How to Transfer Orchids to Semi Hydroponics in Leca Pebbles

Hydroponics is a water system (hydro=water) that substitutes soil for water. Since orchids don’t receive their nutrients from the soil but from the air currents and water droplets, they can transition to water culture without major problems.

Basically, in hydroponics, the roots are moist all the time, with little to no drying out periods. For constant moisture to occur, the potting medium needs to be filled with leca beads. 

Cattleya Orchid

What’s the difference between full water culture, semi water culture and hydroponics?

In semi water culture and full water culture there is a drying out time. In semi hydroponics, there is not. Another difference is that in SWC and FWC there is no potting medium whatsoever. It’s plain air. There are no leca beads, pebbles, gravel… nothing. The roots are exposed in a glass vase and you can see them clearly.

Water is added in intervals, and the level differentiates between 2/3 with semi-water culture and 1/3 for full water culture.

The time the water remains in the vase also varies: 2 days straight for the semi-water culture and 5 days straight for full water culture. Note that the roots need a period to rest in between watering. This does not occur with semi hydroponics.

If you want more information on what full water culture is and how to transfer your orchid to FWC, then check out this article.

How do I know when to choose Semi Hydroponics over Semi Water Culture or Full Water Culture (FWC)?

Hydroponics is more indicated for orchids that prefer to have a short drying out period instead of a longer one. Their roots are constantly moist, in contact with water for the most part of their lives.

These orchids are most likely to be terrestrial, or live near streams, rivers, ponds and wetlands. These are the best candidates, but if you observe your orchid well, most all will transition to hydroponics without trouble.
Video: How to Transfer Orchids to Semi-Hydroponics

Are there orchids I shouldn’t plant in Semi-hydroponics?

Absolutely. When we think of orchids, we tend to forget that orchids grow in most every continent and there are desert orchids (which mimic succulents). Since in hydroponics the root system will be in contact with water all the time, these desert orchids detest hydroponics and will fail. Corallorhiza, Eulophia petersii, the steam orchid (Epipactis gigantea), Listera, and Platanthera will all fail in semi hydroponics.

If you’re interested in desert orchids, This article published by AOSOpens in a new tab. goes more into detail on how to grow orchids in drier climates, like Nevada.

Other orchids that are not suited for hydroponics are older orchids that are already established in the potting medium with bark, charcoal, sphagnum moss, and perlite. These older orchids will suffer more when trying to transfer them to another potting media.

Every orchid hates to be repotted, and an older orchids will have more trouble adapting to the new system. With a newer orchid, which is more flexible at adapting its conditions to new potting medium, the transition will be smoother and less viable to go wrong.

How does Semi hydroponics work?

Hydroponics is possible with a pebble-like clay ball, called LECA. Leca is Lightweight Expanded Clay Aggregate. This simply means that it is a clay ball that is heated to 2,190 °F (1,200 °C). The high temperatures cause the clay ball to pop, similar to popcorn. The heat creates thousand of micro pores, and a semi-hollow middle, yet the high temperatures also allow the exterior to become hard.

Some orchid growers have used seramis for semi hydroponics and from their results, it’s not recommended. I haven’t used seramis personally and don’t plan to, so I really can’t comment about it.

What others say is that the seramis beads don’t absorb as much water, leaving the top layer of the orchid dry and the bottom way too moist, causing major set backs in the root system. I’ve also read that the seramis mixture leaks out a lot of fine powder every time it’s watered, leaving a royal mess behind to clean. For beginner’s sake, keep to the LECA beads.

Back to leca… The thousands of micro-pores inside the leca are highly absorbent and by their structure, they pull and absorb water. This makes their absorption properties fantastic, which is what hydroponics is aiming for.

If there is a little water in the bottom of the reservoir, the leca pebbles will pull it to them. If another leca pebble is nearby, it also will absorb the water. This is how the medium will stay constantly wet and moist, but never have water soaking the roots, making them soggy.

Because of the thousands of pores, leca pebbles are extremely light. This can be positive or negative. If you have a large plant that tends to topple over or lean to the side, then leca pebbles will have a hard time securing this plant in the vase.

Cattleya orchid with grapes, cookies, and music

Because they are so porous, when you water, they will float to the top of your container.

Keep this in mind when watering, so you don’t “move” your orchid around in its pot.
When you purchase leca pebbles, aim for the bigger clay pebbles, as to the smaller ones.

The orchid’s root system will fill up the space in between the leca pebbles, and if they are too small, the roots may suffer from lack of air flow (even thought he pebbles are porous, the small pebbles don’t allow much air flow). Aim for pebbles around coarser material, 8 to 16 mm, or larger if you have a huge plant.

