Life of a Disa
This is a somewhat fanciful story of what happens from the time a butterfly pollinates a Disa flower to the time the new plant dies. This is not strictly scientific but is based upon my own personal observations. This story is also heavily influenced by what I see in the greenhouse. Plants growing in the wild are a whole new ballgame. I don't have wildfires in the greenhouse and can usually provide enough light for a plant to mature in 3 years or less as opposed to the wild where maturation may take a lot longer than 3 years. My purpose for presenting this narrative is to give you a little better idea of what is going on with the plant at the various stages of it's life cycle so that you don't throw the plant out when it seems to die after flowering. This story is based on the D. uniflora species and it's hybrids. D. uniflora is only one of over 200 species of Disas and some require very different growing conditions. Most plants available from me will pretty much follow this scenario. (if you can improve some part of the story, email me. Heck, I'm still learning!)
Viable seed is produced in nature when a butterfly carries pollen from one plant that it visited in search of nectar to another plant. The pollen is deposited on the stigmatic surface of the second plant and fertilization occurs. The area of the stalk immediately behind the flower is really the ovary of the flower. This section starts to swell after a week or so and as the seed swells and matures, the ovary swells and firms up. In the greenhouse, fertilization is normally done with a toothpick. Pollen is attached to a sticky pad located on either side and above the stigmatic surface. This readily clings to a toothpick and can then be transferred to a neighboring plant. Since Disa uniflora hybrids don't collapse after you remove the pollen, One can remove the pollen and store it in the refrigerator for use when desired and still enjoy the flower .About 40 days after fertilization, the seed pod will burst and disperse the seed over the surrounding area. In this area, that seed which lands in a favorable area, swells as it absorbs water and will slowly start to develop. In nature, this happens during the late summer and early fall of the year. The embryo grows quickly and within a month or two is already a small plant. The way a Disa probably survives it's first winter in the wild is by being either big enough to form a small tuber or storage organ or by finding a sheltered location where it won't be subjected to freezing temperatures during that time. In our artificial conditions, the seedpod is normally harvested just before the pod is ready to burst. The surface of the pod is then sterilized with a bleach solution and then sowed under sterile conditions on an agar surface containing all the nutrients necessary to have the seed germinate and start to grow. Supposedly, you can sow the Disa seed on a boiled sphagnum moss bed and the seed will develop and grow. Mike Harrison at Acme Orchids in Ft. Bragg has done this for a number of his crosses but I have had no luck with that procedure to date. If anyone has successfully done seed this way, I would sure like to hear about how they do it.
During the second year of growth in our greenhouse conditions, a number of things can happen. The plant can develop a strong tuber and if it does so, it will certainly flower during the third year. The plant could also put most of it's energy into producing a flower stalk. If it does, the plant has a much reduced chance of surviving. The plant might also produce a number of offshoots. These are genetically identical to the parent plant and are produced by vegetative reproduction. The fact that we have no way of predicting what a plant will do during the second year makes growing Disas unpredictable. If I take a flask of Phals. and pot them out and put them in the greenhouse and treat them the same, I would be willing to bet that most of them could be made to bloom at the same time. Only a fool would make a similar bet with a flask of Disas. Now, what can be done to make the cycle more predictable?
I think that the ideal situation is when you allow the plant to slowly mature and put most of it's energy into producing a big fat tuber during the second year. If you do so, you are going to get a nice bloom the third year and probably a number of offshoots. The number and size of the offshoots is also an interesting thing. If you allow the plant to mature the second year and bloom the third year, and assuming the plant is happy, you will get at least one strong offshoot which will also bloom the following year and so on, and so on....... The smaller offshoots may take two years to bloom and are also dependent on how happy they are. What I'm trying to say, is that if you don't try to force your plants to bloom the second year, you will be much better off in the long run with your plants.
What happens after a plant blooms? With most orchids, nothing. They continue to grow and bloom and get bigger and stronger. With Disas, however, it's tap city, all she wrote, the big sleep. You can't do anything about it so you might as well live with it. If you have provided a happy environment for your plant, once the bloom starts to die, you can clip the flower and leave as much of the flower stalk as remains green. Don't throw the plant away at this time but continue to water like normal. Hopefully, while the plant is flowering, you will notice some small green new plants developing around the base of the plant. These are the offshoots and you want them to get as big as possible before you transplant them to a new pot. While the offshoots may appear during or even before the plant blooms, some hybrids take a long time to produce the offshoots. Don't give up on them. Let them stay on the bench as long as the flowered plant stays green. I've even had some offshoots develop after there was nothing left of the original plant but dried brown leaves.
Because of this cycle where a plant develops a nice tuber and then puts out a flower spike, you will notice that a lot of your Disas will bloom for you every other year. You want them to bloom every year, you say. Well the way to do that is by growing under optimal conditions that produce a lot of offshoots. If you make the plant happy, you will have 2 to 8 offshoots produced per mature plant each year. This year I had a uniflora that had over 30 offshoots. In a situation like this, there will usually be a few of the new offshoots that also develop a tuber. Pot them up individually and soon you will have more plants than you can handle. The best way to produce offshoots is by overpotting in net baskets. This forces you to give the plants individual space and they seem to love it.