# Disa aurata



## naoki (Aug 27, 2014)

This is from May 2014, but I'm still trying to catch up with my photo editing from this spring/summer.





Disa aurata, on Flickr

I got it from Wally Orchard of Afrodisa this spring. So I can't take a credit of flowering it. But it is still alive at least. His plants are very nice, and he is very helpful (and his price is too good). This is my first year with growing Disa, and I already killed 2x D. uniflora (maybe the night time temp wasn't cold enough, or I didn't give enough water). I need to get more D. uniflora...

I can see why Disa is so addicting, and I enjoyed reading Tenman's article here. I'd love to learn about the culture of stream Disa from other Disa growers!


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## Lmpgs (Aug 27, 2014)

Thankfully, not for our climate.


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## TyroneGenade (Aug 27, 2014)

The big issue is keeping them cool and damp in the summer. In your case, if you are not growing them under lights in the winter they may not be getting enough light. These plants are active growers all year round. There is only a brief period in May/June where the old growths senese and the young ones emerge. The other big no-no is moderate fertilizer---it seems to kill them. Fertilizers need to be very dilute but constant for good growth. This is why semi-hydroponics seems to work so well for them.


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## naoki (Aug 27, 2014)

Thank you, Tyrone. I'm growing them under lights, but I wonder if it will get enough light. Also, getting low temp in the winter is a challenge for me once the heater kicks in.

I was trying lower fertilizer for D.uniflora, but it might have been too much (it was around 15ppm N MSU in rain water once a week or so). For the surviving ones (D. aurata and D. tripetaloides), I'm trying to reduce it further. But I'm getting this pale leaves in the newer growth. Do you have any idea what's going on? Disa seems to be completely different from other orchids, so I'm not sure how to deal with it.


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## SlipperFan (Aug 27, 2014)

I am impressed with anyone who can keep Disas alive for more than a year!


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## TyroneGenade (Aug 27, 2014)

Can you tell us a bit more about your watering and fertilizer. Also, can you provide a close-up of the yellow leaves and a healthy looking green one. What lights are you using?

Table Mountain gets about 200 microEinsteins/m2/s on a winter day---but this will be mostly in the morning. Do you have a lux-meter and can you tell us the name of the lamp you use (we can work out the light in microEinsteins).

Bye


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## naoki (Aug 27, 2014)

Thank you for the info Tyrone. I thought that they naturally grow at a higher intensity light.

They are under T5HO (ebay plant spectrum with enhanced red+blue) + cheap warm white LED. I just went to measure it, and it is 100 micromole/m^2/s for 13 h/day. With considering the constant light vs natural light, the cumulative amount of light is similar to 150-200 micromole/m^2/s of peak natural light. Some rupicolous laelia (thin leaved kinds) seem to flower well at this relatively low intensity. But the measurement is with a really old Li-Cor quantum sensor, which I scored from ebay, and it needs routine calibration. I feel like that Disa may be happier with more light. For D. uniflora, I was keeping it under direct sun (but not so strong in AK, I guess).

I top-water them every 2 days (or every day) with rain water (10ppm TDS). The media (mostly perlite with some sphag) seems to be wet all the time. Fertilizer used to be 30ppm N (mostly MSU, but other stuff, too) twice or once a week. But after D. uniflora flowered and declined (with no new pups), I reduced to 15ppm N once a week or so (about a month ago).

Here, I blew up the picture of the leaves (around the region where there are yellow and green leaves). Can you tell anything from this?




I think the green part is probably from the growth under Wally's cultivation. If it were some nutrient deficiency, it would be relatively phloem-immobile elements (Ca, Fe, Mn, Cu, B, S etc.) since the older leaves are not so influenced.


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## naoki (Aug 27, 2014)

SlipperFan said:


> I am impressed with anyone who can keep Disas alive for more than a year!



I agree, I wonder how many more Disa I have to kill to get there!


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## NYEric (Aug 27, 2014)

Nice. Besides being hard to grow, they are also kind of hard to acquire here.


