Hello everyone,

Newbie here (and to growing fruit trees as well) and need some guidance.

We recently purchased a House with a nice sized backyard. So this is my first stab at growing any fruit trees. This is in California San Francisco Bay Area.

I recently purchased some Orange trees from Costco (From Willits and Newcomb Citrus Nursery http://www.wncitrus.com/)

One is a Washington Navel and the other just says Late Navel (doesn't say which variety it is)

I just finished planting the trees using a 50/50 Compost/Local Soil. The local soil is very silty/sandy - much like beach soil but much more fine grained and slightly better water holding capacity.

The trees are in very good shape and are blooming (were so at Costco itself). When I bought those, they appeared to be water starved as a minor shake in transit would result in a couple of leaves and some bloom buds dropping. But it's been a week now since they have been planted and watered (Twice a week - Deep watering - Only when the top 2" layer of soil is just about drying up) and everything looks fine. New growth is showing up and should pick up some vigor soon.

So with that background - Here are my questions:

#1. Should I fertilize the plants now (Remember that I already did a 50/50 compost/soil mix when planting, though I haven't topped of with compost)?

#2. If so, what fertilizer ratios should I look at for my location/variety?

In the FAQs Joe mentioned a 5-1-3 ratio whereas I think Millet mentioned a Vigoro 12-5-8 (http://www.vigoro.com/ProductCategories/PlantFood/PremiumCitrusAvocadoFood/)

So what's the best ratio for my location/variety? Though I lack knowledge and experience as a gardener; I might be able to pull off a custom mix of good (refined?) individual fertilizers to get the desired ratio with my DIY spirit (am quite Handy around the house - ) and your knowledge and experience.

#3. What brands are considered better brands for fertilizers (I read somewhere that some brands have a better "refining" process than others)

#4 (This bugs me a lot) - Okay we got the ratios - Say 5-1-3 from Joe's psot in the FAQ section. After the "custom" mix, say I end up with a 10LBS blend. But of these 10Lbs, HOW MUCH quantity (by weight/volume and not by ratios) to apply through the year? What's the formula to arrive at the quantity of blend needed? It would be great if we could take the first example in Joe's post in the FAQs section for deriving a 5-1-3 blend.


P.S. I would like to see responses to questions 2, 3, 4 even if I don't need to apply a fertilizer immediately.

Thanks,
Dinesh

dgs,

There are general rules of thumb.

The first one is that, you just calculate the needs of your plant, depending on size, based on the Nitrogen requirements for simplicity, and the reset of the other fertilizer will come proportionately. So you calculate how much weight of nitrogen per unit weight of your blend gets.

Another guideline is that you can fertilizer every time you water if your citrus are not in danger of frost. The one used by UCR is 300 ppm Nitrogen every time they water and they dissolve the fertilizer with water and irrigate with such water all the time, of course, the trees are in the greenhouses. So, if you follow the 5-1-3 ratio, just calculate based on the nitrogen content. This is excellent if you use fertigation drip system. However, I recommend that you cut this down to 200 ppm for the cooler coastal climate, that is just my "guess".

Another guideline you generally apply 1 lb (or approx 2 cups) of 21% nitrogen fertilizer per inch of trunk diameter. That is a whole year's calculation. You would use slightly less because you're in a cooler climate. That means that you apply just about 2.5 to 3 oz of equivalent pure nitrogen per inch of trunk diameter. If your tree is new, I assume it is no more than 1" diameter, so apply less. What is the effective Nitrogen portion of your blend? You can determine it also from the formula. Then you should be able to back calculate in terms of amount of the blend. Whatever your total annual requirement, it is recommended that you apply the fertilizer in splits. The more splits the better. The most common one is to subdivide the application during the active growing season. Of the total requirement apply 1/4 in mid-February to prepare for the coming growth flush and encourage blooming, then 1/8 in mid March then 1/8 each month until mid-August. That should give you the whole thing. Some would split the application further into every two weeks. Or if it was a warmer than usual Fall season, apply more fertilizer when you have no danger of frosts, such is the case of coastal climate.

These are just general guidelines. Sometimes, if your soil is so rich, you can even skip some years fertilizing. A good soil or leaf analysis would be better, but even if the Ag Extension office will do it for free, it still costs money shouldered by taxpayers.

kindly go into your user profile and indicate your location so that many of us can immediately contextualize recommendations.

