Calcium question
 

Hello everyone! I need some help please! Some of my catts were doing and not doing so well - they were growing like crazy but then the new growths kept on having issues I did not know what to do with. After some reading I came across an excellent article on calcium deficiencies and recognized my plants in the example pictures basically. So I clearly need to add calcium to my water (I should have thought of that since it has basically no calcium - as in, the last water report I saw had “values to low to measure” for calcium in a few of the months).

So after the boring background - the question. I could not find any calcium feed on my little island except one for tomatoes that says calcium nitrate 15.5-0-0. But I have no idea how to use it on my orchids since the instructions are for tomatoes - of which I have none :) those instructions are one cup to 50 ft of row - I don’t even understand what that means though I understand all the words :) thank you!

Treat it like any fertilizer. It's a 15.5-0-0-19Ca formula, so if you want 100 ppm N for weekly feeding, then you divide 9.2 by the %N = 0.594 ml/L (or 8/15.5=0.516 tsp/gal - I'd just use 1/2). The solution will contain 18/15.5 = 126 ppm Ca.

Personally, I'd mix it with my regular fertilizer to provide a more-or-less "continuous" supply of Ca.

Let's say I mix it 50/50 with a 10-12-8 formula, the 50/50 blend would be 12.75-6-4-9.5Ca.

If you want to feed that weekly @ 100 ppm N, then 9.2/12.75=0.72 ml/L or 8/12.75=0.63 tsp/gal..

Let us know later whether the situation with the growths improves after using the calcium for a while.

Thank you so much for the advice! First application done! :) I’ll report back after a while with updates. I was so upset with the new growths getting damaged when there were so many of them and growing so nice. Even more upset when in the end it was all my fault. Live and learn! I really should have known better because I read another post about water quality right here on the Board and went to check mine. But I did not put 2 and 2 together - low concentration of any sort of minerals with mineral deficiency. I’m usually smarter than this :) I hope things will get better for them, they were basically textbook pictures of calcium deficiency. I was afraid initially it was some black rot or something like that - except it did not spread to older growths at all. Anyway, one of the catts is growing a bud and I’m over the moon with it. It should bloom about the same time as all the phals I have which are all growing spikes. They probably suffered too, poor things, just more resilient than the catts so I saw no signs on them.

Maru ----- you can also use this approximation here:

Let's go with making a 100 ppm Nitrogen batch from your particular fertiliser with the raw 15.5% nitrogen written on the packet.

N = 15.5% written on packet
T = 0.01% (which is 100 ppm converted to % for the target concentration of the nitrogen)
X = ml of water you are going to use for your mix

Use the calculation below to get an approximate value for the amount of fertiliser you need to add to 'X' ml of your water in order to make the 0.01% nitrogen mixture.

F = {(T/100) * X} / [N/100]

Or just : F = {T * X} / N

The 'F' will just be grams of fertiliser required.

Let's just say we want to use 500 ml of water, or half a litre. X would just be 500. We know N is 15.5, and we want T (target concentration for the nitrogen) to be 0.01 percent, so T = 0.01

Doing the calculation will give F = 0.322 gram of fertiliser (if we wanted to use X = 500 millilitre of water).

That is - if we choose to use 500 ml of water, we need to put 0.322 gram (or approximately that much) of that particular fertiliser into the water. That would achieve the 0.01% (aka 100 ppm) nitrogen batch mixture.

that fertilizer has too much Nitrogen.
That would be as bad as feeding a lawn fertilizer of 30-10-10.

Orchids cannot handle that much N. It will lock out other Nutrients - you will do more harm than good using that stuff.

One application will be fine but do not use any more of it.

You should have a hydroponics store somewhere on your island. They will sell Calcium supplements.

Otherwise Epsom salt from a pharmacy contains calcium in a safer form for orchids.

Gardeners use Garden Lime. You might be able to get hold of lime but I have never used the stuff, you would need to work out how much to use. It raises the ph lots too so needs to be ablanced with ph down.

one thing you can definetely get hold of is eggs.
Egg shells contain a lot of calcium too so what some people do is crush egg shells into a fine powder and sprinkle that on the substrate.

Epsom salts is magnesium sulfate, there is not no calcium at all in it. Eggshells would be a good long term solution, but as it takes time to degrade and release the calcium (especially in airy, bark based substrate), she would need to start with a form that is quickly available to the plant in order to address the deficiency asap.

If hedoes as Ray suggests and mixs this high N fertilizer with what he uses normally and adjusts the dosage accordingly, it shouldn't be too much of a problem. As a note, too much nitrogen doesn't lock out other nutrients, but rather transitions the plant into extreme vegetative growth, producing lucious green growth, and there is no/much less energy going into reproductive growth.

looks like you are right camille, I now use Rainmix which has all the calcium in it already so don't need to worry about supplementing anymore - I had just read about it recently and turns out it is a perpetuated myth that I picked up and helped spread without realizing, makes sense that it doesn't contain any

The Epsom Salt Myth — Yard & Garden Report.

Everyone can do what they like at the end of the day, I might not be right about everything or the effects of too much N but I am right that it is no good. Your effects are less than desirable so now that we have pointed that out everyone can decide what they want to do.

I forgot to mention ..... that the equation in the above calculation is generally a good approximation.

If ever needed ----- the full equation will be:

F = {T * X} / {N - T}.

Normally ---- T will be quite tiny when compared with N ..... so the 'N - T' is roughly equal to 'N'.

The number of nitrogen on the label doesn't matter. It refers to what percent of the material inside is made up of nitrogen. Anything can be diluted to a reasonable nitrogen concentration. There is a fertilizer concentration calculator available on the First Ray's Web site. The other components in most fertilizers are present in adequate quantities when diluted to an appropriate nitrogen concentration.

As Ray mentioned above, calcium nitrite diluted to a nitrogen concentration of 50-125 parts per million (depending on how often the grower fertilizes) will likely have enough calcium for orchids.

I attended a lecture on slipper orchids given by Brandon Tam, curator of the orchids at the Huntington Gardens. For slipper orchids he uses well water plus calcium nitrite diluted to 10 parts per million nitrogen concentration, at every watering. Slippers are considered to need less nitrogen than other kinds of orchids, but even this low dilution gave them enough nitrogen.

Caribbean islands generally have coral sand at the beach. This is usually decomposed coral, which is high in calcium. You could make your own calcium supplement by rinsing coral sand and steeping it with water to which some acid is added. Vinegar would work. You would need to be able to measure the calcium concentration in the product, but once you arrived at the correct proportion of sand, water and acid, and the proper steeping time, you could prepare the supplement the same way each time in the future. Then you could use Ray's fertilizer calculator to calculate how much of your supplement to add to your fertilizer solution. I sense a business opportunity for you to market calcium supplements to other gardeners on your island.