Has anyone tried using Gypsum?

[tucker85]

Has anyone experimented with Gypsum as a source of calcium and sulfur? If so, what were your impressions?

[Orchid Whisperer]

Hi Tucker.

I do this all the time. The gypsum that I use is the pelleted kind used for lawns. The pellets have a binder that hold the pellets together, so I put about a teaspoon of pellets in a gallon of water, allow that to sit at least overnight (a couple days is better). I then strain out the solids, keep the liquid and add several ounces of the liquid when I water, at least monthly. I often add a teaspoon of Epsom salts too.

It seems to work quite well as an effective Ca supplement and also provides S (and Mg if you also use Epsom salts).

I have not tried it yet, but plaster of Paris is essentially gypsum that has had the water driven off by calcining. Not to be confused with "lime plaster" which is hydrated lime and sand. Next time I buy "gypsum", I will buy plaster of Paris instead. There is a well-known story regarding Benjamin Franklin who became familiar with the agricultural benefits of plaster while he was stationed in France. Upon his return, he could not convince his neighbors of the agricultural benefits of plaster until he spread plaster in the form of letters in a wheat field, spelling out "this land is plastered" (or something similar - can't recall the exact wording). The wheat grew best where the plaster was applied in the form of letters, and were easily read by his neighbors.

[tucker85]

Thanks for the information, Orchid Whisperer. I just used Gypsum on my plants for the first time this morning. Since I use a calcium/magnesium supplement instead of Epsom Salt, I realized my plants might not be getting enough sulfur. Sulfur is one of the three secondary nutrients along with calcium and magnesium. I'm planning to use it once a month for now and see how it works. I feel better about it now that I know I'm not the only one using it.

[Optimist]

People who are not familier with plaster of paris need to be warned that the exothermic reaction caused when rehydrating is hot enough to burn the skin, and people have lost limbs using it. I tend to wonder about the story of Ben Franklin because of this. The heat would have killed any plant under it.

Personally, I would go to a health food store and get human grade tablets, as calcium, magnesium, and sulpher are needed by human beings too. Is there no bioavailability type issue?

Egg shells also contain these ingredients and can be pulverized in a coffee grinder. I prefer using egg powdered egg shells in the garden and on plants.

[Orchid Whisperer]

Originally Posted by Optimist

People who are not familier with plaster of paris need to be warned that the exothermic reaction caused when rehydrating is hot enough to burn the skin, and people have lost limbs using it. I tend to wonder about the story of Ben Franklin because of this. The heat would have killed any plant under it.

Personally, I would go to a health food store and get human grade tablets, as calcium, magnesium, and sulpher are needed by human beings too. Is there no bioavailability type issue?

Egg shells also contain these ingredients and can be pulverized in a coffee gringer. I prefer using egg powdered egg shells in the garden and on plants.

I am not recommending people apply plaster directly to plants. If that was not clear, I hope to clear that up now. I was strictly talking about making a SOLUTION of gypsum (or plaster) in water. If you put a teaspoon of plaster in a gallon of water, exothermic heat generation should not be a concern. The exothermic reaction still occurs (converting anhydrite/bassanite back into gypsum), but the heat is greatly dissipated over a large volume of water.

The Ben Franklin account is well known. There is a brand of agricultural gypsum + anhydrite blend that is named after him for this reason. It is probably lost to history as to whether Ben Franklin was applying gypsum or calcined gypsum (plaster). Like any fertilizer, you are not applying heaps of the stuff when you apply it. A small amount, spread quite thinly, will not cause a significant heat buildup.

I have not heard of food grade gypsum before. If that works for you, go for it; ditto egg shells. The agricultural grade products are cheap and work fine for plants.

[tucker85]

I bought a small bag of soluble Gypsum made by Alpha Chemicals and sold on Amazon. It's intended for use as a fertilizer. Apparently Gypsum has been used as a fertilizer for hundreds of years. I would think that minerals meant for human consumption would be much more expensive.

[No-Pro-mwa]

I have been using it mixed with Epsom salts but not long enough to know if it is doing any good. I was crushing the pellets into a powder and then mixing it up. I'm not sure if that is how I am suppose to or not.

I also put about 3 5o lb bags in my garden every year and also sprinkle it on my lawn. I think it is really helping with that.

[kg5]

I have only been warned about using sulphur in the hot house covering I want to use as it breaks down the UV resistance to the plastic based covering. For what it is worth.

It is the best soil conditioner especially when the ph is getting very close to spot on. Use to buy it loose by the truck full.