For new trees, apply fertilizer as soon as you see new growth flushes.

Hi Joe,

Thanks for the response.

I will be honest, it will take a few more reads of the FAQs post and the one from you above to actually get it. The posts are very helpful, it's just that I think I was looking at the various parameters in isolation of each other. I guess I need to bring them all in together to see the light!

Some more info about the plants:
* They are about 3 feet high. New growth (since purchase has been around 4" +/-)
* Between 1" and 1.5" thick
* Planted with root ball in place (After scouring it to free the winding roots). So I believe it will be a while before the new root growth hits the Soil mix with compost and start absorbing nutrients.

Thanks a ton again!

Will update demographics in my profile after I hit submit here.

- Dinesh

I think it is not a good idea to add amendments to the soil when planting citrus trees, especially if the soil does not drain well. The best way to plant a citrus tree is to dig a hole just slightly bigger than the rootball and back fill with the dirt that was removed from the hole. It will help to spread the roots a little as you did.

The exact ratio of nutrients is not as important for in ground trees as it is for container trees. Spread the fertilizer evenly around the tree--keep it at least 6 inches from the trunk for small trees --a ft for larger trees. Spread it about a ft past the canopy for small trees and up to 2 ft past the canopy for larger trees.

for a 1-year old tree apply 0.3-lbs. of *actual Nitrogen per tree per year divided into 6 applications, using a 6-6-6 or an 8-8-8 fertilizer. For a two year old tree apply 0.6-lbs. of actual nitrogen per tree per year divided into 5 applications per year using a 6-6-6 or an 8-8-8 fertilizer. For a three year old tree apply 0.9-lbs. of actual nitrogen per year per tree divided into 4 applications, using a 6-6-6 or a8-8-8 fertilizer. For a four year old tree apply 1-lbs. actual nitrogen per year per year divided into 3 applications per year, using a 6-6-6 or a 8-8-8 fertilizer. Make the fertilizer application between late February and August. NOTE: do not use a fertilizer with a nitrogen percentage greater than 8 percent on a citrus tree younger than 4 years old. - Millet

* Note: this is not pound of actual fertilizer, but pound of actual nitrogen. You will need to calculate pounds of fertilizer depending on the nitrogen percentage of the fertilizer you select.

This equates to:

For 6-6-6 Fertilizer
Year 1 - 0.83-lbs. 6-6-6 fertilizer per each application (6 applications)
Year 2- 2-lbs. 6-6-6 fertilizer per each application (5-applications)
Year 3 - 3.75-lbs. 6-6-6 fertilizer per each application (4-applications)
Year 4 - 5.6-lbs. 6-6-6 fertilizer per each application (3- applications)

For 8-8-8 Fertilizer
Year 1 - 0.63-lbs. 8-8-8 fertilizer per each application (6 applications)
Year 2 - 1.5-lbs. 8-8-8 fertilizer per each application (5 applications)
Year 3 - 2.8-lbs. 8-8-8 fertilizer per each application (4 applications)
Year 4 - 4-lbs. 8-8-8 fertilizer per each application (3 applications.

Millet (These are corrected amounts, see note on my post below)

The general recommendations that I made about using 2 cups of fertilizer per inch diameter are from various Citrus growers in the Bay Area. I certainly apply a little bit more than that as we are hotter inland.

Joe, I did originally post the wrong amounts on my fertilizer above post, but I have changed them to the correct figures. The rates above are now correct. Thanks for noticing.- Millet

Thanks for a much more detailed calculations. I make those same kinds of mistakes often.

Ok. I *think* I got it.

And though Millet's post gives all the exact applications, I still would like to understand the math behind it (Sorry, but feed someone once and his hunger is addressed for a few hours, but teach someone to cook and he can make himself a meal everyday....right? )

So, painful though this might be, please please bear with me here. I will use Millet's example to confirm my understanding. Please point out any misunderstandings.

Assume a 1 Yr Old Tree:

A. Total Nitrogen Requirement Per Yr : 0.38 Lbs (Only way to know the total nitrogen requirement per year is "ask the experts"...right?)

B. Ratio: 6-6-6 (Only way to know the desired ratio for a plant OR individual N/P/K total requirements is "Ask the Experts"...right?)