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## TyroneGenade (Aug 27, 2014)

Hello,

I think the light is adequate given the success with the Laelias. Also, the plant lamps are really heavy in the blue and red (where it really counts). 100 uE/m2/s of a plant lamp is possibly just as good as 250 uE/m2/s of a warm white lamp...

Now to state a giant, over blown, fertilizer debate...

The pale leaves with dark veins can be caused by three different nutrient deficiencies:
K
Mn
Zn

To speak of K-deficiency here is some what anathema as of late... But the descriptions matches what we are seeing: "Older leaves may look scorched around the edges and/or wilted. Interveinal chlorosis (yellowing between the leaf veins) develops." 

For Mn the symptoms are: "Growth slows. Younger leaves turn pale yellow, often starting between veins. May develop dark or dead spots. Leaves, shoots and fruit diminished in size. Failure to bloom." And for Zn: "Yellowing between veins of new growth. Terminal (end) leaves may form a rosette."

In these discussions I always like coming back to Mulder's Chart: 






Mn and K are related. If you have too little of one, you will see symptoms of the lack of the other. MSU is 13-3-15 so even if you are supplying 15 ppm N your plants should be getting enough K so I suspect the issue is Mn. While it is still sunny and warmish outside, I suggest you fertilize with something like Kelpack or Nitrosol or Seagro once or twice a week (you don't want to use Nitrosol & Seagro indoors, it stinks). These have been used to grow Disa's before, used as a foliar feed. (Seagro is what Jim Holmes of Cape Seed and Bulb uses. He mostly grows Disa uniflora hybrids.) These 3 are rich in Mn but relatively light on the K.

All the best with the Disa!

Eric, contact Wally. He had plants for sale. I was going to give it a try but decided to wait until next growing season.


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## Ozpaph (Aug 28, 2014)

lovely flower


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## Linus_Cello (Aug 28, 2014)

NYEric said:


> Nice. Besides being hard to grow, they are also kind of hard to acquire here.



Well, there's now a source in AK.


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## naoki (Aug 29, 2014)

Linus_Cello said:


> Well, there's now a source in AK.



I'd like to be able to do from seed to seed of Disa, but it's a long way to get there!

Hmm, so Tyrone, you think it is nutrient deficiency. It could be deficiency caused by excess. Interference is usually the issue when the overall concentration of fertilizer is too high for the species. Well, it could have caused the dehydration of root (burn), and they may be physically damaged. I could check the damage, but I was told that it is better not to disturb the root for this particular species. Everyone says that they don't need much nutrient, and over fertilization is one of the main causes of Disa death.

The difficult decision is whether the deficiency is caused by interference among elements (over fertilization) or lack of it (under fertilization). I could give mancozeb, but I think I should probably take the safer route of reducing fertilizer further more at first.


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## NYEric (Aug 29, 2014)

Linus_Cello said:


> Well, there's now a source in AK.



When I search, AfroDisa there is no price list, or catalog. Are you the source now!?


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## naoki (Aug 29, 2014)

Eric, his price is really good. I hope it's ok to post it, but the seedlings are $10-15 (but some of these will flower next year). BS is around $15-20. Flask was around $25, I believe, but you need to wait for the next spring. I'm only interested in species, but he does have lots of hybrids, too. Some stuff he listed last time are D. uniflora, D tripetaloides, D Kewensis, D Golden Age, D Yellow Bird, D Michael Gallagher x D uniflora.


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## NYEric (Aug 30, 2014)

Hopefully we can get a catalog/price list. Thanks.


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## TyroneGenade (Aug 30, 2014)

Email Wally and he will tell you what he has and what the prices are.

Naoki, you make a very good point. Some Disa growers have claimed the best growth by simply watering with distilled water. But the largest plants I have been told about were getting dilute Seagro on a weekly basis (or was it daily basis, I forget?). Over fertilization is a killer with these plants and that is how I have dispatched most of mine.

