epsom salts (magnesium), how much?

Discussion in 'Maples' started by emery, Dec 27, 2008.

  1. emery

    emery Renowned Contributor Maple Society 10 Years

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    Normandie, France
    I have several places in my garden where the maples (and also cornus) tend to be a bit chlorotic. So I intend to try some epsom salt and see if it helps. (Epsom salt not being available in France, I have obtained the equivalent from the pharmacy: chlorure de magnesium.)

    I have no idea of the "strength" of the magnesium salts, I assume it is pure as the packets have no other ingredients listed.

    The question is, how much do I sprinkle around on the soil? Does it need to be dug in (awkward around existing plants) or will the water bring it down.

    The big one: can I cause any harm with an overdose?

    Is there a prefered time for the treatment (i.e. is it persistant in the soil) or can I just do it now in winter?


  2. alex66

    alex66 Rising Contributor Maple Society 10 Years

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    ROME Italy zone9/b
    hi Emery i use Sequestrene ,easy available ,in wholesale for garden...
    chloritic with this element is under control ...
    the dose is write on pack...
    i use Sequestrene in February..
    ok your question is about epsom salts,but i not use this sorryyy....
  3. ashizuru

    ashizuru Active Member Maple Society 10 Years

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    Spalding UK
    Hi Emery,

    I use epsom salts at 25g/mtr 2 scattered around the trees, you can work it in the top soil, but the weather usually takes it down into the soil, I do this in late fall or early winter,

  4. emery

    emery Renowned Contributor Maple Society 10 Years

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    Normandie, France
    Thanks Ashizuru, I'll use your formula.

    Meanwhile I hope you are not too affected by the cold. I see the forecast is calling for a very deep drop the night of Tuesday/Wednesday, with -4/-5 even around you. I fear that here in the forest we will see -14C, which is rather a stress for some of my maples. (We already had -9 a few nights ago, and probably colder last night, but I haven't checked to see what the minimum was with my neighbor who measures such things).

  5. ashizuru

    ashizuru Active Member Maple Society 10 Years

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    Spalding UK
    Hi emery,

    We are experiencing snow showers here at present, with a bitter n/e wind, I've been checking my pots with young acres in, 08 seedlings, they were all frozen solid, I have moved them into the glasshouse for a bit of protection,along with my bonsai trees, so hope there will be no permanent damage.

    The rest of the trees seem to be coping ok, the coldest we've had it so far is -5c, we get some protecting influence from the Wash, as we are only a few miles or so from the sea.

    All the best for 09,

  6. Ron B

    Ron B Paragon of Plants 10 Years

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    WA USA (Z8)
    How much, if any to add depends on the chemical makeup of your particular soil.
  7. mr.shep

    mr.shep Well-Known Member 10 Years

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    San Joaquin Valley, California
    For inground Maples a lot depends on
    the age of the tree, soil type, soil pH
    and for a leaf chlorosis, how extensive
    is the condition? Epsom salts can
    be ground applied to help for an Iron
    or more likely in Maples a Manganese
    deficiency. The problem is that some
    Maples, once they are showing severe
    chlorosis symptoms of Manganese
    deficiency, do not readily or cannot
    recover from it. A case in point is
    some of the Shirsawanums in that
    once we see the chlorosis in the
    late Spring to Summer leaves we
    have a hard time ever correcting the
    condition for container grown plants.
    Can be futile to treat for some of
    the inground Shirasawanums as
    well, even in saline soils that have
    some bound salts but not as prevalent
    a salt buildup as an alkaline soil has.
    Even soils that are too acidic can
    be tough to treat for Manganese
    and Iron caused chlorosis. Seldom
    does Magnesium cause a leaf
    chlorosis on Maples, so in effect
    we use Magnesium sulfate to
    cause a substitution reaction
    in our soil to help the plant
    assimilate Iron and Manganese
    to help lesson the chlorotic
    symptoms. We can also use
    Calcium to do the same thing
    but Calcium in acid soils may
    not help solve a chlorosis but
    may in fact make the condition
    worse in some areas. Precisely
    why a soil test is advised prior
    to usage of applied Calcium
    and Magnesium for acid soils.
    We generally are advised to
    treat for a potential or suspected
    later occurring nutrient imbalance
    in Maples prior to planting, rather
    than trying to correct a chlorosis
    after the fact, when we see the
    severity of the condition year
    after year with a noticeable loss
    of vigor seen in the tree.

    For my 15 gallon container Maples
    I use one ounce of Epsom salts
    per three gallons of water. For
    container Citrus the standard
    rate is one tablespoon per gallon
    of lukewarm to warm water. For
    large sized inground Maples I have
    applied as much as a two pounds
    per tree when needed in the early
    Spring and let natural rainfall work
    in, dissolve, the crystals for me.
    In areas that do get ample Winter
    rainfall a late Fall, early Winter,
    application of Epsom salts seems
    to work okay.

    For me here, sprinkling the crystals
    around the tree about two feet away
    from the trunk will just set on the
    ground until we get a series of
    rains to work the dissolute down
    into the ground for me. For our
    large inground Silver Maple I have
    used 2 pounds of Epsom salts
    hand mixed in with 5 pounds of
    Ammonium sulfate as a standard
    application for my tree in alternate
    fertilizing years. Ammonium sulfate
    as a standalone in the other yearly
    Spring applications.


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