[ In case you don't read the whole post - I ended this experiment after 5 weeks when all the roots on one of the plants rotted. And I mean ALL, see photo at the end. The other two plants weren't quite as bad, but they appeared to be heading the same way, so I stopped the experiment with all of them. As several others have found with their experiments (which I knew about and ignored), do NOT USE water culture, or use at your own risk! Despite my elaborate rationale, which I have left intact below, clearly this is not a good plan, or at least not the way I did it. Yes, Phalaenopsis are not aquatic. I should add that this experiment does not rule out the possibility that new roots would be better adapted for growth in water, but I elected to save my plants. ]
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| Photo from http://www.phals.net/honghenensis/honghenensis-in-situ |
I have had three Phalaenopsis hybrids for many years, and they have done fine in the usual mixed bark planting medium, but I recently decided to try them in water culture. I will report on how the plants do over time. I don't know how generally pure water culture will work for orchids - probably not well for most. Growing in inert media such as sponge rock, expanded clay, or charcoal seems to work fine for a wide range of epiphytic orchids, but the water/air/root dynamic under those conditions is much more like traditional media.
I got started with the idea of water culture due to one Phalaenopsis hybrid in my work office, where humidity is very low. I was growing it cased in a sealed pot sitting in a shallow bowl of water, hoping to keep local humidity up a bit, and as it grew aerial roots I started tucking their ends into the water hoping to keep it happy. The roots clearly loved being in the water - they grew fast and they looked fat and sassy and they were bright green. The plant thrived. Yes, it is a grocery store hybrid Phalaenopsis (i.e. only my friend Theresa is capable of killing it) and most of the plant is still in bark medium in a pot, but the idea germinated of tossing the pot and growing in a bowl of water.
Look at the roots in the in situ photo, photographed in situ in mountains in Burma growing low on the trunk of a tree (the roots are the silvery green ribbons plastered all over the bark). This species of Phalaenopsis has very few leaves and apparently does much of its photosynthesis with its roots. Most Phalaenopsis species have more leaves but they all have light-exposed greenish roots, and a few species are leafless or seasonally leafless. Their roots provide most or all of the photosynthesis. Growing Phalaenopsis mounted directly on tree bark is most natural, but it isn't convenient unless you happen to live in the right place or have a greenhouse and are willing to wet them every day.
Back at home with my test plants: the containers I am using for my full water culture trial are glass bowls that are approximately spherical with a slice off the top of the sphere. This sort of vase is relatively easy to find on-line - a search at [a certain large retailer named for a South American river] for "glass bowl vase" finds them readily. The idea is that the narrow mouth will support the plant and keep the humidity inside the container high and the clear sides will allow the roots to green up and become photosynthetic, which is the natural condition of Phalaenopsis plants in the wild. The broad leaves of the plant rest on top of the vase and the entire plant body and most of the roots are not immersed. The roots would never naturally grow under water, but keeping the water very shallow will hopefully keep them well aerated. The base of the plant stem is at least 5 cm from the water and it is dry. The root core presumably transports water up the leaves but the root velamen is dry to the touch above the water line. I will be surprised if I have a problem with stem rot as others have reported for their tests. The setup I am using would be harder to arrange for plants with different shapes, but for Phalaenopsis in the right sized bowl they just sit that way naturally.
I am using a rather small amount of deionized water in the bowl (about 2 cm deep) with a bit of complete fertilizer added (the kind designed for pure water - it has calcium and magnesium and all the trace elements in addition to all the usual stuff. Don't you just love that plants require molybdenum? What!?). Tap water is probably fine too as long as it doesn't have a lot of dissolved minerals. I dump the water out for a day or two once a week, as various sources on the web suggest - the idea is to inhibit too much bacterial and fungal growth and to mimic occasional dryness in nature.
The photo above is one of my plants, for which I am keeping a photographic record. This plant just came out of bark medium and you can see that most of the roots are bone white, with only a few green bits - the parts that were aerial when potted. Two weeks later, as I write this post, the roots are already getting a pale green blush - I will update or make a new post when the difference is more obvious. So far no roots have died.