Even if you have a mini-Phalaenopsis, don’t worry about the pebbles being too big. The roots will adapt perfectly to the larger pebbles (which doesn’t happen in the traditional potting media with perlite, charcoal, and bark).

What’s the difference between semi-hydroponics and hydroponics?

Hydroponics is where you’d be watering daily. Since this method can allow you to go two weeks at a time without watering, this method of orchid care is technically called semi-hydroponics.

Transferring an orchid from sphagnum moss to semi-hydroponics in leca pebbles.

To transfer an orchid from organic potting medium to leca, you’ll need to take a few steps and carefully plan out its transition. Can it be done from one day to the next? Yes, but the roots are more likely to suffer. If you are transferring from sphagnum moss, take extra care to remove ALL the potting media. Any strand of sphagnum left behind on a root will decay and promote a fungal growth inside your leca beads.

Optional Products needed to transfer orchids in to semi hydroponics

Here is a list of totally optional products you’ll need, and can be added at discretion. All of these products aid the transition, but if you don’t have them, don’t fret about it.

Physan 20 – This is a “kill it all” product that is good to use when you’re not quite sure what your orchid has, but are quite sure something is on it. Fungus, bacteria, virus, mold… You name it, Physan 20 will kill it before it matures into something that is uncontrollable.

If you’ve already got a bad case, then Physan 20 probably won’t help, but if it’s just starting, spray it on the affected area and wait.

Usually after the purchase of new orchids or during a repot, Physan 20 is good to spray all over the roots, leaves and stem so any missed areas during the cleaning will be dealt with.

For transferring orchids in semi hydroponics, Physan 20 is good to use for spraying down the new vase you’ll use and the orchid before it sits permanently in the pebbles. This solution will need to be diluted in water when applied.

70% isopropyl alcohol – This is a good substitute for the Physan 20, if you can’t find it in your area. There is a stronger solution of 90%, but that will do more damage than good. You’ll also need to dilute this in water.

3% hydrogen peroxide – this is another solution that is used to get rid of any bacteria, larger critter like snails, and fungus that cause mold. It is less “toxic” to the skin than the 70% isopropyl alcohol, and still as effective.

The hydrogen peroxide will aid in allowing Hydrogen in to interact with the plant cells and aerate them, promoting cure in areas with initial rot to heal faster. If your orchid has any signs of root rot, crown rot, or and rot anywhere, don’t transfer it into semi hydroponics.

The rot got there because the medium was too moist, and they never had a drying out period. Cure the rot first, then maybe next year… In any case, you’ll have to cut the badly rotted roots off, keeping the healthy roots. If the rot is only on the roots, you can proceed to the transfer. If the rot in on the leaves, crown, or stem, keep it in the original potting medium (water the same, but allow more time to dry out).

Kelp Max is a seaweed based product that stimulates root growth. You can also use a fertilizer or other product that is specifically designed to promotes healthy roots growth, since this will be your main concern. As soon as new roots grow, you can successfully say you’re on your way to a home run.

 7 Steps to Transfer an Orchid into Semi Hydroponics

1) Cleaning the Leca

First, you’ll need to rinse the leca pebbles thoroughly in the sink. They come coated with a fine dust, which is only natural with all the pores that they have. But this initial rinse alone isn’t enough to cleanse them.

After the initial rinse, place the leca pebbles in a large pot and boil them for an hour. This isn’t an overkill because with that many places for bacteria to hide, you need to guarantee that they are very clean.

Once the pebbles have boiled, let them dry and cool off. If you plant your orchid in hot pebbles the roots will not withstand the temperature change.

Leca pebbles tend to be cool down, making the potting medium slightly cooler than the surrounding environment. When you chose orchids to transfer to hydroponics, choose a variety that are cool-growing compared to hotter climate orchids.

2)Choosing the right pot

Second, you’ll need to place the orchid in a pot with no holes or slits on the sides with a tiny layer of pebbles. Hold on… Don’t go overboard with the protests. This is the initial transition phase, where you’ll add a bit of water and drain it daily. In the final phase you will be adding more leca beads, and transferring into a pot with two or three holes, but not now.

3)Water the orchid in intermittent intervals to acclimate the roots.

Fill the vase with just enough pebbles to cover the rots and NO MORE. Fill with distilled water and keep the water in the roots system for two hours. Drain afterward. It’s even best if you take the orchid out of the pebbles, and lie it on the top of the glass container so the roots have constant air flow.

The next day, water again for two hours.



You need to do this for about a week, to acclimate the orchid in to the hydroponics. The original watering system was once a week (a little more or less depending on your environment.)

