How do I calcium?

[astrid]

Hey guys!

I have noticed that some of my orchids are yellowing a bit. This is not due to light, and doesn't seem to be due to an infection or fungus.

I've also had a couple orchids that get black leaf tips and softened and falling-off new growths! Grr!

These symptoms led me to realize that at least a few of my plants are suffering from a deficiency in calcium. I think most of the fertilizers I use are just N-P-K, and don't seem to offer supplemental calcium.

I ordered some water soluble calcium from a hydroponics store on amazon (link), and I need to know the following:

1- How many ppm calcium should the plants have? (I'm majoring in chemistry so the math part doesn't scare me!)

2- How often should they have it? Should it be a one-off, or should it be added to my monthly fertilizing of the plants?

3- Should I give it to all of my plants for good measure, or should I only give it to plants that seem to be suffering? This is a preventative/proactive vs reactive medicine question.

4- Do you guys have a favorite Ca supplement that you give to your plants? I would love recommendations. I bought the product I bought because it was cheap and would come quickly.

5- Is my understanding of the symptoms of a Ca deficiency correct?

Thanks, everyone! I included a picture of my "worst" plant so you can help me discern its issue if the Ca deficiency isn't it! Thanks!

[MrHappyRotter]

What types of plants are we talking about? What kind of fertilizers are you applying, how often, and what rate(s)? What's your watering routine and what kind of water?

I'm asking these questions for a few reasons. First, calcium deficiency isn't generally a problem that develops quickly, it usually takes a long period of time before plants like orchids would show any sign. Second, in situations where symptoms do show up, it's far more common to be a result of plants being watered with or grown in a substrate that is on the extreme end of the pH range OR in cases where other nutrients like iron, magnesium or potassium are out of balance. The pH can affect availability of nutrients in general, and different plants may have different pH requirements. Certain nutrients "compete" with each other, and if things are out of balance, will prevent the plant from gaining access to the others.

In any case, it almost always safer to address the root cause of the issue, rather than add more of anything. Calcium and most nutrients aren't necessary in large amounts, and in the case of orchids, when it comes to nutrients and minerals, less is more.

If you are watering with very pure water, like RO or DI, the better option is to make sure you're adding in about 20% - 25% municipal water, which generally speaking is going to have more than enough calcium for your plants.

In cases where you absolutely know your plants are suffering from calcium deficiency or you're growing plants known to prefer/need extra calcium, then you may consider supplementing. If you're going that route, follow the directions on the additive, don't over do it. Personally, I prefer to use slow release options: oyster shell, limestone, egg shells, crushed coral, things of that nature. But in any case, use them sparingly. It's very easy to overdo it and swing the pH too high, or make other nutrients unavailable due to competition.

[Leafmite]

I use eggshell. It doesn't release Calcium right away but as it decays, there is a nice, slow, steady supply. If a new orchid has new growths that blacken, I might add a TUMS or Calcium tablet (as I did with my Cochleanthes discolor).
As MrHappyRotter has said, Calcium deficiency takes a while to appear. Iron and Magnesium deficiency seem to appear much more quickly. Your medium's pH and ability to absorb nutrients will have a great effect
I have used red lava rock for many years and when I used goldfish pond water (with fertilizer tablets for the lotus and lilies), I never had a problem with my plants/orchids. When I switched to using fertilizers specific to the plants and rain/distilled water, I started to have problems. Now I add the eggshells and, in late spring, a little Ironite goes into the watering can to slowly dissolve over the summer...then every week, I add a pinch of magnesium to the watering can and, sometimes when the temperatures are high, powdered milk (the plants are outside).
As you are growing in bark and moss, you should have an easier time with the fertilizers on the market for orchids as all of them seem to be made for moss and bark. Good luck!

[Stray59]

Leafmite -
What is the powdered milk for? I haven't heard of that before....

[astrid]

Originally Posted by MrHappyRotter

What types of plants are we talking about? What kind of fertilizers are you applying, how often, and what rate(s)? What's your watering routine and what kind of water?

The plant in question is pictured and the tag is clearly shown

I mostly have oncidiums, a few paphs, some dens, and some phals. I worry most about the pictured plant and my miltoniopsis orchids.

I am willy nilly with fertilizer. I alternate a miracle gro orchid food with a 7-7-7 all-purpose plant fertilizer once a month. I have applied superthrive to several plants lately with nice results, but I don't think that has calcium so it won't really help my plants on that front.

I just use the recommended fertilizer strength mixed up, and I apply it after I have watered my plants while their potting media is still damp.

I water my oncidiums twice per week, my phals once per week, my paphs when the moss is feeling dry, and my dens whenever their canes start to wrinkle slightly and their media is dry. I use regular tap water.

[MrHappyRotter]

Originally Posted by Stray59

Leafmite -
What is the powdered milk for? I haven't heard of that before....

Once it dries, it sticks to the mount or potting mix. It provides a little more calcium and trace minerals than tap water, and as the various bacteria and fungi break it down, provides macro nutrients like nitrogen. It's sort of a biotic fertilizer, and nutrients aside, it may help culture the good bacteria and fungus that facilitate nutrient uptake.

You wouldn't want to use it indoors, obviously, since decaying milk would lead to lots of foul odor. It's also something that could attract lots of critters (ants, flys, gnats, etc), so it's not for everyone.

[astrid]

Originally Posted by MrHappyRotter

First, calcium deficiency isn't generally a problem that develops quickly, it usually takes a long period of time before plants like orchids would show any sign. Second, in situations where symptoms do show up, it's far more common to be a result of plants being watered with or grown in a substrate that is on the extreme end of the pH range OR in cases where other nutrients like iron, magnesium or potassium are out of balance.

