Hey, Tindo. I haven't been here for a while because of school and being busy with work, but it is great to hear from you.
My successes with
Disa uniflora are very spotty to tell everyone the truth. It is not easy to pinpoint the problem sometimes.
After years of looking at photos of them in the wild, I have come to the conclusion to the following truths:
1. They are in actuality
lithophytes NOT true terrestrials just as I have suspected a long time ago.
In fact, how they really grow is usually in between rock crevices with moss growing out between the rock crevices. Their roots are growing in moss. They are found growing along stream banks or slow water run-offs/drip zones/splash zones near waterfalls.
2. They do NOT like it sopping wet around their roots, they like consistent even moisture. If the potting medium dries out too much, it will stress out A LOT. It can recover if you catch the plant wilted in time, but it will never look the same as before again.
I think the biggest problem lies here!
People are told they love water, and to a degree this is true. But the largest contributor to their quick demise is most likely overwatering NOT any kind of sensitivities to fungus.
3. They can tolerate some heat, but not a lot of it. The highest temperature they can handle is 85 F tops. Any higher for very lengthy periods of time and they show signs of heat stress until they eventually give up.
ONLY for
very short periods of time can they handle temperatures of 90 F to 95 F, but not if this is going to be a consistent ordeal. By brief periods of time I mean 1 - 2 days, and it cannot happen a lot. If the temperature reaches 90 F to 95 F in their growing area for 1 - 2 days, say, 4 times a month, for example, it can really be stressful for
Disa uniflora.
4. It doesn't take much to bloom
Disa uniflora. If you have a mature sized plant, and if they are cared for properly enough until mid to late spring rolls around, you will eventually see it bloom. These bloom like clockwork and there is no special trick to get them to bloom. This is one of the reasons why I actually love growing
Disa uniflora over
Disa tripetaloides or
Disa aurata.
5. They can grow very quickly asexually.
They grow plantlets via brittle fleshy stolons or near the base of the mother plants.
Disa uniflora, particularly, does not grow as fast as say,
Disa tripetaloides, but they grow quite quickly compared to say a Cattleya or a Phalaenopsis.
6. Do NOT grow these in full sun the closer you live to the equator! Sometimes you will see some websites that say they can grow in full sun; don't do it - not unless you live in places like the state of Washington where you might get away with this. They grow just fine in bright shade here in Los Angeles County.
7. The flowers are slightly fragrant.
8. The flowers last about 1 month if I'm not mistaken.
9.
Disa uniflora is not quite "uniflora", ("one flower"). One flowering inflorescence can put out up to 3 flowers.
10. They should be ideally watered with water that is relatively soft. Water that is too high in calcium carbonate is harmful to them. They do need some calcium in order to function properly, but the water should not contain too much of it.
I would say a dKH of about 2 dKH is fine in terms of water hardness.
For safe calcium concentrations I don't know, because I haven't actually measured for this yet.
In orchid hobby circles, dKH is not widely mentioned or discussed. Most people in the orchid hobby are used to the term "TDS", (TDS = total dissolved solids). The term TDS is too broad of a concept as it does not really specify what those "total dissolved solids" actually are. It is just a measure of how much "dissolved solids" are in the water irrespective of what those "dissolved solids" are and in what concentrations they are at in the water. If anybody still wants to know about TDS numbers that would be considered safe, I'd say about 10 - 11 ppm of TDS is fine.
Degrees k(c)arbonate hardness is far more precise as it is only concerned about the amount of carbonates present in the water.
There is a carbonate hardness test kit available for freshwater that you can easily purchase at any local fish shop.
Apparently there are also calcium test kits you can purchase at your local fish shop too! They are mostly marketed towards tropical reef hobbyists, but at least one company claims that their calcium test kits can also be used to test freshwater. That brand is Salifert.
11. They do not always drop tuberoids. Why they drop tuberoids is poorly understood at the moment.
12. The tuberoids are made from similar cells as those found on the orchid's roots and are therefore soft and delicate.
13. If you damage the tuberoid in any way shape or form, the likelihood that you will be able to successfully save it is very, very poor.
14. If you damage the growing shoot on top of a tuberoid, it is most likely done. You see, there is only
one growing shoot per tuberoid in the case of
Disa uniflora. Once this little shoot dies, the tuberoid almost always dies afterwards. It might take some time, but it usually happens this way.
NOTE: Not all Disas have tuberoids with only 1 growing shoot on top of it - do not overgeneralize. I know for a fact that
Disa thodei has
multiple shoots per tuberoid.
15.
They are NOT sensitive to fungus. You don't need to have a fungicide on hand 24/7. They are not that prone to fungal attacks. They look like they are because their roots are rotting out probably due to improper care, but in reality, fungus is usually NOT the cause of their demise.
This is a classic case of
correlation not necessarily being causation. Just because 2 factors are in correlation with one another, doesn't necessarily mean that one factor is causing the effects of the other factor. Think science people, and remember correlation does not necessarily mean causation!!!
16. They do not like to have their roots sitting in large bodies of water regardless of how aerated that body of water is. They might look fine for the first few weeks, but what eventually happens is this...
