I use 1/4 to 1/2 strenght of these to mix with vinegar and Epsom salt.

Trace

Odd advice.

Follow the directions on the package. That's how much.

With the hungry Meyer Lemon, however, I find that fertilizing at 1.5 strength during the Summer months is what works best.

Josh

Odd well most instructions are for in ground trees you will kill trees in pots if u go full. But each to his own speaking from experience and learning curb.

Trace

Why would one use an in-ground fertilizer for container trees without specific container application instructions? That just doesn't make sense.

Besides, Foliage Pro and Osmocote (which Steve mentioned) both have container instructions. Further, Foliage Pro is clearly a fertilizer intended for plants in containers. And I know from experience that one can fertilize higher than full strength (which is only 114 ppm N, as is).

Josh

For many years now, for all my potted plants (not only citrus), whatever the fertilizer I use, I only check the EC (electric conductivity), which is the roots "understand". With very good results.

Roots don't "know" anything of brands or fertilizer labels, not even of ppm dissolved. Although, EC is directly proportional to ppm dissolved .

The EC is what measure the easiness of the roots to absorb water and nutrients. For citrus, the maximum recommended is 1.7 dS/m.

Although all elements contribute to increase EC, usually, it is more understandable to manage ppm of N, assuming that once known the NPK ratio, the other elements are found in a proportionate quantity to N.

For citrus, the most recommended NPK ratio, is 3-1-2.

If you fertilize citrus in each watering, the ppm of N recommended is 100 to 150 ppm N.

For a garden fertilizer, with standard NPK ratios, you won't go wrong if you use ppm N as a guide (like Josh says), although it isn't the recommended 3-1-2 ratio.

For example, these are the ppm of N (in red) that Dynagro recommends for Foliage Pro

A strongly recommended reading:

Fertilizing Greenhouse Crops in Alabama

Well, I have to amend the showed in my above Foliage pro label.

I assumed that "tsp" is tablespoon (15 ml), but I was wrong, it is teaspoon (5 ml). By the way, it gave very logical values.

So ppm N are much lower that those I wrote.

The right data are (gotten from here):

Maintenance (every watering): 1 part FP in 3000 parts water (1 ml for 3 Lts water) (30 ppm N)

Production (weekly): 1 part FP in 1500 parts water (1 ml for 1.5 Lts water) (60 ppm N) to 1 part FP in 750 parts water (1 ml for 0.75 Lts water) (120 ppm N).

I am currently astonished, because those ppm N are in my opinion very low for citrus growing.

It is commonly assumed that an optimum N ratio for each watering for citrus are between 100 to 150 ppm N.

Those recommended for Foliage pro are much lower.

I have tested at home the EC of a 100 ppm N of Foliage Pro solution and (with tap water) it is 0.89 dS/m. It is a very safe value, much lower than the maximum recommended for citrus (1.70 dS/m).

It would be perfectly possible to water with each watering in a FP/water ratio of 1:1000 (90 ppm N), and even we would be below the recommended N ratio for citrus.

So here there is something wrong or I am losing anything.

Axier, you make growing citrus in containers sound like rocket science! It's not that complicated.

Thanks for your encouragement Bounty.

It actually IS that complicated if you want to do a nearly perfect job. Most people find that it isn't worth that much work, even engineer types like me. I am very thankful for the fanatics that do the extensive research so that I don't have to work quite so hard.

All of my neighbors say that my citrus is the best they have ever tasted. Over half of them have citrus trees of their own. Foliage Pro, Osmokote Plus, Jack's High Performance, and GroPower Citrus seem like magic to someone that hasn't dug into the details.

im not smart enough to figure all those numbers out but what I am smart enough to do is see how my trees respond. For the last 2-3 years using foliage pro and a slow release I have gotten what i consider slow to medium growth in my trees. That could be contributed to being containerized and that they go into the greenhouse for winter. We do maintain a growing temperature in the greenhouse so the limiting factor would probably just be light.

I have always done 1/2 what the label of the FP says for production per week. going into this year I planned to double what the labels says so 2 tsp per gallon per week and see what happens.

If axier's numbers are correct in all aspects then i hope to see a lot of growth.

mike

9-3-6 time 3 equals 27-9-18. This works great for my Meyer lemon trees and my 2 in ground tangerine trees except my product. miracle grow. I add a table spoon of vinegar to help with nutrient uptake in the winter. I foliar spray much more with a vinegar free solution. Vinegar can be harmful to the leaves.

FP is a fertilizer for foliage plants, if I am not wrong, and the instructions they give I suppose that are for covering the most of plants.

But 30 ppm N (1 tsp/gallon) is a very low dose of N, even if you apply it in each watering. Imagine if you use "half strenght", 15 ppm N is a ridiculous amount of N.

Are your plants healthy? Maybe, but you are not giving the best N amount.

You are not using all the FP potential for your citrus.

Even the most delicated plants receive at least 100 ppm N in each watering.

On the other hand, for example Geraniums, 200 to 300 ppm N.

I am referring to use FP exclusively, if use it with Osmocote, then it is different. You would have to check the substrate EC, and to dose FP accordingly.

FP is designed for using as unique fertilizer, in that case, you don't need to check EC.

How do you measure your conductivity? Do you use a multimeter? How far apart are your probes? How long after watering or fertilizing do you make your measurement. Just curious as this seems like the best way to really determine whats going on w/o guessing or sending away for a soil test.

Best,

~Mick

For measuring EC I have used for years an EC tester, more specifically this one. I am very happy with it.

I use the Pour Thru method, a NC University method which is currently the most used.

I have just acquired the FP fertilizer, I have tested the 100 ppm and 200 ppm N solutions and I now know the EC of them. if I use the same water for it, the EC will be always the same, so it is not necessary to measure it again.

For example, I know that 100 ppm N of FP (aprox. 1 tablespoon/gallon), with my tap water, is 0.89 dS/m. A very safe value for use each watering, with the precaution of a 10 or 20% leachate in each watering to avoid salt build-up in the substrate (in my case, 5-1-1 substrate).

Once I have a fertilizing schedule, I monitor the EC after the first waterings, and for example after a rainy day. To know how the fertilizer regime and substrate combination works.

Once known the above, it will be always, more or less, the same. It is not necessary to be always with the EC meter into the pocket.

From time to time I also check the PH, also with the Pour Thru method and PH strips, cheap and accurate.

I like Osmocote for house plants and ornamentals however I am not sure how it does with pound solids. The time release benefits are very good. I have been using this triple 20 on container citrus and commercial grove. The potassium nitrate will raise pound solids and make fruit sweeter. I don't really need all the N as it makes for elongated fruit so I back it off a bit. Foliar applications are biweekly at first then monthly.