This plant is potted in the same potting media as the rest of my orchids (I add sphagnum in different amounts depending on the individual needs of the plant), so the pH shouldn't be weird. My plants all get roughly the same treatment.

This plant has just been slowly suffering as the year has gone by and the yellowing has arisen very subtly. I thought at first it was getting too much light, so I put it on my phalaenopsis shelf, but now I know that it must be something else because it continues to lighten as the weeks go by.

---------- Post added at 09:02 PM ---------- Previous post was at 08:58 PM ----------

Originally Posted by Leafmite

I use eggshell. It doesn't release Calcium right away but as it decays, there is a nice, slow, steady supply. If a new orchid has new growths that blacken, I might add a TUMS or Calcium tablet (as I did with my Cochleanthes discolor).

How would I use egg shells? I was thinking of doing it as I eat softboiled eggs quite often and wind up with a lot of shells.

Would I just mix up shells in the potting media all crunched up? As it decays, can it produce mold? I don't think it would because cleaned off egg shells I think are only made of minerals, but it doesn't hurt to ask!

As for TUMS, do you just crush it into a powder and mix with water?

[MrHappyRotter]

Originally Posted by astrid

The plant in question is pictured and the tag is clearly shown

I mostly have oncidiums, a few paphs, some dens, and some phals. I worry most about the pictured plant and my miltoniopsis orchids.

I am willy nilly with fertilizer. I alternate a miracle gro orchid food with a 7-7-7 all-purpose plant fertilizer once a month. I have applied superthrive to several plants lately with nice results, but I don't think that has calcium so it won't really help my plants on that front.

I just use the recommended fertilizer strength mixed up, and I apply it after I have watered my plants while their potting media is still damp.

I water my oncidiums twice per week, my phals once per week, my paphs when the moss is feeling dry, and my dens whenever their canes start to wrinkle slightly and their media is dry. I use regular tap water.

Based on your answers, I'd say calcium deficiency is extremely unlikely, so hopefully that's good news. It doesn't mean the calcium supplement you bought is a total waste, but I personally would not recommend using it more than a few times a year as a booster.

Tap water is going to have more than enough calcium for your orchids, and the miracle grow almost certainly has added calcium as well. Superthrive should be used sparingly except after repotting. It's good stuff, don't get me wrong, and I use it in combination with seaweed extract as a supplement.

Depending on the type of paphs you have, there are some that prefer a bit of added calcium in their diet. In fact, most will appreciate a little added calcium, but there are some major exceptions, such as Paph. delenatii. Even then, it's not so much an issue of calcium, it's just that delenatii prefers a more acidic environment, and as you know, calcium tends to raise pH.

One remedy you might want to consider is switching to reverse osmosis, distilled, or deinoized water for the worst affected plants. It could be the combination of tap water and fertilizer is just too much for some of your plants. If you go that route, you still want to mix in 20 - 25% tap water, you shouldn't use pure water on the plants. I don't know what the water quality is like in your area, and chances are it's fine for most orchids, but I'm also certain that your Miltoniopsis is fairly demanding when it comes to water quality, so RO/DI water is a good bet if you want to improve their overall health.

Another possible remedy, and I encourage you to do some research before going this route, is to try a low potassium/phosphate (low k) diet. There's some evidence that the levels of potassium in most common fertilizers is excessive (and toxic) to tropical epiphytes, and the suggested symptoms are things like susceptibility to rot and leaf tip die back, which sounds like what you're dealing with.

[Leafmite]

More calcium. I started growing plants as a child and many of the older gardeners that helped me along with my hobby swore by milk and eggshells (for their gardens and potted plants). Seems to work very well for me (as long as the plants are outside when I add the small amount of powdered milk). Very old-fashioned and a little wacky, certainly.
I do have the MSU fertilizer for rain/distilled water but I am guessing that the lava rock and LECA is one of the reasons it doesn't work as well as it should for me.
I don't know if you have read any of the other times I have posted about calcium deficiency but I had a pond for thirteen years and used that water for my plants spring-fall, very rarely ever using fertilizer. When I broke down the pond, I switched to rain/distilled water and began to use an orchid fertilizer for the orchids. That fall, I went through the nightmare I call the "Black Plague" and lost quite a few very nice orchids.

[MrHappyRotter]

Originally Posted by astrid

How would I use egg shells? I was thinking of doing it as I eat softboiled eggs quite often and wind up with a lot of shells.

I'm not sure if this is what everyone does, but here's what I do...

I wait until I can collect at least a dozen or more egg shells, keeping them in a plastic container in the refrigerator until I'm ready for processing.

Then I soak them in water for at least a few days, sometimes more. I fill a container with water, making sure the water covers the shells completely, then empty and refill daily to try and get off all of the membrane that sticks to the shells.

The soaking and membrane removal is mostly so that they don't produce odor and so they don't attract ants/roaches/gnats/etc, if that's not a concern for you (i.e. you grow outside) then it may not be an issue.

Once I've done the soaking, I put them in a plastic bag and crush them down to small pieces. Then I'll set that out on foil or plastic and let it dry completely until the pieces don't stick together.

Then, if I'm repotting, I'll mix a teaspoon or two into the potting mix, depending on pot size. Otherwise, I just sprinkle the shell fragments on top of the potting mix (top dress) plants. Repeat once or twice a year. It's actually one thing I don't worry too much about over doing, since it takes so long for the shells to break down.

Egg shells not only provide calcium, they provide several other trace nutrients, and they break down slowly, so they're good stuff.