Yellowing/Mottling - Culture issue?

[kmccormic]

Hi There!
I'm new to semi-hydro. This is a Phragmipedium Sorcerer's Apprentice in lecca, only plant in s/h. I received it in September. It had been in semi-hydro in lecca, and it seemed to be adapting pretty well to my culture. I put it outside in April in 30%-50% shade. I think there are 2 issues, one is the mottling, another is yellowing/browning at the ends of the leaves that just seems to come back.

Normally I do a rotation of weekly watering with tap water. 2 weeks 1/tsp KLite per gal, 1 week tblsp/gal Klepmax, 1 week plain tap water which is usually 150 tds and 9.5-12 ph and naturally high in calcium and minerals. I then use tiny amounts of citric acid to drop it to 6.5 ph. The s/h gets flushed 3 times, filled to the brim of the beads, before feeding. I was on furlough and starting to research, learning that there's a big difference between regular tap water and chelated calcium in sources like CaliMagic. And that potassium is a good thing to add once in a while.

I noticed that a lot of times my other plants had some yellowing/mottling in their leaves and wondered if they were dropping their bottom leaves faster than normal. I was starting to see some of the same yellowing at the ends and mottling in this plant and browning growing back at the end of previously trimmed leaves in May. I tried adding some epsom salts to water at a little less than 1 tblspn/gal. Then in June I also added CaliMagic for chelated calcium and magnesium. I was trying to keep an eye on the tds to keep it under 250 ppm, when I realized it was a bad meter and needed to be trashed. This week I have a new meter which seems much more accurate. Thinking I may have too much mineral buildup in the lecca, twice this week I used a 2 hour soak and refill with distilled water. There is some brown/green algae happening in the lecca within the water wicking line.

Pictures as I was trimming leaves:

[kmccormic]

I'm not sure if I should be unpotting it, trimming out the roots that have died since I originally potted it, or what else is going on. When this was happening on the 2 back growths, I wasn't so concerned, but in the last couple weeks it's happening on the leaves of the 2 younger growths, which are still putting out new leaves. And there is a tiny little new growth on the edge that, like all of us, I'd dearly love to see flourish!

Here's a picture of the pot, this is while filled with water as I flush, and using a flashlight to try to make it brighter. The second pic shows that the new roots, which had gone pretty brown, are now looking a bit greenish from the algae. And for some reason the pictures flipped 90 degrees when I posted them.


Cheers,
Kara

[SouthPark]

Originally Posted by kmccormic

I'm not sure if I should be unpotting it, trimming out the roots that have died since I originally potted it

kara ----- are those long dead roots the original ones? That is - when you first planted into leca ------ those were the original roots, right? If so, then that would probably be the expected case of old roots dying off, and new young roots coming out, which become adapted to the watery environment.

As for the leaf tip browning ------ if not enough water gets into the plant due to dying/dead roots, or fertiliser salt is drawing water out of the plant, then the tips can go brown or yellow in that way.

The nice thing is that you're getting new root growth.

And as for the rotting roots and thoughts about trimming the rotted portions ----- that is a good idea.

[estación seca]

Phrags grow in or beside streams of pure water, with very low nutrient availability. I think you're giving yours far too many minerals in the water.

In your hot climate you should be watering and flushing in S/H nearly daily. The mineral buildup on the LECA means it's happening on the roots as well. That would explain everything you're seeing.

You're probably using far too much fertilizer, magnesium and cal/mag. Algae in the pot confirms nitrogen excess. The yellowing/browning strongly suggests osmotic overload.

Kelpmax is a rooting promoter that doesn't need to be used very often at all, certainly not every 2 weeks.

Phrags were mentioned in passing in a lecture given by Brandon Lam, orchid curator at the Huntington. He said they get almost the same care as the Huntington Paphs. This involves very low levels of fertilizing. The Phrags but not the Paphs are misted overhead several times each day:
Paphiopedilums by Brandon Tam, Huntington - DVOS 2017 09 21

[camille1585]

I had similar thought - those leaf tips look like a reaction to excessive nutrients. With 1tsp/gal of Klite, you're feeding 160ppm N. You can easily cut that down to a third of that (50ppm N) with weekly applications, and with phrags I'd guess (but am no phrag expert) that you can go even lower than that.

