Citrus in alkaline soil

jenn(SoCal 9/19)June 22, 2011

I've read here that citrus like acid soil. Our house is built on a former citrus grove, and our tangerine tree has done marvelously well for decades.

Yet, our soil is alkaline (confirmed by our sizzling-HOT PINK Hydrangea). My mom's soil is acidic and sandy (blue hydrangea, thriving Azaleas and Camellias) and her house is also on a former citrus grove (many years ago) yet her citrus trees don't appear any happier than ours in alkaline clay.

Our Brunfelsia (likes acid soil, I'm told) is happy as a clam (fed with cottonseed meal several years ago but not since) yet the acid-loving Azaleas (long gone) failed to thrive.

I'm curious about these inconsistencies and wonder if anyone can explain them.

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It is commonly written on this forum that citrus are an acid loving plant. Actually this not correct. Citrus like a soil with a pH of 6.5 which definitely does not qualify the citrus tree as an acid loving tree. In fact a vast amount of the worlds plants prefer a 6.5 pH. Blue Berries, Azaleas, Heath, Holly, Camilla and the such are acid loving plants with pH of 3-4. A pH of 6.5 is about as close to natural as one can get.

    Bookmark   June 23, 2011 at 6:28PM
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redshirtcat(6a MO StL)

"The Biology of Citrus" by Spiegel-Roy and Goldschmidt suggests a mildly acidic soil pH of 6.0-7.0. They note that you may obtain "satisfactory results up to a pH 8.0 or even somewhat higher." pg 148

They note earlier in the book that the poncirus trifoliata rootstock (dwarfing) is less tolerant of higher soil pH and high alkalinity/salt content. (chart on pg 129)

I've read in other places online that citrus prefer 5.5-6.5. The University of Florida extension site suggests 6.0-7.0 (

I acidify my tap water to around 5.5 because I read that the pH will rise as dissolved CO2 escapes. Hopefully this puts my soiless mixtures somewhere around a pH of 6 - or on the acidic side of what citrus prefer as that's what I've read flying dragon rootstock likes.

Silica I've seen you post authoritatively a few times. I'm not criticizing but I'd like to know if you're in the business or what your credentials are so as to better judge your advice (if that makes sense). It's just that when sources disagree I like to know what everyone's experience is and etc. I'm just a backyard grower etc.

    Bookmark   June 23, 2011 at 7:52PM
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This is a VERY interesting thread.

It makes perfect sense in my case. With my faucet water at a pH of 8.0 and higher, my trees do lousy until I add vinegar which lowers it to a range of 6.0-7.0

I can tell you too that the rain water that falls here registers at 6.5 and sometimes lower, and my trees explode with vibrancy once I get drenching rains!

Being one that has years of experience with fish tanks, I can tell you that the pH of municiple water around these parts is way to akaline to keep any fish alive unless the pH is lowered, not by vinegar of

Thanks everyone


    Bookmark   June 24, 2011 at 10:01AM
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I affirm what Redshirtcat has posted from the two sources.

    Bookmark   June 24, 2011 at 12:41PM
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jenn(SoCal 9/19)

Thank you for the very interesting responses!

We have not (yet) had any formal soil testing done, but we know our soil is alkaline ---- we just don't know how alkaline, nor the pH of our water. It sounds like many of you have a home kit to do random pH tests. Where could I find a good one?

    Bookmark   June 24, 2011 at 2:55PM
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mksmth zone 6b Tulsa Oklahoma(6b)


you can get PH test kits from anywhere that sells pools or fish supplies.

dont use strips they are inaccurate.


    Bookmark   June 24, 2011 at 3:01PM
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As for water:

I already have test kits for that. I got mine at a fish store for 10 bucks. It is vital for all living things in my pond and tanks:-)

I think that I can get a soil test kit at a nursery or hardware store. I have seen them there. I am not sure how accurate the cheaper ones are as compared to the higher end more expensive ones though..I saw one for 200 dollars!