If we take the standard hypothesis here: too much K, then we could get interference of the uptake of Mg and N. A lack of bother would cause chlorosis but the symptom of the latter is small pale leaves, and as N is mobile you would see degeneration of the older leaves. Mg on the other hand presents as normal sized leaves that are pale and the older leaves become chlorotic between the veins, not like we see here with new leaves being chlorotic. Everything points to an immobile nutrient and our options are Mn or Zn.

This is a useful document to have around: http://www.mgofmc.org/docs/nutrientdeficiency.pdf 

High Fe can inhibit the uptake of Zn and Mn. Phosphate inhibits the uptake of Zn and Cu that of Mn. Could there be a P or Cu excess? But now we have abandonded Occam Razor and have an explanation more complicated from the simplest one:

Mn deficiency symptoms: "Yellow to white colored leaves, but with green veins. First noted on new growth. May have a typical 
"gray speck" symptom. "

Disa tolerate dilute foliar feeds well and the organic based formulas (Kelpak, Seagro/Seagrow etc...) provide ample Mn and relatively little K, P etc... Kelpak contains 8.40g Mn per L compared to 3.6:8.2:7.2 NPK. Mn is needed in only trace amounts so a little foliar feeding with the Kelpak should quickly clear up an Mn shortage while not offering too much NPK. I have used Kelpak on Disa at 1/2 the recommended dosage.


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## naoki (Aug 30, 2014)

Thanks Tyrone. The document is a nice summary.

I do use kelp product, but I consider it to be more of hormonal than nutritional value (well, it is an expensive way to supplement nutrients). I think you meant 8.4mg per L of Mn in Kelpak (from Ray's number), which I wouldn't call high Mn. Also percent NPK is 0.36:0.82:0.72, right? 1000 ppm = 0.1%

If you use 2 tsp/gallon, Mn concentration of KelpMax is 0.0219 ppm.
With 10ppm N of MSU, Mn concentration is 0.0682 ppm (3 times more than KelpMax). So you are right, that it can increase Mn without increasing the macro-elements. But it does increase the EC (and interfere with root osmotic pressure). When I measured 2TBS/gallon of MaxiCrop (they are more diluted than KelpMax), it gives 335 microS/cm (approx. 190ppm TDS).

Anyway, if it doesn't improve in a couple months, I'll probably try Mancozeb.


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## tenman (Aug 31, 2014)

Linus_Cello said:


> Well, there's now a source in AK.



Who is the source in AK?


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## tenman (Aug 31, 2014)

Beautiful flowers!


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## cnycharles (Aug 31, 2014)

Very nice


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## TyroneGenade (Aug 31, 2014)

naoki said:


> I think you meant 8.4mg per L of Mn in Kelpak (from Ray's number)



The document I was looking at, http://www.omex.com/agriculture/ProductItem.aspx?id=338, gave the value in g. I guess it was a typo... Oops.

If you are feeding MSU, and MSU has more Mn then the issue could be interference due to another nutrient. So, what are the Ca, Fe and Cu levels in MSU? Maybe you should flush the plant and get rid of as much residual nutrients as possible. What is the potting medium?


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## Rick (Aug 31, 2014)

naoki said:


> I Everyone says that they don't need much nutrient, and over fertilization is one of the main causes of Disa death.
> 
> The difficult decision is whether the deficiency is caused by interference among elements (over fertilization) or lack of it (under fertilization). I could give mancozeb, but I think I should probably take the safer route of reducing fertilizer further more at first.



I think you be hard pressed to find even 1 or 2 ppm of total N in waters that D aurata grows.

If they really need that much N it would be direct transfer from nitrogen fixing bacteria on the roots since the limited data on water quality in South Africa generally agrees with the rest of the world that if more than a ppm or 2 of N is showing up in surface waters then it's pollution from anthropogenic sources.

I think its really hard to kill a plant from mineral nutrient starvation. Since the whole low K thing, I've been cutting back more and more in the GH and the tropical plants growing on my windowsill are getting nothing but my well water (Which is "non-detect" for NPK). I've got a rescue hybrid Phal on the kitchen counter that hasn't been fed for a year, and grew a new set of nice dark leaves just fine.

