Topic: Gypsum

[hopalong]

I want to get a few bags of gypsum to break down the heavy clay soil in some parts of my allotment that are so far not developed. I'll be adding lots of organic matter too, of course.

Does any one know a good place to get some gypsum? I am not keen to get it from a builders' merchant as their gypsum may have other stuff in it that could be harmful for gardening purposes. I'm looking for  an outlet that supplies it specifically for gardening.

I gather that, according to the Henry Doubleday Research Association, gypsum is acceptable for organic gardening. It's a good source of calcium sulphate and can be added without altering the soild pH if you don't use too much of it.

Thanks in advance for your help.

[Tee Gee]

I want to get a few bags of gypsum to break down the heavy clay soil  I'll be adding lots of organic matter too, of course.

Whatever you do do not put them on at the same time.

This link might help you;http://www.thegardenersalmanac.co.uk/Data/Soil-Liming/Soil-Liming.htm

I am not keen to get it from a builders' merchant as their gypsum may have other stuff in it that could be harmful for gardening purposes. I'm looking for  an outlet that supplies it specifically for gardening.

What makes you think there is 'other stuff' in it?

Its either gypsum or it is not  ???

You will probably pay two-three times for 'gardening specific' stuff and it might well have been sourced from the same spot.

I use 'Hydrated lime'

From experience at B&Q I bought 55kg Kiln dried sand out of the 'building' section for £1-99 and similar stuff in the 'gardening' section was nearlry £3 for 5 kg. So I guess lime/gypsum will be similar.

Guess what I bought?  yes !! the cheap stuff and it was perfect for what I wanted it for.

But at the end of the day the choice is yours.

[hopalong]

Many thanks for the advice Tee Gee.  Incidentally, the warning about gypsum came from an old booklet of mine on vegetable growing by Roy Hay, a highly respected gardener, written in the 70s.  Quote: "Be sure to obtain straight gypsum from a garden shop - gypsum from a builder's merchant as used for plastering contains other unsuitable materials". I don't know what materials he meant, but that is what he said.

[Mr Smith]

Having worked for British Gypsum in the past there are several types of gypsum which all do different a job when applied, you are correct in saying that the finished product in the builders merchants does have additived and is not pure gypsum.

[Tee Gee]

you are correct in saying that the finished product in the builders merchants does have additived and is not pure gypsum.

Mmmm!! I should have thought of that, now that I think about it there could be, for instance, retardants to slow the setting process down.

I stand corrected,so you see I am human and I don't get it right every time  ::)

Great medium is the internet, there always seems to be someone who from their own experience can keep people in the picture. Thanks Mr Smith.

But I still think I was on a winner with the sand ;)

[hopalong]

Thanks Tee Gee. I'll certainly follow your advice on sand -  in fact, I did the same thing myself at B & Q a while ago and my plants suffered no ill effects.

The more I see of posts on this (great) site, the more it seems that there isn't a single right answer to almost any question.

[springs]

dig in pea gravel it wont break down but help with drainage. i also leave as many stones in the ground for the same purpose.