Semi-hydroponics is a system developed by a man in Pennsylvania by the name of Ray. His website is here.
It is a passive form of hydroponics and is considered semi-hydro because the entire root mass is not submerged in water. It is a set up where you have a hydroponic material such as hydroton, which can be found in any hydroponic store, that is placed inside a container that has holes drilled roughly 1/4-1/3 of the pots height from the bottom so that it creates a reservoir. It is this reservoir that the roots will reach for and during this time, the hydroton "wicks" water from the reservoir upwards so that the roots higher up get the moisture they need, too.
It has been reported that just about any plant can grow in s/h. Even succulents and cacti have been reported to thrive in such a condition. How is this possible? It is because of the physiology of the roots that develop after you put the plant into the s/h set up. Some call them water roots, but the roots that grow in the s/h conditions are grown being use to that condition-- the higher moisture/humidity, the openness of the medium and the constant weak availability of fertilizer.
So, if you want to put a plant from soil into s/h, it is important to time it properly so that your plant does not suffer. Because its current roots are soil roots, they will likely die away once in s/h. Do not worry yourself over this as most plants have not only the ability to quickly replace those roots, but the mere act of repotting stimulates root growth. However, it is important to choose your plant carefully-- it must be vibrant and healthy and in some cases, such as orchids, must be actively growing new roots. This is very important! Plants like orchids will suffer the loss of their roots and if they're not in there cycle where they are growing roots, you may lose the plant. No new roots? Have patience and look for a different plant that is actively growing new roots.
How is this all done?
First, choose your plant. Have it ready and keep it well watered (not drowning) as this will make them acclimate a bit better to the switch. Several days before (3-7 days) get your hydroton or similar medium and soak it. Every day or even several times a day, wash out the old water and soak again. The water will likely be dark, reddish brown. This is the dust coming off the medium. It must be washed away as most roots simply don't like the muck it creates. By washing it several times with a good soak, you should have clean medium soon. Also, by soaking it, you make available more water for evaporation for the initial few days of your plant's new home.
Once you've noticed the water running clean with your hydroton, it is time to plant your plant. Bring the plant to a sink or hose or tub where you can freely wash off soil and organic matter. It is important to get rid of as much soil as possible. Many roots will cling to things such as perlite or charcoal. Don't pull this off if it doesn't come off with a gentle tug. This stuff isn't going to break down like organics will so if it doesn't come off, its ok to leave it on for now. But wash off as much as you possibly can.
For this tutorial, I've chosen a mini phalaenopsis that is currently in bloom (its ok to repot orchid in bloom!) that is pushing new root buds as well as bud on the existing roots. *Note about orchids, if the orchid was grown in heavy moss and kept moist, often the plant will acclimate well to s/h and may even retain its original roots* In the above photo, you can see my plant in its moss, its new pot and its already cleaned and soaked medium.
Next step is to drill two hole, roughly a 1/4 to 1/2 in apart from one another roughly 1/4th to 1/3rd of the height of the pot from the pots bottom. You are creating the space where the reservoir will be. I use a dremel to do this. Quick and easy. The drill bit is less than a 1/4 inch.
Next the drilling-- you can see how close the holes are. Hydroton and other similar mediums are roughly a uniform size. The reason for the two holes side-by-side? If one gets plugged, the hydroton that is blocking it will keep the other one from getting plugged, too.
Now the pot is ready for the hydroton.
I give the hydroton one final rinse before I use it in its new home. Be sure to really swish it around. This stuff has a way of releasing more dust as time goes by and giving it that last wash will give you peace of mind that it is in fact clean.
Next you prepare the plant. Here is my orchid in its moss.
*Note about keeping things clean* One of the best things about s/h is how clean you can keep things-- and certain plants, like orchids love to be clean! Most because of the potential for viruses and rot. So I have a mixture of water and Physan 20 on hand to spray down the plant, its roots, and all the things, including tools, that will touch it. Physan is also a good algaecide. I found mine on ebay for those who do not have it available in stores. Remove any and all organic matter from you plants roots and as you do, spray it down now and then with physan or similar disinfectants.
During this time, you must also inspect the roots and remove any dead or rotting/infected roots. Always use very sharp and clean tools for this. For orchids in particular, anything that is squishy, black, soft brown or that has lost its vellum (the fleshy outer part of the root) should be removed. The wire root on the inside of the vellum is useless without its fleshy outer part.
Once that is done, I give the roots a good wash again to get even more organics off the roots. Be careful with this-- many plants, including this phal, [i]do not like cold water[/i] or sudden changes in temps. Do be careful and test the water before you wash with it.
I then will spray it with physan again to completely drench the roots.
Here is my plant-- trimmed and cleaned and ready for its new home in s/h.
Fill up your new pot about half way up with hydroton.
Place the plant any way you'd like and spread the roots out so that they won't create dead spaces. Some dead space is ok but you want to fill in all areas as best as you can. I spread the roots out to the edges of the pot to give loads of room and so I can keep an eye on their health, as the pot is clear plastic.
Fill in the rest of the pot and tap the sides and bottom occasionally to get as much of the dead spaced as filled as possible.
Here are some of the roots that will give me an idea of the plants root system health.
And here is the plant in the end. But before it heads to the shelf, it needs its first good drink.
I use a weak fertilizer in my watering schedule because there are no organics in this system. Therefore you need to provide the food yourself. S/H can be messy because you must fill the pot to the top and let the excess run off. This is done so all the roots get a good drink and it refreshes the reservoir with fresh water, which can become problematic if weeks do by without new water. So when you do water, be prepared to catch the excess. Here's the new orchid doing its thing into the sink :lol:
And thats pretty much it. I'll edit this as I can with new/better/more concise info when i have time. But for now, the baby is awake and I gatta run!