I think cutting back is the way to go too.


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## naoki (Sep 1, 2014)

Thank you, all. It is in mostly perlite (the normal/small size) with a bit of chopped sphag. I have soaked them in pure water overnight a couple days ago. I should have measured the pour-through, but I forgot.

After rereading tenman's article, he rarely fertilizes them. Actually, there are some yellowish leaved plants in tenman's homepage. Do you know the cause, or is it not an issue?


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## naoki (Sep 8, 2014)

After couple advises here, I looked around additional scientific studies of Disa culture (hybrid with D. uniflora as the parent), and I found a pretty nice thesis here (scroll down to see the link to PDF):

https://scholar.sun.ac.za/handle/10019.1/3042?show=full

I thought that it might be helpful to some of you.

One of the chapter is published in a peer-reviewed journal (South African Jounral of Plant and Soil 2007 24(3): 166-171), which is about the nutrients.

The experiment showed large effects of NH4:NO3 ratio (which we have discussed in ST many times).


```
NH4:NO3   root.growth leaf.area
  0:100   230 (ab)    13.9 (b)
  20:80   176 (b)     14.2 (b)
  40:60   514 (a)     20.9 (a)
  60:40   422 (ab)    22.2 (a)
```

root growth is measured in % growth over 266 days.
leaf.area is cm^2
The letters in parentheses indicate the statistical differences. For example if you look at the leaf area, 0% and 20% NH4 treatments had significantly lower leaf area than 40% and 60% treatment.

I wonder if high preference of NH4 may be related to the habitat, some phrags may prefer NH4 over NO3, too? But I guess since temperature dependence of ammonium toxicity (high temp -> more problems with NH4) is found in some plants, high preference of NH4 by cool growing Disa might be an exception.

Condition: 18C day, 13C night, gravel based media, ebb-and-flood hydroponic once a day in winter and twice a day in summer, EC of 0.24mS/cm for the first 2 months and 0.41mS/cm for the rest, pH 5-6.5, 56-69% shade.

So I guess MSU and K-Lite with 100% NO3 may not be so great for Disa.

There are a couple interesting things in the other chapters which I haven't read yet.
- Ammonium nitrate was better than Urea for foliar feeding.
- Drip irrigation was better than Ebb-and-flood.
- Cooled root reduced root growth
- Hydroton (LECA) wasn't suitable for Disa.


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## Rick (Sep 8, 2014)

Can you find clarification that the EC was all due to fertilizer in RO/DI/or rain water?

The EC of the basic irrigation water can potentially account for just about all the salts and still have no NPK whatsoever.

What was total N concentration in the drip feed? And the dilution rate?

I've seen habitat info with high ammonia % but total N still under 5ppm. pH will become critical at higher ammonia concentrations as it becomes exponentially more toxic with higher pH (and temp).

I would agree in general that tiny frequent applications are better than big infrequent applications. Plants are trying to grow 24/7 and not just on feeding day. Most of what we dump on the plant on feeding day is wasted, and unavailable the rest of the time.


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## TyroneGenade (Sep 8, 2014)

Darn. LECA was my plan for next year. I will have to download the thesis and give it a careful look.

I don't think there is any problem with the you N-source. Your plants are growing well. The issue with uniflora hybrids is that they can flower so well that they don't bother setting a new tuberoid. You have to cut the stem or remind the plant that winter is coming by keeping it really cool.


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## TyroneGenade (Sep 8, 2014)

About the LECA:

From the thesis: "Hydroton with a layer of palm peat on top and hydroton with a layer of acid peat on top. The pH of the acid peat was altered by the addition of agricultural lime (5.6 g/L). "

I'm not sure how anything grows in that... Still, bad news for my Disa experiment for next year. Then again, they weren't using K-lite.


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## naoki (Sep 9, 2014)

Rick said:


> Can you find clarification that the EC was all due to fertilizer in RO/DI/or rain water?
> 
> The EC of the basic irrigation water can potentially account for just about all the salts and still have no NPK whatsoever.