If I understand you correctly, the plant does not get flushed between those weekly flushes prior to fertilizer application. With a once per week flush water is evaporating, further concentrating the nutrients, and compounding the problem.

It would be good to continue flushing the pot with some pure water (rain, distilled, RO) and then adjust your feeding and watering regime. Reduce the amount of klite, use kelpmax less frequently (once a month is sufficient), and I think you can stop the Calimagic entirely. You mention that your water is already high in calcium and magnesium, and K-lite is also providing them. I think the Calimagic would be interesting only if you had no other sources of Ca and Mg.

As a side note, I looked up CaliMagic out of curiosity. It contains Calcium carbonate, Magnesium nitrate and a bit of iron in chelated form (iron DPTA). The only chelated mineral is the iron, and the calcium source is one of the standard forms of calcium used for plant nutrition, and is it present in tapwater.

[kmccormic]

Thank you SouthPark, estación seca, camille1585!

I wasn't thinking originally that I was over-feeding, I thought it was a nutrient deficiency from the mottling/blotchiness. I wasn't seeing any white buildup on the lecca. With active growth season I thought they'd surely need what I usually give the others.

What I'd been doing was same as the rest of my collection. Once-a-week feed: Klite twice a month, and kelpmax once a month to help root growth in active growing season, with a week of water to flush any salt buildup and then I tried adding in some CalciMagic. The rest of the collection usually soaks for 20-30 minutes before I take them back outside. For s/h I flushed the lecca beads (fill so the beads on top are starting to float) 2-3 times each session before I would fill just to the driven holes with whatever the "feed" was that week. Then I'd "top off" a couple times a week with tap water up to the holes again, as I was giving the rest of the collection a quick mini-watering every few days. The concentration would have already have been increased within the beads though and I never thought about that!


The additives I was doing was based on Rick L Orchids who was saying that chelated calcium is better than tap water calcium because tap water isn't as available for uptake as chelated calcium - the iron in the mix is chelating the calcium for easier uptake. And I thought I'd need some kind of magnesium supplement, that the blotchiness/mottling was due to magnesium deficiency. A couple of Rick's videos, about 8-10 min. each:

[WaterWitchin]

Some phrags and paphs have tessellated leaves. If that's the mottling you're speaking of, it's normal.

And I'm on board with too many nutrients. If you're using KLite, no need for more supplemental CalMag, especially if you're using tap water. Same with the epsom salts. Ditto to what ES says about KelpMax. Once a month max, for routine care.

I don't know how others grow them, but here in Kansas I have to move paphs and phrags inside during most of July. They're mostly intermediate temp orchids, and I've noticed leaf tip damage with extended heat waves (95F-100+F).

[Ray]

Kara,

Don’t believe everything you read or see in videos. Rick L is incorrect about the “chelated calcium”. Chelation is done to make things water soluble. The calcium in your water supply IS in solution already! If the mineral is in solution, the plant is able to take it up.

Don’t trust TDS meters for actual readings. If you add 1 teaspoon of K-Lite to a gallon of water, the true TDS contributed by the fertilizer is about 1225-1250 ppm, and that must be added to the true TDS of the water. Read this.

Once you have stopped poisoning your plants with fertilizer and calcium supplements, I think you’re still going to have a problem because of the hardness of your water. If you’ve got a pH as high as 9.5-12, you’ve likely got VERY hard water. Adjusting the pH doesn’t change that. Phrags (and most orchids) don’t do well with very hard water. You may want to consider a small RO unit.

But first, if you are on a municipal water supply, look up the online water quality report. It will be focused on human safety, not plants, but you still might get some useful info. I also highly recommend you send a sample off for testing (I use the JR Peters Lab), as then you’ll know exactly what you’re dealing with.

[estación seca]

Orchids can't all be treated the same. Some tolerate higher solute loads; others don't.

[SouthPark]

kara ----- also, I have some Angraecum orchids sitting in their same pot for a few decades - each night watered by lawn pop-up sprinkler - with municipal water. They've never been manually fertilised. No mag-cal applications too. And they remain strong. So definitely not all info from videos should be taken as law.

On the other hand, it does make sense to check reports of local water supply tests - just to get an idea of what's in the town/city water, in order to assess suitability for the orchids.

I know that the water in my particular city is no problem for my orchids. But this might not be the case somewhere else in the world.