Their roots will look excellent, but the vegetative portions of the plant will rot out due to damping out.
17.
Disa uniflora is self fertile. It is possible to use pollinia from one flower and rub the pollinia onto the stigmatic surface of the same flower or other flowers from the same plant and get fertile seeds.
18. If stored properly, fertile
Disa uniflora seeds can remain viable for up to 1 year. The number of seeds that can remain viable within that 1 year period has the possibility of dropping dramatically in that time frame.
Now the following things I haven't confirmed yet, so at this point it is just a
hypothesis that is based on some observations I have noticed about certain parts of South Africa and some reading:
1. Disas
might be sensitive to high phosphorous levels. I have been starting to read on certain websites that plants such as some Proteas are sensitive to high phosphorous levels.
Q: Well Philip, we are talking about Disas, why are you all of a sudden talking about a totally unrelated plant such as Proteas?
A: Because many species of Proteas originate from South Africa, and some species of Protea have been observed growing in areas where some Disas are growing as well.
Therefore, if some species of Proteas are found growing in close proximity of some species of Disas, and since some Proteas are sensitive to high phosphorous content in the soil, then it is quite possible that some Disa species may also be sensitive to high phosphorous.
2. Disas
might enjoy adequate amounts of iron. I have noticed that
some of the rocks, (not all), in South Africa have an orangey tint to them. That orangey tint is usually a sign of ferrous oxide/iron oxide, (aka rust). I do not know if the rocks that
Disa unflora grows between may contain traces of iron or not, but since the rocks are metamorphic igneous type rocks, (the rocks seem to be some sort of quartzite or granite with high quartz content), iron could be a possible impurity that gets leached out in small quantities.
3. Some Disas might favor potassium over nitrogen or phosphorous. I have noticed that some of the rocks that
Disa unflora grow between have a pinkish tint to them. That is usually a sign of potassium being present in the rocks and may be leaching out in small quantities.
One reason I mention potassium is that Disas can produce tuberoids.
Guess what people...
There is a very popular food that a lot of people like to eat that is in the form of a tuber...
Yeah, you guys probably know where I'm going with this.
POTATOES!
Potatoes are known to contain a high level of potassium.
Now that I am in the medical field, this is not conjecture, this is a known fact! For patients whose lab tests show that they have dangerously high levels of potassium in their blood, one of the foods we tell them not to eat are potatoes.
Here's one piece of evidence for potatoes containing high amounts of potassium:
"High-potassium foods (more than 200 mg per serving):
1 medium baked potato, with skin (925 mg)
1 baked medium sweet potato, with skin (450 mg)"
(
https://www.drugs.com/cg/potassium-c...oods-list.html)
So, I can only assume that the Disa tuberoids, (aka Disa potatoes - which is literally what they superficially kind of look like), are also storage organs for certain things such as the nutrient potassium as well as sugars.
In the past, I had suspected that Disa tuberoids were storing potassium, but this was difficult to make a connection to, and I have occasionally been highly criticized for this hypothesis, but now, I have a more solid base to stand on without having to destroy a Disa potato to find out the nutrient contents of that potato, (although this can be arranged if I end up with high enough quantities of
Disa uniflora potatoes to send to a lab that can tell me what exactly it is that these Disa potatoes are storing).
4. Of what I have observed in photos online of
Disa uniflora growing in-situ, there is practically very little by way of any rotting vegetative material present around
Disa uniflora, which I take to mean that nitrogen may not be available in high quantities.
5. The need for using humic acid when watering is up in the air. Some of the waters that feed
Disa uniflora contains humic acid. Whether it is advantageous or not to the growing of
Disa uniflora is not well understood nor presently known. I can only assume that any advantage humic acid has for growing
Disa uniflora may actually be very minimal.
I do not have very many specific literature on hand to cite from. I did not bother to log my sources of information. Nobody other than you have actually asked me this. Some of the information was gathered from observations and personal experiences from growing these orchids.
I do have three source materials you can read from for some information:
1. Crous, H., & Duncan, G. (2006). Grow Disas: A Practical Guide to the Cultivation and Propagation of Evergreen and Deciduous Disa Species of Southern Africa. Claremont, South Africa: South African National Biodiversity Institute, Kirstenbosch.
2. Fey, M. V. (2010). Soils of South Africa. Cambridge: Cambridge University Press.
3. Velde, B. (1992). Introduction to Clay Minerals: Chemistry, Origins, Uses, and Environmental Significance. London: Chapman & Hall.
I also have these images to offer of
Disa uniflora growing in-situ:
https://upload.wikimedia.org/wikiped...eton_Gorge.JPG
http://1.bp.blogspot.com/-BTma6FVTBy...0/IMG_1625.JPG
http://www.ilovecapetown.com/Photos1...n_and_Disa.JPG
https://www.awoltours.co.za/wp-conte...s/P3030253.jpg
http://2.bp.blogspot.com/-iNd48Aksi4...0/IMG_1629.JPG
Notice how the photos almost always show
Disa uniflora growing out from between the rocks.
Linear Mode