C. Number of applications ("ask the experts".... right?)

Once A, B and C are known then it's math after that based on product selection and concentration.

So with Millets example:
A = 0.38lbs
B = 6% (Am taking only the N and say I chose a 6% N fertilizer)
C = 6 Even Applications

D: Total Pounds of fertilizer with B N content that would be needed is :
100/B*A which equates to 100/6*0.38 = 5 Lbs Fertilizer (Including the filler)

E: Per Application Weight (including the filler) would be:
D/C which equates to 5/5 = 0.83 Lbs

So is all the above understanding of the math involved correct?

I understand that the units of weight/volume have to be the same across the equation and that if the distribution of applications is not even, then the per application numbers would change.

And if all of the above is correct, then to conclude, the right questions that I should ask in future for other plants would be:
1. How much of total N, total P and total K that specific fruit/variety/for a given age/trunk size needs per year ?
2. And what is the best Application schedule/distribution of total requirement of all these 3 elements for the plant for the year?
3. Once I have the answer to #1 and #2, the ratios don't matter as much (as they are a derivative of the total requirement by application schedule and distribution of the individual elements)....right? OR is there some plant physiology thing that says "such and such ratio is the best for such and such plant", work out the applications based on that ratio?

The rest is the above math as I understood from Millet's example, right?

Thanks a ton everyone for your help. If Millet/Joe could just confirm my understanding of the math and that the 3 questions one should ask around fert req for other trees are the right questions - I would really appreciate it.

Sorry if this was redundant but it's reflective of my struggle with this and my attempts to develop a grasp on some basics.

Thanks again (and sorry if I this was a pain). I really appreciate your taking time to explain this to me and the quick responses.

Cheers:
- Dinesh

Hi Dinesh!

The final answer is correct, but some intermediate steps have minor numeric typos. Here's the proper way to do it if we use Millet' recommendation.

So a 1 year old tree would require 0.3 lbs N per year.

A = Total Nitrogen per year per tree, 0.3 lbs/year
B = % N in the fertilizer, so for a 6-6-6, this is 6%
C = Number of equal applications, let us say 6 even apps
D = Amount per application of fertilizer

D = (100*A/B)/C
= (100%*0.3 lbs/year/6%)/(6 applications/year)

Canceling the units properly should give you
0.83 lb/application which is equal to what you have.

For inground citruses, a complete fertilizer ratio (NPK are equal), you wouldn't worry much about the ratios as long as you satisfy the N requirements. But of course, if we do some nutrition balance, whatever is removed must be replenished, plus allowances for growth storage and leaching. The 5-1-3 ratio would be the best to use even in the inground situation but the soil has large buffering capacity and using the complete fertilizer would be okay for many productive years of your crop, but ultimately, this will become unbalanced and you will have more P in the soil and such conditions could result in thicker rinds and other excess P problems unless the P are always locked away by other minerals.

I would recommend that you buy the Citrus/Avocado fertilizer that have minor nutrients in them, then correct it for the 5-1-3 ratio only if you would like, but using Ammonium sulfate and Sulpomag or KMag. These have been the best fertilizer combos that I have used.

For example, the citrus avocado fertilizer from GreenAll has a ratio that is 14-4-8 which is 7-2-4, close enough for the 5-1-3 ratio that there will be no significant difference if we correct it to be exactly 5-1-3 since we are doing inground application and our major reference is just around the N requirement. Another important factor is to match the tree demand for major nutrients, that is why we should not apply fertilizer when the tree is nearly dormant as the fertilizers would just leach away and pollute the environment. So be proactive in learning the projected growth spurts of your tree in your area. Experience and taking notes will be excellent to guide for your local backyard. Anticipate when these are going to happen and be sure the fertilizers are in the proper depth of the rootzone when the tree needed them most. That is why I follow a skewed split application to time with the rainfall and the onset of frosty nights.

My major decision on what fertilizer to use is whatever goes on sale, and I correct the ratios of whatever on sale items I can get my hands on. My basis of sale is on the price per unit of actual NPK (the fillers excluded).

Should you use the 14-4-8 Citrus avocado fertilizer, you would need to apply:

(100% * 0.3 lbs/year/14%)/(6 apps/year)

=0.36 lbs/application
= 5.7 oz per application of 14-4-8 GreenAll's Citrus/Avocado fertilizer.