Shiva, I grow and sell Disas. In fact, I'm the exclusive Disa distributor for North America, Central America and the Caribbean for Alba Labs in South Africa. Their plants are not all registered with the RHS however. Many have "commercial" clonal names only. However, I also grow properly named Disas, species and hybrids. I have been working for the past 3 or 4 years at getting just the correct conditions to reliably grow, bloom and rebloom these awesome plants. It's been a very costly, uphill battle. However, I've been sure to learn the lessons of my failures and not make them again. This year I learned that in my area of Canada at least, we have too many dark, overcast days in November and December to keep most Disas healthy, despite the fact that they do naturally go semi-dormant in the winter. It seems that they don't want to go as dormant as my low light levels push them! So, once again, I've lost a lot of plants; but, I will begin supplementing the light soon to halt the downward trend in the general health of the plants. By late January, even though it's cold and the days are still short, the sun shines most days and the Disas REALLY wake up and begin growing like crazy again.
Anyway, I will have Disas for sale (definately seedlings and probably some larger NBS plants), by March or so. I want to hold off selling any until I see that they've made it through the worst of this dark winter and that they have started to put on vigorous growth again. Then, I can sell them.
Please feel free to keep in touch with me about this. I suggest that you send me a PM in late February to ask how things are coming along.
BTW: The most frustrating part of growing Disas is that often you get a plant that does supremely well for you and you come to just love it! Then, it finishes blooming and promptly dies without producing any new growths. This is because it has not produced any tubers....and of course, once a rosette has bloomed, that part of the plant dies. So, your only chance of retaining that clone is to have satelite propagations coming up from tubers that have formed on the mother plant's roots. Also, occasionally a plant will send out stolons as well as, or instead of, tubers. These are also good for multiplying a plant and keeping it going from year to year. I've asked MANY people about the tricks used to get the plants to reliably produce tubers each year, ensuring the long term survival of the plants. Some have thrown up their hands and not had an answer. Some have had an idea and shared it with me. My conclusion is that tuber formation, while vital to the plant's long-term survival, is not necessarily vital to the species survival. Many plants "chose" to sacrifice themselves and put all their strength into blooming and hopefully, producing seeds instead of putting their strength into tuber formation to extend their own life. So, to encourage tuber production, one must find that balance between giving the plant all it needs to grow and bloom spectacularly; but, also not quite enough to convince the plant that it can do a really wonderful job of producing gobs of seed and therefore, IT does not need to survive.
The best way to increase the chances of tuber formation seems to be to keep the roots cool and to stop feeding once the flower spike is well under way. Also, don't begin feeding again until you see new growth emerging from the pot....usually during, or sometimes, after flowering, next to the old, dying mother plant.
The coolness simply satisfies the naturally evolved needs of the plant which comes from generations of growing in a cold water environment. In nature, even though the flowers and foliage may be quite warm in the summer sun, the roots are constantly kept cool in, or very near, cold water mountain streams.
The lack of food beginning when the buds appear will allow the plant to use up all the fertilizer residue still in the potting mix and if you've been feeding very lightly; but, often during the whole growth cycle up until then, what's left in the pot when you stop feeding will produce and sustain a beautiful blooming. However, the diminishing nutrients at a time just prior to normal seed production, will cause the plant to "rethink" the idea of sacrificing itself in favour of producing seeds. Instead, using the chlorophyl in it's leaves, it will use sunlight, water and CO2 to make simple sugars which need to be stored in tubers attached to it's roots. So, as well as satisfying the plant's physiological needs by keeping the roots cool, you actually trigger tuber formation by starving the plant of the nutrient elements required for growth, at a critical time in it's life cycle and this encourages sugars to be formed instead, which are then stored in root tubers as a way to fuel future growth, which is what we want!
I've got a few hundred seedlings and plants at the moment. I'm sure to have some ready for release in a few months.
Here are 3 different Disa unifloras that bloomed for me last summer.
I know, I know, I don't have many slippers to show, but they're coming. Lots of small plants that need to grow still.
