Calcium and Magnesium source a concern?

[bethmarie]

Does the source of calcium (or magnesium) matter?

I just picked up a supplement that is Calcium Carbonate and Magnesium Nitrate. The solution is brown rather than fairly clear like my last CaMg supplement.

It's a mess to work with.

[snowflake3111]

Originally Posted by bethmarie

Does the source of calcium (or magnesium) matter?

I just picked up a supplement that is Calcium Carbonate and Magnesium Nitrate. The solution is brown rather than fairly clear like my last CaMg supplement.

It's a mess to work with.

I have not found orchids care much about Calcium or Magnesium your all around orchid fert should have it so no need to add more IMO. Orchids do not need as much ferts as most house plants. Orchids do like Nitrates aka Nitrogen. So that would not hurt. Some orchids do need more Calcium than others. It really depends on the type of orchids you grow I think.

I grow another type of plant that is a Magnesium HOG. I feel like this plant can not get enough of the stuff. Orchids are nothing like this plant.

[katrina]

Sounds like the color of the last one I picked up...kind of surprised me really. I looked at the label further and it turned out I had grabbed the one with iron in it. I've been using it and haven't had a problem.

[Leafmite]

Iron is a good thing for plants so if that is the combo you bought, your plants should be quite happy. I use Ironite with all my plants to give them a boost.

Which plant likes the magnesium? I know my Camellia seems to really like it. My Cinnamon tree really loves iron....

[bethmarie]

Thanks, Katrina, Leafmite!

[Orchid Whisperer]

I use gypsum for the Ca and Epsom salts for the Mg. A teaspoon of each per gallon of water. The solution also provides sulfur. The solution is clear and is easy to work with. I just add several ounces (maybe 1 cup) of the solution to what I use for watering plants.

Oh - and it is inexpensive too.

Gypsum you can get as pelleted gypsum in the lawn care section of home improvement centers. Or, Plaster of Paris serves the same purpose (essentially the same as gypsum). Epsom salts you can get at any pharmacy.

[estación seca]

Originally Posted by Leafmite

Iron is a good thing for plants so if that is the combo you bought, your plants should be quite happy. I use Ironite with all my plants to give them a boost.

Which plant likes the magnesium? I know my Camellia seems to really like it. My Cinnamon tree really loves iron....

A single magnesium atom is the business part of each chlorophyll molecule. Without magnesium plants cannot make chlorophyll, and turn yellow (chlorotic.) Many plants accustomed to neutral to acid soils can't extract enough magnesium and/or iron from alkaline soils, and turn chlorotic. Then you have the choice of 1) Epsom salts to the soil and foliar spraying of chelated iron; or, 2) acidifying the soil plus Epsom salts plus iron fertilizer.

Most plants from high-rainfall regions lie in this neutral-to-acid category. Minerals are washed down into the soil, and decaying organic matter near the surface provides organic acids that lower the pH at the root zone. Wetlands tend to have very low pH (very acidic) due to all the soil microflora generating lots of acidic organic matter breakdown products. This is why most bog plants, and many firs, are considered acid-loving plants.

A great example is Cestrum nocturnum in my garden. It's native to volcanic Caribbean soils with lots of rain. Here in our mineral-laden soils, with pH 8.0-8.5 tap water, it is very chlorotic unless I acidify the soil around it, or use a foliar iron spray.

Alkaline soils tend to be found only in areas with little rainfall. Here the little rain that falls tends to evaporate from the surface rather than move lower in the ground. As it evaporates it brings minerals (mostly sodium, calcium and magnesium salts) up to the surface. Desert plants tend to favor alkaline soil for best health. This is why it's hard to keep desert plants alive in typical peat-based potting mixes unless repotted every 1-2 years: the breakdown of peat changes the soil chemistry to acid, and these plants are highly susceptible to acid-loving fungi like Phytophthora.

[Orchid Whisperer]

Originally Posted by snowflake3111

I have not found orchids care much about Calcium or Magnesium your all around orchid fert should have it so no need to add more IMO. Orchids do not need as much ferts as most house plants. Orchids do like Nitrates aka Nitrogen. So that would not hurt. Some orchids do need more Calcium than others. It really depends on the type of orchids you grow I think.

I grow another type of plant that is a Magnesium HOG. I feel like this plant can not get enough of the stuff. Orchids are nothing like this plant.

It depends on your water supply, the type of fertilizer, and the type of orchid. If your water supply provides Ca and Mg, or your fertilizer contains these elements, great! Many water supplies, and many fertilizers, in the United States do not supply enough, and supplemental Ca and Mg are needed. You can tell when a deficiency exists (chlorosis as previously stated, disease susceptibility, etc.)

[snowflake3111]

Originally Posted by Orchid Whisperer

It depends on your water supply, the type of fertilizer, and the type of orchid. If your water supply provides Ca and Mg, or your fertilizer contains these elements, great! Many water supplies, and many fertilizers, in the United States do not supply enough, and supplemental Ca and Mg are needed. You can tell when a deficiency exists (chlorosis as previously stated, disease susceptibility, etc.)

Oh I thought they were adding more. All my ferts have both Ca and Mg so I was thinking they had a fert like mine and were adding more my bad.

[Leafmite]

Some orchids grow on limestone cliffs and that seems to influence a need for more calcium than some other orchids.