As a side note, it is interesting that the natural plant (above) is growing "sideways" - from pictures and comments I have found on the web, this is usual for Phalaenopsis, and quite often they grow slanting downward or even completely upside down (how the seeds stick and germinate on the bottom of a branch I don't know). This explains why culture guides warn that you risk rot if you wet the growing crown of Phalaenopsis, yet natural rain doesn't present a problem. They don't grow right side up! Um well, we don't grow them right side up.
And ... experiment over because here are the roots after 5 weeks (I cut them off as they rotted one by one, but I stuck with it to the bitter end). You can't see the plant leaves above, but this is the same plant - I just moved it temporarily to rescue spaghnum moss and my experience is that it will recover without much trouble because it is a Phalaenopsis hybrid and they are tanks. If you look closely you can see one new root tip, which started while still in water culture.
Look at the roots in the in situ photo, photographed in situ in mountains in Burma growing low on the trunk of a tree (the roots are the silvery green ribbons plastered all over the bark). This species of Phalaenopsis has very few leaves and apparently does much of its photosynthesis with its roots. Most Phalaenopsis species have more leaves but they all have light-exposed greenish roots, and a few species are leafless or seasonally leafless. Their roots provide most or all of the photosynthesis. Growing Phalaenopsis mounted directly on tree bark is most natural, but it isn't convenient unless you happen to live in the right place or have a greenhouse and are willing to wet them every day.
Back at home with my test plants: the containers I am using for my full water culture trial are glass bowls that are approximately spherical with a slice off the top of the sphere. This sort of vase is relatively easy to find on-line - a search at [a certain large retailer named for a South American river] for "glass bowl vase" finds them readily. The idea is that the narrow mouth will support the plant and keep the humidity inside the container high and the clear sides will allow the roots to green up and become photosynthetic, which is the natural condition of Phalaenopsis plants in the wild. The broad leaves of the plant rest on top of the vase and the entire plant body and most of the roots are not immersed. The roots would never naturally grow under water, but keeping the water very shallow will hopefully keep them well aerated. The base of the plant stem is at least 5 cm from the water and it is dry. The root core presumably transports water up the leaves but the root velamen is dry to the touch above the water line. I will be surprised if I have a problem with stem rot as others have reported for their tests. The setup I am using would be harder to arrange for plants with different shapes, but for Phalaenopsis in the right sized bowl they just sit that way naturally.
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| Phalaenopsis unknown hybrid day 1 (5/11/2017) |
I am using a rather small amount of deionized water in the bowl (about 2 cm deep) with a bit of complete fertilizer added (the kind designed for pure water - it has calcium and magnesium and all the trace elements in addition to all the usual stuff. Don't you just love that plants require molybdenum? What!?). Tap water is probably fine too as long as it doesn't have a lot of dissolved minerals. I dump the water out for a day or two once a week, as various sources on the web suggest - the idea is to inhibit too much bacterial and fungal growth and to mimic occasional dryness in nature.
The photo above is one of my plants, for which I am keeping a photographic record. This plant just came out of bark medium and you can see that most of the roots are bone white, with only a few green bits - the parts that were aerial when potted. Two weeks later, as I write this post, the roots are already getting a pale green blush - I will update or make a new post when the difference is more obvious. So far no roots have died.
As a side note, it is interesting that the natural plant (above) is growing "sideways" - from pictures and comments I have found on the web, this is usual for Phalaenopsis, and quite often they grow slanting downward or even completely upside down (how the seeds stick and germinate on the bottom of a branch I don't know). This explains why culture guides warn that you risk rot if you wet the growing crown of Phalaenopsis, yet natural rain doesn't present a problem. They don't grow right side up! Um well, we don't grow them right side up.
And ... experiment over because here are the roots after 5 weeks (I cut them off as they rotted one by one, but I stuck with it to the bitter end). You can't see the plant leaves above, but this is the same plant - I just moved it temporarily to rescue spaghnum moss and my experience is that it will recover without much trouble because it is a Phalaenopsis hybrid and they are tanks. If you look closely you can see one new root tip, which started while still in water culture.
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| Same plant on 6/17/2017 |
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