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Semi Hyro, self watering, leca?

Discussion in 'Orchid Culture' started by Terry Mann, Dec 2, 2018.

  1. Terry Mann

    Terry Mann New Member

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    After some research, I purchased some self watering pots on Amazon in various sizes and some leca. The pots use a cotton wick to draw the water, fertilizer up to the leca in an inserted pot. A sound principal, maybe? I chose a few Phals to try this system out. It has only been a couple of days but I'm apprehensive already. Both the inner and outer plastic pots are opaque the inner pot has some slots for ventilation and does not sit in the water. Within 24 hours, I noticed that the top leca was dry and upon checking, the water in the reservoir has not dropped. All of these Phals are in flower or bud BTW. I'm almost ready to repot the whole lot in Orchiadta bark. I have not unpotted any of them to see if the leca has drawn any water up the wick. One of the plants had pretty bad root loss, discovered at unpotting, but also has 2 flower spikes, this plant had been in bark. I wouldn't say that the media was bad but I had some moss in the mix and I had not added holes to the sides of the clear pot. I think that algae smothered the roots.
    Either way, I'm not encouraged in my experiment
     
  2. KellyW

    KellyW Orchid wonk Staff Member Supporting Member

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    Terry, I can't speak about semi-hydro or self watering since I haven't tried it. However, I have used LECA for many years as a substitute for bark and just water as I would with bark. It doesn't deteriorate, creates less demand for nitrogen and can be reused. If you abandon the self-watering perhaps you could continue to use the LECA and water normally for an experiment in your conditions.
    Good luck.
     
  3. xmpraedicta

    xmpraedicta Prairie angraecoid nut Supporting Member

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    After seeing a facebook post on this method of growing, I tried a poor-man's version of what you're describing; a wick sucked up water from a reservoir below and moistens the media, which was mainly perlite, some cork, and coco husk.

    The plant did fine for about 2 years, and then started developing fungal leaf spots one winter. I probably wasn't changing the water often enough, and the plant was abandoned. I suspect it's a good technique for warm/dry climates, which favor evaporation. Not so great during cooler winter weather.
    [​IMG]
     
  4. Terry Mann

    Terry Mann New Member

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    So, do you feel that the inner pot can be in contact with the water?
     
  5. Ray

    Ray Orchid Iconoclast Supporting Member

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    Terry, it seems to me that there are several questions in your posts, and that it looks like you're trying to mix two different growing techniques.

    Semi-hydroponics involves the use of an inert medium (usually LECA) in constant contact with a reservoir of nutrient solution. Most of the time, that is created by the use of a single pot with a closed bottom, into which two, 1/4" holes have been made in the sidewall, about an inch up from the bottom. The "pebbles" sitting in the reservoir will be saturated and will wick moisture upward. There is an opposing force primarily at the top - evaporation - taking water away from the pebbles, creating a moisture gradient, bottom-up. I suspect that your use of a wick simply provides insufficient moisture in the first place, and that any additional holes or slots in the pot enhances evaporation so much that it negates the wicking capacity of the LECA.

    The second part of this relates to the facts behind root growth and function. As roots grow, they "tailor" themselves, on a cellular level, to function optimally in the environment into which they are growing. Once those cells have grown, they cannot change. When you move a plant from one potting medium into another, you are changing that environment, so the existing roots are no longer optimal, and will begin to fail. That is why the best time to repot a plant is just when brand new roots are emerging from the base of the plant - those new roots will grow optimized to the new environment and support the plant as the old roots fade away. How rapidly they old ones fail is determined by the degree of difference between old and new conditions.

    Back to evaporation for a moment - and this applies to S/H culture as well as your wick/sphagnum setup - I suspect you're poisoning your plant.

    Referring back to the reservoir at the bottom and wicking moisture upward, be aware that anything dissolved in that liquid - fertilizer, whatever is in your water, and plant wastes - is also wicked up. As the water evaporates, they precipitate. Continue that process and they buildup eventually reaches a concentration that is toxic to the plant. In the case of S/H culture, we prevent-, or at least greatly forestall that by flooding the pot at each watering, filling the pot with dilute nutrient solution and letting it drain down to the holes. That achieves flushing the medium, saturating it, and refreshing the chemistry of the liquid in the reservoir. Folks who only "top up" the reservoir eventually notice an increase in ailments and weakening of their plants, as have you.

    A final thought: you wrote of your phalaenopsis in "cooler, winter weather". Phalaenopsis, for the most part, are "hot growers", rarely seeing below the mid-70's in nature, and often triple digits. While they are tolerant of the somewhat reduced temperatures we prefer, they dislike a chill, especially if the roots are moist.
     
  6. Terry Mann

    Terry Mann New Member

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    I'm not wicking into sphagnum but leca, all alone nothing else. The root loss I experienced was in non-self watering bark/sphagnum/perlite media watered every 4 days in clear plastic pots. The roots looked great until algae began to be seen in the pot.
    I don't recall saying anything about cooler, winter weather, my grow space is not hot, about 73-74 degrees F.
    I will still flush with R.O.D.I. water regularly. This present self-watering- leca system has not even been used a week yet.
     
  7. Ray

    Ray Orchid Iconoclast Supporting Member

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    Sorry, I mentally combined your post and that of xmpraedicta!

    I still feel that while the "wick" pot might be fine for soil, it will simply not transfer enough moisture for most orchid media. I hope you prove me wrong!