Disa are pretty difficult to grow. I recommend visiting the areas where Disa grow, since you're in South Africa, and start writing detailed notes.
Questions to ask yourself are:
1. What are the specific habitats they grow in? (I recommend taking lots and lots and lots of photos. Take photos of some things you would never think about like the surrounding area where the plants are growing, the areas where the plants are growing themselves, close-ups of soil/rock types, close-ups of what the roots are growing in, take photos of the plants themselves, paying close attention to their growth habits. Don't just take pretty pictures of the flowers, every Disa grower around the world has seen a ton of pretty photos of the flowers themselves - that's nice, but from my personal experience it will not help you a ton.)
2. How are they growing? (I recommend taking detailed notes, leave no stones unturned. Even the most seemingly insignificant details, write those things down.)
3. In regards to the water they receive, what is the water chemistry like?
Hildegard Crous and Graham Duncan wrote a book called "Grow Disas", in it there is a rather short section on water chemistry from the areas that stream side Disas naturally grow (pages 40 - 41, for those who either own the book or those who wish to eventually get the book). There is a photo of a fancy pH meter that reads that the water is very acidic, (pH 3.5), along the streams some of the stream side Disas grow in, but I don't think this low of a pH is necessary to grow a good Disa. Since you're in South Africa, maybe make a trip one day when you're free to where they grow and measure the pH, calcium carbonate levels, magnesium levels, iron levels, zinc levels, nitrogen levels, potassium levels, phosphorous levels, and total dissolved solid levels of the water and find out what they really are. Chances are the mineral and nutrient levels might be "low", but what are the actual numeric values of the mineral content of the water? The water is most likely not nutrient deficient, otherwise no plants would be able to grow there. I have reason to believe that the nutrient content generally goes like so:
* Nitrogen, (N), is the lowest in concentration - in fact, I think it's anywhere around 0 ppm - 3 ppm, (this is the N in the N-P-K ratio). Again, I'm not certain of this, because there are no numerical data to support my hypothesis, but I think it is pretty close to what it may be.
* I have reason to believe that phosphorous,(P), is second lowest in nutrient concentration (this is the P in the N-P-K ratio).
* I also hypothesize that potassium, (K), is most likely the nutrient with the highest concentration (this is the K in the N-P-K ratio). I'm basing this off of what I read could be the mineral content of some of the rocks in that area, (I read a pedology and a mineralogy book - what head spinners, [for me]).
* Macronutrients such as calcium carbonate, (CaCO3), is probably low, along with magnesium. How low, I'm not too sure about, but I'm almost positive they are present, otherwise the plants will quickly show you outward signs of a calcium or magnesium deficiency
* I think the iron concentration is highest of the micronutrients, along with zinc
* I also think the TDS levels are low, maybe somewhere around 11 ppm - 20 ppm. These numerical values are guesses, and not supported by actual hard data. They are based on informally written accounts of the TDS values being low. Other than the author of the book "Growing Disas" mentioning that the TDS of the water is low in the wild, there is no actual hard numerical data readily available to support this without a shadow of a doubt.
4. What kind of rocks are they growing in? (Yes, the stream side Disas do not grow in dirt, they actually grow out from between the crevices of rocks. Many Disa growers out there have also heard of Table Mountain Sandstone, but this actually means very little, [to me anyways]. If I were you, I'd take a few rock samples and send them to a lab for testing and identification. If you do send the rock samples to a lab, make sure the rock heads speak to you in terms that are not too technical so you can understand what it means to you.)
5. Just how moist are the roots getting? (A few words about this…we've all heard they grow wet - this is not exactly accurate, I tested this out, they do not grow wet, they seem to grow consistently moist or something of this nature. I'm not 100% sure what the moisture level they like is because it's expensive to fly myself to South Africa and see for myself! All I know is that they don't like it sopping wet - they rot out very quickly if it is sopping wet. So check out just how wet it is in the root zone, not the surrounding areas; the roots are the ones getting the moisture so check there, not anywhere else. It doesn't matter much that they grow along streams, waterfalls, and drip zones, Disa growers around the world know this already, that's not the mystery; the amount of moisture around the roots will be different from the surrounding areas - this is the mystery.)
6. What are the roots growing in? (I think it's decomposing plant debris, because everywhere I read, it just says that the roots are amongst fibrous material.)
7. Get a good quality light meter, and measure the light levels of where they grow in the wild. Full sun for South Africa is not the same as full sun in Los Angeles, CA - for example.)
8. Get an outdoors thermometer and take some readings of the ambient air temperature during the morning, the midday, afternoons, and evenings. Then, try measuring the temperature during different seasons of the year.
Get a water thermometer and measure the temperature of the water.
That's what I recommend to you as a person who'd like to learn how to grow Disas who is already in the country they natively grow in.
There is much more to growing Disas than this, one day I might post a general guideline about how to grow them right once I figure out how to grow them right.
Btw, there is a reason why there is a high level of endemism with Disas in South Africa. What does this mean? Not every single Disa grows exactly like one another. Get this out of your head right now if you're gonna try to grow Disas. Treat each species of Disa very, very different from one another. Disa aurata does not grow exactly the same way as Disa tripetaloides does, neither does Disa uniflora grow the same way that either Disa aurata or Disa tripetaloides do, and Disa cardinalis is even more different than the other 3 Disas. I can keep going on-and-on about how different each species is, but I think you get it.
If I had to recommend a species of Disa for you to grow easily, try growing Disa bracteata. This will be the easiest Disa to grow by far, and they are still a bit of a challenge.
Habenarias are a whole different story.
Try growing Cynorkis, Stenoglottis spp., or Bonatea instead. Some of them are also native to South Africa. These should be easier to grow.
__________________
Philip
Last edited by King_of_orchid_growing:); 11-28-2014 at 12:16 PM..
|