greetings,

I'm new to citrus growing and the CGF. Great site. Thanks again to those of you that I’ve already inflicted myself upon with PMs.

I was wondering where I can find the suggested fertilizer application rates for containerized trees of various ages/sizes. I’ve had 2 citrus trees for about 3 years each. The soil in each was compacted so I recently switched to a Turface 2/3 and Bark 1/3 mixture. This mixture is VERY fast draining. I hope that it doesn’t drain too fast for the hot temps of the Sacramento area.

As for fertilizing, I've been following Vigoro's directions by applying the fertilizer at 1/2 the rate of in-ground trees. I believe that I've been underfertilizing. I've applied approximately 3/4 of a cup of fertilizer per year (3 x 1/4 cup applications) of Vigoro's Citrus Fertilizer with minors 10-4-10 (I think Vigoro's current formulation is 12-5-8).

The leaves on the trees are consistently a pale green. I figure I can use more N and plan to supplement with some Ammonium Sulfate or just more of the Vigoro. Assuming that I am thinking about application rates correctly (which is a big IF), then I think I can safely apply at least a 1/2 cup 3 times a year. According to Vigoro 1/2 cup of fertilizer weights about a 1/4 lb. So, the .75 lbs of fertilizer will provide about .075 lbs of actual nitrogen. Is this about the right amount?

Any suggestions? Thanks.

-dean

You are following a fertilizer program that is intended for fertilizing citrus trees that are planted in the ground. Your tree is a containerized tree and will need to be fertilized much more often and an a different rate. I would fertilize the tree at least once every month at 250 PPM (Parts Per Million) nitrogen. For a fertilizer with the formula 10-4-10 250 PPM would be 10 grams (1/3 OZ.) fertilizer per gallon of water.

Millet
Carl Linnaeus 1707 - 1778
300th Anniversary Of His Birth

I would also wonder, If your soil mixture is THAT fast draining and the heat in Sacramento is that high. You will be watering ALOT more and may be washing the ferts. out that much faster.
Just my two cents worth.
Darren

Because roots in a container are confined to a very limited volume of growth medium, the quantity of available water is a key factor affecting plant growth. A growth medium that holds large quantities of water is generally very poorly aerated. By contrast a growth medium that is extremely well drained and holds very little water is well aerated but must be watered too frequently to be practical. Frequent watering quickly leaches out most of the nutrients, especially nitrogen and potassium. In general, the most productive container growth media are combinations of components, some that hold large quantities of water, while others hold very little. This creates an assortment of large pores for good aeration while maintaining a reasonable quantity of water to allow for a manageable irrigation schedule.

Millet
Carl Linnaeus 1707-1774
300th Anniversary Of His Birth

thanks for the input Millet. I'll give those amounts a try and see how things go.

Can you share how you came up with your recommendation (250 ppm)? Is this amount a general recommendation for containerized trees? Or, is this based on the age of the trees? thanks.

250 PPM is a common rate of application for many types of containerized plants. Any variation can be used. For example you can apply the 250 PPM at one time, once a month, or you could perhaps apply 100 PPM every time you water the tree. Actually, I prefer to fertilize my trees with Osmocote Slow Release Fertilizer. Osmocote fertilizers slowly releases various amounts of fertilizer with every watering based upon temperature. Therefore, Osmocote releases more nutrients during the summer and less in the fall and winter.

Millet
Lewis Albert Hakes April 16, 1874

Bob when you say 250 at once, do you spread it on top of the medium or dissolve it in water and apply all at once. I also use a little slow release fert. but i think the formulation is wrong it is 19-6-12 should the phosphorous be lower?

Valencia, 19-6-12 Osmocote (3-1- 2 ratio) is not a bad formula. However, it does not contain any trace elements, so you will have to supply them yourself. Remember most fertilizers and trace element packages do not contain magnesium. As far as your question about the 250 PPM, it is usually applied as a dissolved soluble fertilizer, except, of course, in the case of Osmocote and other slow release fertilizers, which are placed on the surface. I always scratch my Osmocote evenly into the soil, so that it does not all run to one spot when watering he tree.

Millet
Anthony von Leeuwenhoek 1632 - 1723

So since I would need to add a trace element mix like S.T.E.M., could i just add it to the water i use for them so every time i water they get the traces?

The best I have found is Vigoro. I am not sure if it is available in Canada.

http://www.vigoro.com/ProductCategories/PlantFood/PremiumCitrusAvocadoFood/ProductLabels/default.htm

hi Laaz,
Do you follow Vigoro's instructions for container use? Or, do you apply at a different rate? thanks.

zymurgist most of my stuff is in the ground. I don't follow any certain regiment on my container citrus though. I throw a handful in every two months or so. Most of my container citrus is in either 5 gal or 7 gal containers. I also flush the containers well before giving them another dose.

Vigoro does contain all the minors as well. But I do still add Epsom salt once a year as well.

zymurgist from your post above it may be that your soil was holding too much water. No matter what fertilizer rate you use, if the roots are waterlogged the leaves will become a very light green to yellow.

Laaz, I see Vigoro's 12-5-8 fertilizer is a slow release fertilizer. There are not a lot of slow release fertilizers on the market that contain trace minerals. Vigoro would not be a bad fertilizer to use for in the ground citrus. I remember quite a while back Dr. Manners posting that in ground citrus trees really are not all that fussy about what fertilizer they receive. Most in ground citrus trees in Florida are fertilizer with 8-8-8 or 10-10-10. Valenciaguy, you could dissolve trace minerals in water and apply to the potting soil once every 3 - 4 months. Trace minerals become tied up with the organic matter in the potting mix and are slowly released as the medium degrades.

Millet
Antony von Leeuwenhoek 1632 -1723