    Bookmark   June 24, 2011 at 3:11PM
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Jenn, you didn't state specifically what kind of tree you have: tangerine is typically used for the Dancy mandarin, but some use it generically for any type of mandarin.

If your tree "has done marvelously well for decades" there is no reason to change the anything. But to help, you can use an occasional dose of an acid-loving fert, or alternatively something like Dr. Iron (iron+sulfur combination) to slightly lower your already alkaline soil.

If you do measure your water pH, just realize that pH alone without the alkalinity measurement (to determine "buffering ability") can be of limited help. You can search the container forum for 'pH' to find some more info.

As mentioned above, rootstock selection is a factor in how well the tree will perform under alkaline (and salt) conditions. Here is a section from a narrative presented at a UCCE Kern Citrus Growers meeting in 2005 regarding Mandarins (specifically satsumas) by Craig Kallsen, Citrus, Subtropical Horticulture, Pistachios Advisor.

Most citrus in the southern San Joaquin Valley are planted on Carrizo rootstock which appears not to excel in any particular characteristic but performs fairly well in most. Unfortunately, Owari Satsuma mandarins are, often, not long lived if planted on Carrizo or its close relative, Troyer, rootstocks [due to rootstock overgrowth/benching]. Both Carrizo and Troyer are citrange rootstocks, which mean that they are the result of a cross between a selection of sweet orange and a trifoliate orange. [C-35 and C-32 are also Citrange rootstocks.] ...
(mandarin) fruit quality on trifoliate rootstocks is very good, but the trees grow slowly and yields, especially in the early producing years of the orchard, are usually significantly less on a trifoliate compared to a citrange. Trifoliate rootstocks are more resistant to Phytophthora root rots and freeze damage than the citranges, but trifoliate is intolerant of alkaline soils. Depending on other soil properties and fertility, even a neutral pH can cause growth problems with most citrus species grafted on trifoliate rootstocks. The C-35 citrange, like the trifoliates, also demonstrates poorer growth in alkaline soils. For orchards with alkaline soil, the Cleopatra mandarin rootstock might be a possibility. Like trifoliate rootstocks, initial yields are low, but fruit quality is good, and the trees will be longer lived than with the citranges. Cleopatra mandarin, although salt-tolerant by citrus standards, would not be suitable for poorly drained soils as it is susceptible to Phytophthora root rots. Lemon type rootstocks, such as rough lemon and Volkameriana, produce fast tree growth and high yields, have few graft incompatibility problems and are tolerant of alkaline soil, but fruit quality is poor. Satsuma fruit from trees on lemon-type rootstocks is usually not as sweet or as juicy as that on trifoliate or the citrange rootstocks. Lemon rootstocks are very susceptible to root rots. There appears to be no acceptable rootstock for Satsuma mandarins for orchards with heavy, poorly-drained alkaline soils."

In the CA Master Gardeners guidebook, page 550, the table of Rootstocks used in California Soils shows "Poor" for Trifoliate Orange on alkaline soils.

    Bookmark   June 25, 2011 at 6:10AM
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jenn(SoCal 9/19)

So interesting -- thank you! I've learned more in these forums than in all the gardening books I own.

My husband doesn't remember the name of the Tangerine we own; it's been here since he moved here in the late 60s and planted it along with a dwarf lemon. A few years ago, the lemon suddenly took a nosedive and didn't recover, so we unfortunately had to remove it --- after years of thriving in that spot, we're still wondering why, but perhaps the encroaching perennials near its drip did it in. :(

    Bookmark   June 25, 2011 at 11:22AM
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If it was the 60s, the fruit ripens around Christmas, has seeds, and have a deep orange color... it's probably a Dancy.

RE the lemon: From what I'm told by several folks (though I have yet to find it documented) is that Eureka lemons are not productive much past 20 years. This would be crop potential -- as far as true life span I have no idea. Also, some trees back then were on rootstocks that did not have the virus/disease protection that are commonplace now.

    Bookmark   June 25, 2011 at 8:59PM
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