I was about to buy some Growmore today when I noticed the info on the
pack stated "Westland Growmore is not recommended for use on
ericaceous/lime-hating/acid-loving plants." A closer look at the pack
info did not reveal the contents, and neither did Westland's website
(www.gardenhealth.com). A link there
(https://www.gardenhealth.com/uploads/files/Data_Sheets/150062.pdf)
led to the "Safety Data Sheet", but that too failed to reveal the contents.

So I then googled "growmore msds", and the second hit was to
https://tpprod.blob.core.windows.net/sys-master-tpprodcontainer/hd1/h2a/8859706327070/189483.pdf.
This was also a "Safety Data Sheet", but that one included possible
ingredients, one of which was calcium nitrate, and "inert fillers such
as ... limestone. That, I suppose, was the reason to avoid its use on
ericaceous plants.

What is odd is that the first "Safety Data Sheet" had an emergency
telephone number ()0870...) for the UK. The second "Safety Data Sheet"
just gave a telephone contact number of 0288... (also in the UK, as it
was prefaced 0044). Both the data sheets stated that Westland
Horticulture Ltd in County Tyrone was the manufacturer.

I wonder why there were two data sheets, ostensibly both for use in the
UK, but differing in their information? I must say that in the past I
rarely had a use for Growmore, or any other fertiliser. However, a large
beech tree in my neighbour's garden seems to be sapping whatever
goodness is in the soil in my garden near to the tree. Plants survive -
if watered - but don't exactly thrive. Clematis in particular seem to
have a very hard time. So I reckoned a sprinkling of a general
fertiliser would be a simple thing to try and might help. But as I have
some rhodos and a leucothöe growing there, it isn't /that/ simple!

--

Jeff

In article ,
Chris Hogg wrote:

Can't help you with the MSDS question, but as to adding calcium
nitrate and limestone, I was always under the impression that it's
high pH caused by lime or limestone that's the problem with ericaceous
plants, not the calcium per se. One of my books on rhodos advocates
gypsum as a soil improver for rhodos and azaleas. Proper mineral
gypsum (not the plaster of Paris commonly available from builders'
merchants these days), is naturally slightly acidic, being the salt of
a weakish base and a strong acid.

That's not the reason. There is some reason that magnesium behaves
very differently from most metals, and its salts cause what is
effectively acidity. It's not just totting up the strengths, but
I don't know the details. The effect is also used in brewing.


Regards,
Nick Maclaren.

On 27/12/17 21:17, Chris Hogg wrote:
On Wed, 27 Dec 2017 20:19:16 -0000 (UTC), (Nick
Maclaren) wrote:

In article ,
Chris Hogg wrote:

Can't help you with the MSDS question, but as to adding calcium
nitrate and limestone, I was always under the impression that it's
high pH caused by lime or limestone that's the problem with ericaceous
plants, not the calcium per se. One of my books on rhodos advocates
gypsum as a soil improver for rhodos and azaleas. Proper mineral
gypsum (not the plaster of Paris commonly available from builders'
merchants these days), is naturally slightly acidic, being the salt of
a weakish base and a strong acid.

That's not the reason. There is some reason that magnesium behaves
very differently from most metals, and its salts cause what is
effectively acidity. It's not just totting up the strengths, but
I don't know the details. The effect is also used in brewing.


Regards,
Nick Maclaren.

Er...what I gave was a simple explanation.

The acidity of a salt of a weak base and a strong acid arises because
the weak base is only partially ionised in water. For example, gypsum,
calcium sulphate, dissolves in water (slightly) to give calcium ions
and sulphate ions. CaSO4 - Ca++ + SO4--.

But some of the calcium ions hydrolyse and form an equilibrium with
calcium hydroxide, as calcium is a weak base
Ca++ + 2H2O - Ca(OH)2 + 2H+

The Ca(OH)2 is un-ionised, so contributes neither acidity nor
alkalinity to the solution.

The overall equation when gypsum dissolves in water is
CaSO4 + 2H2O - Ca(OH)2 + 2H+ + SO4-- which has an excess of hydrogen
ions, i.e. is slightly acidic with a pH below 7.

The reverse occurs with a weak acid and strong base, such as sodium
carbonate; the acid is only partially ionised, resulting in an excess
of hydroxyl ions, a deficiency of hydrogen ions and a pH above 7.

The same equations could be written for magnesium, ammonium or any
weak base, but the degrees of hydrolysis will be different, as will
the resulting pH.

Strong bases, such as sodium or potassium, don't hydrolyse, so their
solutions remain neutral.

All good stuff, but after reading a bit about the problem calcifuges
have with calcium I'm even more confused!

From what I understand, the problem results from poor availability of
intracellular phosphate, in particular iron phosphate. Now just what
causes that is what confuses me. Sure, you could say that calcium reacts
with phosphate to form a pretty insoluble form of phosphate, and that's
the reason.

But calcium carbonate (as limestone) is pretty insoluble in water too,
and even though the solution is alkaline (pH around 8), how much of that
calcium is available to "mop up" phosphate? Now calcium nitrate is
extremely soluble in water, but the pH of a 5% solution is around 6. So
(like gypsum), does that pH prevent problems with calcium even though
there is so much more of it in solution?

Oh, on the msds question, I see that the date of the "uninformative" one
is a lot more recent (2012) than the one which lists the contents
(2004). Progress, eh?

--

Jeff

On 29/12/17 19:17, Chris Hogg wrote:
On Thu, 28 Dec 2017 09:18:18 +0000, Jeff Layman

I've just been into a Wyevale garden centre, and they stock Miracle-Gro
Growmore instead of Westland Growmore. Intriguingly, there is no mention
on the label of avoiding its use where there are ericaceous plants! It's
still a 7-7-7 mixture.

So far I haven't been able to find what its ingredients are - not even
an msds. I assume they don't use limestone as a filler.

--

Jeff