I learned somewhere that citrus can handle 1 fruit for every 42 leaves. Another thing to consider is the frequency of being fertilized while growing in a pot. Citrus put a lot of energy into growing fruit so getting fertilizer is very important. Are you fertilizing monthly?

Your branches are really long and lanky looking. When the fruit has been harvested, you may want to cut them back a bit to encourage a fuller canopy.

Brian

Can you suggest a fertilizer for us.Everyone here seams to insist on foliage pro. I am using Miracle Gro 24-8-16 and add 20-0-10 to get a 5-1-3 ratio. My 20-0-10 has 1% iron.

Steve

Thanks Brian

Brian, can you provide a reference for the effect of temperature on root function that you mentioned above? My recollection is that citrus roots go dormant below 55 F, not 65F. Also, where did you get the rule of thumb re 7F?

Brian, none of the fertilizers you recommend have NPK ratio of 5:1:3 recommended by many old time container citrus growers.

Commercial bagged soil mixes are always adjusted to be near neutral.

So it looks like you tend to rely on fertilizers that the manufacturer claims to be suitable for Citrus. So here is a list of NPK (ignoring other components) for your list of citrus fertilizer:

Arizona Best Citrus fertilizer: 13-10-4

Jacks Classic Citrus FeED: 20-10-20

BGI citrus gain: 8-3-9

GroScript RBF Trivium: 18-5-10 slow release fertilizer

Dynamite Palm and Citrus: 13-5-11

Espoma Citrus Tone: 5-2-6

As you see the ratios are all over the map. Seems they cannot decide what is good. How do you reconcile all the differences and how do you trust any of them is actually suitable?

Phosphorus is needed in small quantities. Excessive will cause iron and zinc deficiency even if they are there in the soil and host of other problems. It does not leach out easily either and so any unused P accumulates in soil. Even flushing will not remove it easily.

It is also generally agreed that most backyard soil already has a good amount of P and in a lot of cases excess of it due to excessive use of so called 'balanced fertilizer'. Anyway let us stick to containers since most here are talking about container growing only.

Regarding Arizona's Citrus fertilizer: Great they want to adapt to alkaline soil of SouthWest. Then why not use DPTA chelated iron instead of Iron Sucrate? Why give instructions for container fertilizing? Why recommend a water soluble (not slow release) only three times a year? The plants will get their biggest dose at the time of application and quickly it will dilute and they will get hardly anything in a few weeks. The mobile ions will leach away.

Regarding CEC. Look at the last column in your table where the unit is volume. And peat and bark are the same CEC per unit volume - that is what matters. Bark will slowly decompose and CEC will increase. If you want more CEC throw in turface instead of perlite or peat. Turface is clay based and will increase CEC. Per unit volume it will beat both peat and bark. It will also increase water retention without compromising air porosity. You have to pay attention to oxygen too - the forgotten macro-nutrient.

I was not recommending slow release fertilizers. My point was that the instructions on that fertilizer amounts to binge feeding. Feast or famine. Second, you can always bump up a slow release fertilizer if you want to feed more. Or you could apply say monthly depending on their growth cycle. So I do not buy that quote from the Citrus guy. May be the quote can make more sense in context.

No matter which fertilizer you prefer, if you want to increase say nitrogen availability you just have to bump up the quantity. But you would also bump up everything else it contains by the same fraction. If there is a lot of say Phosphorus in the fertilizer then it will increase that too whether it can be utilized or not. The excess will either remain in soil (if it happens to be less mobile like P and to some extent K) or leach away (like N, Mg, etc). In a container situation, that is mostly devoid of any nutrition source, the ratio of the nutrients in fertilizer is the key. In soil one has to first know the nutrient profile first through a soil test and adjust the fertilizer accordingly. In either case one has to know the ideal ratio that must be provided. I am not going into the ideal ratio because it opens a can of worm. Nevertheless it is widely agreed that N > K > P.

There are two types of slow release fertilizers: one which dissolve slowly (like Shake n Feed) and the other like Osmocote are temperature dependent. The release profiles of these two are very different. There are other problems with temperature dependent release types in container culture.

Regarding CEC you seem to quote some text that basically corroborates what I said. That volume is the important factor and by volume it does not make any difference between 100% peat or 100% bark according to your table. Larger bark pieces will have smaller surface area so it effectively reduce the surface area (for cation exchange) available to the roots. But at the same time increases air porosity.

CEC affects Ca, Mg, K, and Na uptake primarily and secondary it includes Iron and few other cations. High CEC soil can hold on to ammonium ion (only cation that has nitrogen) for a short time (less than 4 days) before it converts to nitrate which is an anion. So it has very insignificant impact on nitrogen holding capacity in the long term. So how does high CEC help for citrus that happens to love nitrogen the most?

Wow -- what happened here? All comments by Lemon/Lime and some from me too got wiped out. Now I have two left above completely out of context. It is possible Lemon/Lime deleted his comments but I did not. Any idea how this can happen other than Houzz censoring?

Tropicfancer, all one has to do is 'red flag' another and Houzz will take it away. Then many will run when questioned or asked to particpate in a conersion and delete theior posts making the one ferring to their comments look foolish, as if talking to themselves. I will tell you that what you had to add is very nice and thank you. Makes sense to me

Mike

Looks like my comments are all back and so I guess it could have been one of many Houzz glitches. In fact, the forums behave differently depending on the browser too. Anyway, looks like Lemon/Lime decided to delete all his posts leaving all those orphaned comments. I am going to leave them as it is. I thought that was a good debate that can be useful to many to make up their own mind. I guess it does not always work with everybody.