Calcium and magnesium supplements?

[Papillon24601]

How do you supplement your calcium and magnesium? I know a lot of people use Epsom salts. I'm having a little trouble, because if you fertilize weekly weakly, but you can't combine supplements, then do you alternate? And do you mix them with your regular fertilizer? And as we are slowing down for winter, while balancing the flushing.... Maybe I'm getting too complicated with all of it?

[Leafmite]

In the summer, I use powdered milk and Epsom salts (once a month) added to my water. In the winter, I use Cali-Magic. I also add eggshells and, during heavy growth, Ironite.

I use Cali Magic or powdered milk nearly every time I water. Plants need a constant supply of Calcium.

I don't really worry too much about alternating the nutrients any more. The plants have seemed fine.

[Papillon24601]

Thanks! How much powdered milk?

[estación seca]

Look up your water utility water quality report online. You probably have some calcium and magnesium (Ca and Mg) in your tap water. These two constitute much of what is referred to as "total hardness" or "total dissolved solids" (TDS.) You can use tap water for watering, or mix it with reverse osmosis to dilute if the tap water TDS are above about 500. Then you won't have to worry about supplementing with Ca and Mg.

Another approach is to use your existing fertilizer on your outdoor plants in the ground, and buy some orchid fertilizer container Ca and Mg. Michigan State University (MSU) blends contain Ca and Mg. The formulation I have shows 13 - 3 - 15 - 8 Ca - 2 Mg. It is not very expensive.

Milk powder in the soil will attract other nasty things, like roaches, flies, fungus and pathogenic bacteria. It may also smell bad.

[Papillon24601]

I read the report, but I don't know if that is enough. Bart Motes said if your orchid has a calcium deficiency, it will show red when stressed. My phals recently had a major stress, and about half turned red. So I think they need some calcium

[Leafmite]

I had issues long ago with Calcium deficiency and lost a few plants. At the time, I thought Orchid Fertilizer contained everything orchids needed (I have no idea why they do not).

If you are growing indoors, don't use the powdered milk as it will smell like sour milk if any doesn't dry quickly. That is why I only use it when the orchids are outside. I have not noticed it attracting any additional insects.
I use about a teaspoon per gallon.

The Calimagic is nice as it doesn't smell and it provides the calcium my plants need while they are indoors.

I also use eggshells but they cannot be the main source of Calcium as they decompose rather slowly. I recently bought little bonsai fertilizer baskets (for slow release fertilizer) and I have been putting crushed oyster shell in them. Both of these provide a nice, slow release of Calcium.

[gngrhill]

I also notice that garden gypsum is calcium. Found in local garden store.

[estación seca]

Originally Posted by Papillon24601

I read the report, but I don't know if that is enough. Bart Motes said if your orchid has a calcium deficiency, it will show red when stressed. My phals recently had a major stress, and about half turned red. So I think they need some calcium

He was talking about Vandas specifically. Also, I think he might have been talking about magnesium and not calcium. Phals turn red when they get lots of light. It's not bad for Phals to be red.

[Ray]

Originally Posted by gngrhill

I also notice that garden gypsum is calcium. Found in local garden store.

But gypsum isn't very water soluble. That's fine, sitting in soil where it can slowly dissociate, but in the transient exposure of orchid watering, it's not going to be as effective as other products.

[isurus79]

I add liquid Cal/Mag supplement every time I water my plants and I follow the instructions on the label.

Easy peezy. No need to get more complicated than that!