Rick, they mixed the fertilizer from basic salts, so it is most likely that the EC is from fertilizer (i.e., they don't mention specifically, but I can't imagine that they would use tap water or well water for scientific experiments about nutrition). I found out the published paper is also freely accessible, so I added the link above. It's in their Table 1.



Rick said:


> What was total N concentration in the drip feed? And the dilution rate?
> 
> I've seen habitat info with high ammonia % but total N still under 5ppm. pH will become critical at higher ammonia concentrations as it becomes exponentially more toxic with higher pH (and temp).



I haven't read the drip feeding chapter yet. I think you can calculate the N concentration for the ebb-and-flood (from Table 1 of the published paper), but it seems a bit tedious, so I haven't done it. Also, there seems to be an error/typo about EC: the table says 0.73mS/cm, and the text says 0.24-0.41mS/cm.

The thesis did mention that they have tried even higher fertilization (about twice). Contrary to what we expect for Disa, they could handle it for the short-term. However, as expected, shoot:root ratio become high; i.e., more above ground biomass as we expect from higher fertilization (this pattern is common in plants). Higher fertilization also resulted in lower probability to develop tuber, so the plants end up dying after flowering. I've heard this kind of death after flowering is pretty common in D. uniflora, so reduced fertilization is required. Well, low fertilization is what everyone says, but it is good to see the numbers in a controlled experiment.

You are right about pH and temp. They were looking for the interaction between temp and NH4 toxicity, but they didn't see it. I think in the potting media chapter, I think the low pH of the media was important. I'll probably start to adjust the pH with vinegar (like for Cyp. acaule).

Tyrone, I received 7 more seedlings of D. uniflora today, and I was also planning to use LECA for some. But after seeing the high death rate in the experiment, I didn't use it. They don't explain why LECA is so bad for Disa, but it could be just their setting. But they quoted that Wally Orchard's article also mentioned that LECA isn't great for Disa.


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## Rick (Sep 9, 2014)

naoki said:


> Tyrone, I received 7 more seedlings of D. uniflora today, and I was also planning to use LECA for some. But after seeing the high death rate in the experiment, I didn't use it. They don't explain why LECA is so bad for Disa, but it could be just their setting. But they quoted that Wally Orchard's article also mentioned that LECA isn't great for Disa.



I've found that the LECA I have (I think purchased as Hydroton) has a high CEC capacity and holds up salts pretty easy. Could be a big K sink and ultimately run the root dose of K very high.


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## naoki (Sep 9, 2014)

Rick said:


> I've found that the LECA I have (I think purchased as Hydroton) has a high CEC capacity and holds up salts pretty easy. Could be a big K sink and ultimately run the root dose of K very high.



That's a possibility (they used even higher EC fertilizer for testing the different media). But doesn't Sphagnum moss have even higher CEC?


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## NYEric (Sep 9, 2014)

Chem nerds!


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## TyroneGenade (Sep 9, 2014)

Rick said:


> I've found that the LECA I have (I think purchased as Hydroton) has a high CEC capacity and holds up salts pretty easy. Could be a big K sink and ultimately run the root dose of K very high.



I think the idea with the peat was to push the positive salts (e.g. K) off the medium (i.e. LECA) with hydrogen ions... But all they managed was to smother the roots as, no doubt, the peat got between the clay and created a nasty bog.

The solution may be to water with a mildly acidic fertilizer? Perhaps some tea in the RO water to routinely rinse the LECA? I have noticed salt buildup on the top layer of LECA around my Paphs. I just blast this off with the spray bottle or switch out for clean LECA. Salt accumulation could become a problem without regular flushing.


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## Rick (Sep 9, 2014)

naoki said:


> That's a possibility (they used even higher EC fertilizer for testing the different media). But doesn't Sphagnum moss have even higher CEC?




??? Not all LECA and sphag created equal. 

For not having read the article, are they looking at leaf and root tissue concentrations (like in the Rodriquez paper)?


