Hi,

I read many topics on fertilizing citrus trees, you have given information before.
It is obvious that we will go for the 5-1-3 ratio for our container citrus and I see that for 1-2 years old citrus, the best is 1-1-1 ratio like 6-6-6 or 8-8-8 fertilizers.

Now I have questions;

1. After germinating seeds, I transfer the seedlings to 8L. plastic bags until they become 2 years old.And when they are 2 years old, I transfer them to ground.
When I first read about 5-1-3 for containers, I thought these plastic bags are counted as containers and I am giving my trees 5-1-3 ratio fertilizer.

Is this right, because they are all younger than 2 years old?

I need to add that all the trees are quite happy and no sign of any fertilizer burn.

2. When they become 2 years old and I plant them inground, do I need to convert to 1-1-1 ratio ?

3. Last but more important, how about older trees inground? I have older trees inground and wonder what is the best ratio to feed them, still 5-1-3 or what?

Thanks alot, I think this is one of the most important subject, you already gave too much information.

Hi Meyer,
The reason for the 5-1-3 ratio for container citrus is that is the ratio that citrus uses. If you use a different ratio, part of the fertilizer remains unused and contributes to salt build-up-- a problem in container citrus culture. In the ground, the excess P and K will just percolate down into the soil or bind with minerals in the soil. In general the balanced fertilizers are cheaper and work just fine for inground citrus. It would not hurt the tree to use 5-1-3 fertilizer for inground citrus, it would just cost more.

A 4 yr old or older tree inground should be fertilized with about one pound of actual N per year divided into 3 applications. Therefore, if using 8-8-8, you should apply about 4 pounds each application for a total of 12 pounds a yr. That would be equivalent to 1 pound N per yr.

Younger inground trees should be fertilized more frequently, but with less at each application.

Container fertilization should be made according to the size of the container, not the size of the tree.

A citrus tree, whether it is growing in a container or planted in the ground, absorbs nutrients in the ratio of 5 parts nitrogen, 1 part phosphorous, and 3 parts potassium (5-1-3 ratio). The loss of minerals varies greatly in relation to the amount of production, soil, climate, and agricultural practices. As reported by Dugo and Di Giacomo in their study of citrus grown in the Mediterranean countries, they found that a yearly loss of the main fertilizer elements per hectare, in mature orchards producing 30 tons of fruit, was as follows: N=180-220kg; P2O5=30-40kg; K2O=90-120kg ( 5-1-3 ratio). These are, of course, the amounts per hectare of nutrients that must be replaced by yearly fertilizing where there is a satisfactory presence of elements in leaves. There are many commercial fertilizers and they should be chosen according to the replacing of minerals, and the ratio 5-1-3 is the ratio of the main elements lost from a citrus grove. However, fertilizing citrus trees growing in the ground is much less critical than a tree spending years confined to a small space such as a container. Fertilizers such as 6-6-6, 8-8-8 or 10-10-10 are commercially available and are inexpensive to purchase, thus are economical to the field grower. Field grown trees are not as fussy about the fertilizers used as are container trees, because of the vast amount of soil involved, less organic content in soils, and the leaching and combining of elements. Fertilizer ions are absorbed and held by the organic matter present in the soil, until they are released to the citrus tree's root system through the exchange of a hydrogen ion for the nutrient ion. Generally, soil contains approximately only two percent organic matter, where as the artificial growth mediums used in containers can be 90 to 95 percent organic matter. Therefore, in containers any excess nutrition, with the possible exception of water soluble nitrogen, and to a lesser degree potassium, are tightly held by the organic medium, and any excess that is not used by the tree is held by the organic matter and builds up to toxic levels. For this reason the feeding of a containerized tree needs to be kept as close as possible to the ratio of nutrients used by the tree. Ideally, the 5-1-3 ratio needs be held, even in the field. According to the excellent research as reported in "The Genus Citrus" 5-1-3 needs to be respected even in field grown trees. Obviously, in cases of over dosage or deficiency of one or more elements this ratio must be changed to a more appropriate one. Complex fertilizers such as 6-6-6 and others can become problematic, since their ratio does not always correspond to the needs of the orchard. But as always, commercially, everything is a blend of economics and theory. - Millet

Dear Skeeter and Millet,

Now it is all clear, so if we can balance the economic side, 5-1-3 is always the main ratio.The Dugo and Di Giacomo example tells it all and following Skeeter's reccomendation, fertilizing with about one pound of actual N per year is clear.

Skeeter, you wrote it is divided into 3 applications.I think I remember Millet once mentioned that in the university, they apply 300ppm N with every watering;

Quote:

mature citrus trees, the seedling rootstock, along with the diseased citrus are all fertilized at a rate of 300 PPM nitrogen with each and every watering.

Have you tried both and noticed a difference?

I'm sure that supplying the N in dissolved form at the concentration that supports maximum growth will work better than granular fertilizer applied to the soil. If you have to do that manually for a number of trees, that is a lot of work. If you have a system that does that automatically then it actually saves labor. There are many commercial producers that have such systems, but it is not practical for most homeowners.

Thanks Skeeter

What I actually meant is that I wonder if 3 main fertilizing or lots of small amount fertilizing is best?

I have a drip watering system that allows me use special fertilizers for drip systems.So I can try both and I hope I will have a chance to try both next season adn compare.But I will be pleased to hear if you can compare 2 types of fertilizing schedule.

Best

When Skeet is talking about fertilizing 3 times a year, I believe he is talking about in ground trees. The University of California fertilizer rate of 300 PPM is for their containerized trees. According to the University of Florida Institute of Food and Agricultural Sciences (IFAS) the recommendation for trees planted in the ground is 6 times a year for a 1 year old tree, 5 times a year for a 2 year old tree, 4 times for a 3 year old tree, then 3 times a year for each year after that. The IFAS recommends applications up to 0.3, 0.6 and 1-lb. nitrogen per tree during years 1,2 and 3 respectively. Thereafter increase the amount of nitrogen applied according to tree growth, up to but not more than 1.5-lbs. actual nitrogen per tree per year. An example for a 1 year old tree planted in the ground would be 2.5 - 5-lbs. 6-6-6 or 1.8 - 3.8-lbs. of 8-8-8 fertilizers applied 6 times a year. For a two year old tree planted in the ground apply 5 - 10-lbs. for a fertilizer with the formula of 6-6-6 or 3.8-7.5-lbs. of 8-8-8 fertilizer 5 times a year. For their complete recommendation you can send me a private message is you are interested. - Millet

Thanks Millet, that reply clears it now