium, manganese, iron, copper, zinc, sulfur, other macronutrients and micronutrients to produce strong growth.

I only selected three commercial fertilizers, but you can imagine that there are many more. In this case, look for some of the ones that are in the Amazon store so that you can advise them.

4. When to fertilize orange trees


Citrus such as Naranjo absorb nutrients in all the times of the year. But it is particularly during spring when they need them most, coinciding with the sprouting, flowering and curd of the fruit.

During spring it is when we have more nitrogen applications. This is why protein synthesis and is part of chlorophyll, influencing a better tree growth and higher fruit quality.

Keep how nitrogen deficit generates yellow leaves and smaller fruits. While if you exed in the contribution of nitrogen there will be a vigor excess that decreases production and its quality, in addition to favoring pests and diseases.

On the other hand during the fruit maturation period you must also contribute these nutrients:

  • Phosphorus (P): to metabolize sugars and nucleic acids.
  • Potassium (K): to stabilize the performance that increases nitrogen.
  • Vital sulfur (S): to synthesize proteins. Its absence has similar consequences to those of nitrogen.
  • Calcium (Ca): for the union of plants molecules and for nutrient absorption.
  • Magnesium (Mg): to generate chlorophyll.

5. How to fertilize orange trees


We have already seen what are the nutrient requirements, what type of fertilizers use and when is the best time to apply them. Let’s see now step by step how you should perform orange fertilization:

  1. Determine the age of the plant: young and growing plants require more nutrients than mature plants. This to increase your growth. For this reason, they will need more nutrients.
  2. Evaluate the nutritional needs of the plant: As we have already mentioned, they need nitrogen, phosphorus and potassium to grow healthy. In addition, other nutrients such as calcium, magnesium and iron also need. To create a fertilization plan, the ideal is to analyze the soil to know the nutrients they have and know which should be provided to a greater or lesser extent.
  3. Choose the appropriate type of fertilizer: On this website we recommend a mixed use between organic fertilizers and commercial chemical fertilizers. You can opt for organic fertilizer such as compost at the beginning of spring, and then if you want to see better results, you can apply some commercial fertilizers during the fruit season.
  4. Apply fertilizer: When using an organic fertilizer such as compost or earthworm humus, you must extend a uniform layer around the base of the plant and mix gently with the earth. When what is applied is the commercial fertilizer, follow the instructions in the package to determine the amount of fertilizer you need and how to apply it. In general, it must distribute it around the base of the plant and then water it to help the fertilizer mix with the ground.
  5. Keep the irrigation plant: after the application of the fertilizer, it must be irrigated quite frequently, since orange plants absorb soil nutrients much better in the presence of water. Be sure to keep the plant well watered throughout the fertilization process.
  6. Repeat the process: orange plants must regularly fertilize to grow strong and healthy. If you use organic fertilizers, you can repeat the process every 2-3 months. If you use commercial fertilizers, follow the package instructions to determine the appropriate frequency.

This is a standard procedure, then your experience, evidence and errors will make the best way to fertilize your orange. The area where the climate, the orange variety, the availability of fertilizers, the characteristics of the soil, among other factors, will make the fertilization procedure change.

If you are reading this post, you will probably be interested in learning about fertilizing these other plants.

6. Extra information


In general, many people ask us when their orange must be fertilized in the area where I live. The places where we have received more consultations are California, Arizona and Florida. Let’s analyze each case very quickly.

Note that to answer these three consultations we will only analyze the differences of climates between one region and others.

6.1 When to fertilize orange trees in california

Starting with California, the optimal moment to fertilize an orange is during the active growth season, which is generally from spring and to summer.

The climate mostly Mediterranean and winter rains provide enough water and nutrients for orange during the cold season. It is for this reason that it is not recommended to fertilize during these months of the year.

6.2 When to fertilize orange trees in Arizona

Arizona is a state with warmer and more dry temperatures than Californa, so the orange growth season is usually longer.

Given these climatic characteristics, it is recommended to fertilize the orange twice a year: once in spring and again in autumn. However, autumn fertilization should be done before the first frost arrives.

6.3 When to fertilize orange trees in Florida

In the case of Florida, the warm and humid climate causes Naranjo to have a longer active growth season than in California or Arizona.

Before this climate, it is recommended to fertilize orange three or four times a year during the active growth season. This growth season can last from the beginning of spring to half of the fall.

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