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## Rick (Sep 9, 2014)

naoki said:


> One of the chapter is published in a peer-reviewed journal (South African Journal of Plant and Soil 2007 24(3): 166-171), which is about the nutrients.



Trying to put this link back in with a possible correction on spelling since I was only getting errors when I tried to pull it up.

Still can't get it.


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## TyroneGenade (Sep 9, 2014)

You can download the entire thesis for free off the University of Stellenbosch website Naoki linked to: https://scholar.sun.ac.za/bitstream/handle/10019.1/3042/pienaar_study_2005.pdf?sequence=1


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## naoki (Sep 10, 2014)

Rick said:


> ??? Not all LECA and sphag created equal.
> 
> For not having read the article, are they looking at leaf and root tissue concentrations (like in the Rodriquez paper)?



No, they are interested in the growth over a year, so no tissue analyses.

Sorry for the wrong link, how about this?

http://www.tandfonline.com/doi/pdf/10.1080/02571862.2007.10634801

With LECA, they get about 50% mortality (while the mortality was close to 0 for the other types of media). This part isn't in the published paper (it is in the thesis). You are right, there appear to be a variation within sphag. I think they mentioned Chilean vs NZ.


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## gdupont (Oct 20, 2016)

naoki said:


> After couple advises here, I looked around additional scientific studies of Disa culture (hybrid with D. uniflora as the parent), and I found a pretty nice thesis here (scroll down to see the link to PDF):
> 
> https://scholar.sun.ac.za/handle/10019.1/3042?show=full
> 
> ...



Sorry to be dragging this post up from quite awhile ago... So, what kind of fertilizer is best for Disas, then? Could you distill this knowledge a bit more? Thanks!


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## NYEric (Oct 20, 2016)

Water.


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## TyroneGenade (Oct 20, 2016)

NYEric said:


> Water.



I was told "distilled water" but I suppose rain water is OK too. oke: The less fertilizer the better.

Anecdotally, regular sprayings with Seagrow work well. I tried this and it didn't kill the plants but the live sphagnum they were growing in wasn't happy about the Seagrow.


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## gdupont (Oct 20, 2016)

Yeah, I've just been using RO water, but I think it's going to need fertilizer at some point... And some people obviously use fertilizers for Disas.


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## naoki (Oct 20, 2016)

I'm not so successful with Disa, but here is a couple with both N sources:
Dyna-gro Grow has 4.4% NO3 and 2.6% NH4.
Dyna-gro Hi-N-Pro seems to be better with less phosphorous, but it is a bit more difficult to buy.
Grow More Orchid Urea Free has 12% NO3 and 8% NH4, but no Ca, Mg, and B. 
Jack's Orchid liquid 7-5-6 has 5% NO3 and 2% NH4.
Jack's Peat Lite 20-10-20 has 12% NO3 and 8% NH4, but no Ca.
I think I was using MSU + ammonium nitrate.


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## gdupont (Oct 20, 2016)

naoki said:


> I'm not so successful with Disa, but here is a couple with both N sources:
> Dyna-gro Grow has 4.4% NO3 and 2.6% NH4.
> Dyna-gro Hi-N-Pro seems to be better with less phosphorous, but it is a bit more difficult to buy.
> Grow More Orchid Urea Free has 12% NO3 and 8% NH4, but no Ca, Mg, and B.
> ...



Great, thanks for this breakdown! How much would you dilute the Dyna-gro Grow? In other words, how much should I add per gallon?


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## naoki (Oct 21, 2016)

I measured EC of Dyna-Gro Grow.
Base dH2O: 13.70 microS/cm
At 20ppmN of Dyna-Gro (0.286ml per a litter of water), I get 222 microS/cm.

So it raise the EC by 208.3 microS/cm. It terms of tsp, if you do 1/4 tsp per gallon, you'll get 23ppm N, which should give EC of 239.5 microS/cm, which seems to be close to what is recommended by Wally Orchard. So it should be good if your base water EC is close to 0.


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