Semi-hydroponic for growing orchids
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Semi-hydroponic(s)™ or semi-hydro, semi hydro, semi-hydro culture, s/h. Form of passive hydroponics. A method of growing plants without soil. Instead a practically inert wicking medium transports water and fertilizer to the roots by capillary action. Medium contains a multitude of free air spaces and thus delivers oxygen to the roots.
Even conventional orchid culture can be considered hydroponic in nature. The medium is there primarily for mechanical support, and provides little, if any, nutrition to the plant, that being provided by the nutrient solutions used.
Semi-hydroponic(s)TM popularized and named by Ray Barkalow ( First Rays Orchids - [1] ) has become a popular method for growing orchids both out- and indoors.
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[edit] Planting
Orchids can be planted in any container (not glass) with no drainage holes at the bottom but a few extra holes 3-5 cm up at the sides of the pot. The idea is to provide a water reservoir at the bottom of the container from which the medium wicks moisture to the roots.
[edit] Popular media
LECA (Lightweight Expanded Clay Aggregate) - expanded/fired clay pellets or clay pebbles , perlite, vermiculite, gravel, charcoal, rockwool, coconut husk chips and their combinations.Diatomite is expanded silicaseous earth, good as a component and beautiful too
[edit] Water
Medium is flushed with tepid water solution when reservoir is nearly empty. Translucent pot may help to see when it is.
[edit] Fertilizer
Orchids are fertilized with 1/2 or 1/4 of recommended strength of balanced inorganic fertilizer with every watering. Container is flushed with plain water every month to prevent harmful salt build up.
[edit] Conversion from conventional culture to semi-hydroponic
Medium is rinsed and soaked overnight. The plant is removed from the old pot and old medium is thoroughly removed from the roots. Rotten roots are cut away and overlong roots are trimmed. All the roots are thoroughly washed in lukewarm water. Some new medium is arranged at the bottom of the new container. The plant is accommodated and more new medium is put around, the pot is gently shaken, more media is put in, more shaking and so on. The pot is flushed with tepid water. The Orchid is placed in the shade with no fertilizer for the following month.
[edit] Transplantation
from semi-hydro to semi-hydro is simply transferring the plant with the medium to a new pot and filling with more presoaked medium.
[edit] Which orchids can be grown?
Most popular orchids will more or less thrive in semi-hydro culture: Paphiopedilums, Phragmipediums, Masdevallias, Phalaenopsis, Cattleyas, Cymbidiums, Oncidiums, Dendrobiums, Epidendrums, Miltoniopsis, Pleurothallids and Zygopetalums.
Exceptions would be very big or "thirsty" plants or those whose roots must dry sometimes completely and even those that require dry rest like Dendrobium nobile.
[edit] Advantages of semi-hydro
Its simplicity and effectiveness. No guessing about watering and fertilizing, no media decomposition, practically no root rot, healthy plants, fine blooming, no moving parts, low cost, reusable media. In hot and dry environments, semi-hyrdoponics may help, since the roots stay in a high humidity chamber with some air flow.
[edit] Disadvantages
The main disadvantage can sometimes be the need of more frequent watering, especially when plants begin to fill their pots, are big or otherwise demand lots of water. Obviously, a bigger water pot/reservoir may help (or side holes higher up on the pot). If the sides of the translucent containers receive enough light exposure then algae will grow on the outer layer of the potting media. This is mainly an aesthetic concern and not a big problem indoors. If the medium consists of small expanded clay pebbles and the plant is newly established then tipping it over may cause the spilling of said medium and plant.
[edit] Etymology
- hydroponic - Greek hydro - water, ponic - work, exertion, tiredness, also: pain - "working water", "water work" eg. culture without soil
[edit] External links
- First Rays Orchids http://www.firstrays.com/semi-hydro.htm
- Useful tips http://www.growinhydro.com/7155.html
