Epsom salt/MgSo4 for yellow phal leaves with unexpected "side effect"

[ALToronto]

Lime plaster is probably the most common. If you go to an agricultural supply store, you should be able to buy Calcium Nitrate, which will also provide Nitrogen.

[No-Pro-mwa]

I have been mixing epsom salts and gypsum together, I think 1 Table of each to a gal. see I'm not doing it enough, I have to find my recipe.

[Vanda lover]

I have read that you can grind up some of your calcium
pill supplements or use oyster shell.

[DavidCampen]

Originally Posted by shushu45

What would be a good source of Ca??

I use Botanicare brand "Cal-Mag Plus"; it is available from most any hydroponics store.

Cal-Mag Plus

[Orchid Whisperer]

Originally Posted by ALToronto

Lime plaster is probably the most common. If you go to an agricultural supply store, you should be able to buy Calcium Nitrate, which will also provide Nitrogen.

I sure hope you mean plaster of Paris and not lime plaster. Lime plaster can have quite a high pH, and also sometimes has fly ash from coal-burning power plants as a filler material. Plaster of Paris is basically just gypsum that has been heated to drive off water that is part of the mineral structure.

You could use plaster of Paris, or you could use other forms of gypsum. I use the pelleted gypsum that is sold for lawns, about 1 teaspoon per gallon of water, allow it to dissolve overnight, decant off the liquid, dump the remaining solids on the lawn. I add a teaspoon of Epsom salts to that decanted liquid, thus providing a cheap source of Ca, Mg, and S. I add some of this (several ounces at a time) to my fertilizer mix when the plants are actively growing, or sometimes add to the water even without the fertilizer.

Calcium nitrate is fine, but use it separately from the Epsom salts and gypsum (nothing will "go boom", but chemical reactions will cause sulfate minerals to precipitate).

[tucker85]

I disagree that you need to give calcium with magnesium. You can use epsom salt to supplement magnesium. I know lots of growers who use it. But calcium is also important so if you want to use both calcium and magnesium I suggest a cal/mag type fertilizer or use a cal/mag supplement available from hydroponic stores or on-line.

[shushu45]

Could one use Ca supplement pills, crush them up and put it in the water??

[HighSeas]

I think you should be able to do that but there are cheaper and more effective ways of accomplishing the deed.

[Ray]

Magnesium is mobile within the plant - if you don't provide it, the plant will relocate it from elsewhere, and when you do provide some, it will be well distributed.

Calcium, on the other hand, is not relocatable, so should be provided regularly, so it can be delivered to newly-growing tissue.

Before folks go crazy with supplements, and add them to the point of really screwing things up, please consider that the demand for nutrients is very low in orchids, and when it comes to calcium and magnesium, there might be a sufficient amount in your water supply, precluding the need for any supplementation.

[shushu45]

Originally Posted by Ray

Magnesium is mobile within the plant - if you don't provide it, the plant will relocate it from elsewhere, and when you do provide some, it will be well distributed.

Calcium, on the other hand, is not relocatable, so should be provided regularly, so it can be delivered to newly-growing tissue.

Before folks go crazy with supplements, and add them to the point of really screwing things up, please consider that the demand for nutrients is very low in orchids, and when it comes to calcium and magnesium, there might be a sufficient amount in your water supply, precluding the need for any supplementation.

Would this "screw things up" for them??

Add 1/2 Tbs of Mg to per gallon of water every other watering. And a 1/4 of tsp Ca to pre gallon of water every three weeks. Just for the growing season and when infected.