With hydroponics they’ll be in constant contact with water. Since the roots are not accustomed to this system, if you place them directly into hydroponics, they will rot and every single one of the roots will die. The orchid will (in time) grow new rots, but if you can avoid the loss of rots, it will benefit your orchid in the long run.

This is a good time to be using a root promoter, like Kelp Max or any other that you prefer. This will stimulate the roots, and that’s our aim.

Don’t even think about blossoms for the first year after you transfer the orchid. If you happen to get one, then count it as a blessing. But expect your results to not flower the first year.

4) Sitting in pebbles…and waiting patiently

After a week of watering daily for two hours and allowing to dry out, you can keep the orchid in the pebbles up to the top of the vase, but again, don’t keep a constant inch of watering the bottom. You’ll still want to water and dry out, but turning the vase to run off the excess water. There can’t be water in the bottom of the vase.

The leca pebbles at this stage will absorb the water, but still have dry parts, which will prevent the roots from totally drying out. Every day add to the time the orchid gets watered, until you see that the roots are doing well.

5) Fill the pot with pebbles and keep the lower portion in water at all times.

When your orchid is starting to produce new roots in this test phase of hydroponics, you can transition the pot to semi hydroponic, by filling it up with leca beads and always keeping a constant supply of water in the bottom of the vase. You’ll need to water about 2 to 3 weeks, just to fill the bottom layer until a little below the holes.

6) Don’t touch the pot.

Literally, don’t fret. Many orchid growers will plant their orchids in semi hydro and for the first three or four weeks, the orchid will decline. The leaves will turn yellow. The roots will die. The pseudobulb will wrinkle… and so on and so forth. Relax…. DO NOT TOUCH your orchid. You’ll be tempted to pull it out of the pot and repot it in something else.


Think of this semi hydroponic transfer as an adolescent who is learning to live up to their bad mistakes or choices. You can’t take away the consequences, even though it breaks your heart to watch them suffer.

If you try to ease the consequences and speed up the process, they won’t learn. They’ll become “crafty” and try to ease out of every future mistake.

But if they mess up and have to live up to their mistake, learning to repair the hurt they’ve caused,  they’ll be better off and stronger because of it.

Bad things happen… Just let them grow up. Same for the orchid.

If you take away the consequences of the new potting medium too early, the roots will suffer and become weaker in the long run. The roots will not have had time to adapt and will flop in semi hydroponics, then have a harder time transferring back in the original medium… And you’ll hate semi hydroponics.

Just like an adolescent let the orchid do its thing. It will adapt—both will.

(P.S.: I hope it doesn’t come across too badly in my writing that I’m currently raising two adolescents. Anyway… )

7) Repot

So, you’ve given your orchid at least six months to a year to adjust to semi hydroponics.

Not all orchids will adapt. Some do, others don’t.

Don’t blame yourself it the experiment didn’t go as planned, but only after six full months have been completed. If by then, no new roots have grown, the leaves have all fallen off, your poor orchid is on its last leg, then and only then, repot it back into the original media it was in.

Not everyone is made to live overseas in different cultures, and some people just get extremely homesick… Same with orchids. They just get home sick for their old media.

How to water your newly transferred orchid

In the semi hydroponic method, you don’t need to water as much as if in a pot with bark, sphagnum moss, and charcoal. Every two weeks, or when you see the water level lowering more than your holes, take you orchid to the sink. Run room temperature water over the orchids until the water fills the brim of the vase, and flows out the bottom holes.

Remember that LECA is lightweight? Well, if you water above the rim, the leca will float to the top and run out of your vase. So keep the watering just to the brim.

If you notice that around the holes of the vase or in the vase there are white, sandy powder which has accumulated, then either the eater you are using is too mineral saturated, or the leca beads weren’t boiled properly. It can also be because you’re fertilizing too much, but it’s probably the water.

If this happens, rinse the entire pot several times by filling it and letting it pour out. This is called flushing a medium. It’s almost the same as watering, but you’ll do it repeated times to remove all the debris. With this guide, you can transfer your orchid from any potting medium into semi hydroponics. Start with one orchid, see how it goes, and slowly transfer your orchid collection once you’ve had success with one.

If there is anything that was unclear or wasn’t covered in this guide, drop me a comment in the box below.

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Happy Cultivating!

Signature Amanda Matthews

Amanda Matthews

Amanda Matthews is a theological professor, author, pastor, and a motivational speaker. She's passionate about spreading hope and teaching. Her hobbies include biking, cultivating orchids, and exploring nature trails. She now lives in Kansas, while raising her two children. To read more, go to

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