Cultivating Orchids & Crafting Terrariums

Pros and Cons of Semi Hydroponics
in Leca Pebbles for Orchids

If you’re thinking about transferring your orchids from the traditional potting media, (orchid bark, perlite, charcoal, and sphagnum moss) into a semi hydroponic media with leca pebbles, then you’ll need to consider a few things first. The semi hydroponics has pros and cons, and in this article, you’ll learn what to expect.

The pros of transferring your orchids into semi hydroponic media are: (1) less repotting, (2) better view of the roots, (3) less stem and root rot, (4) less pH variances, (5) easier to treat pests, and (6) less financial strain over time. The cons of semi hydroponics for orchids are: (1) higher initial cost, (2) hard for larger plants, and (3) harder to supply quality water. Let’s look at those one at a time.

The Pros of Semi Hydroponics for Orchids

1) Less Repoting

Orchids detest to be repotted, and more sensitive orchids are more prone to not blooming the year that they’re repotted. If you think about how they grow in nature, under the open canopy of the forest leaves, firmly attached to the nooks and crannies of trees, you’ll see why they aren’t found of being messed with. The velamen (the fine protective covering of the roots) has filaments that attach themselves to their surroundings—in nature’s case, the tree bark.

When they attach themselves to the tree, they don't plan on moving. That is why the roots will cling to the exterior of whatever it can hold on to. This is how the orchid survives in nature, and won't fall off after a strong rain or storm.
Semi Hydroponics for orchids
"Cymbidium Sue 'Autumn Sunset'" by dorofofoto is licensed under CC BY 2.0  
This also happens inside your orchid pot. The velamen on the roots attaches itself to the orchid bark, charcoal, and the sides of the pot.

When you repot them, you always risk tearing away some of that velamen, harming the absorption qualities of the roots.
With semi-hydroponics, you won’t ever have to take the orchid out of the leca pebbles until they outgrow their pot. The good news is that you can repot them in a pot much bigger than the one or two inches recommended with the traditional potting media.

A tiny plant won’t have the need to attach itself to the outside of the pot as much as it would in a traditional bark. So, you can use bigger 12-inch pots and let them grow for years on end.

This in itself is also a financial gain.

Every time you repot you need to use materials that are costly, when added up. Leca pebbles are reusable, if you boil them and let them soak for a few days before applying them to a second plant, so even if you have an orchid give up on life, you can reuse the media.

Less repotting saves you time, money, and root quality.

2) Better view of the roots.

In semi hydroponics, the orchid will sit in a clear plastic or glass vase (with several holes in the upper 1/3 of bottom side, so they can retain water but still drain at a certain height). The clear vase makes it possible to see the amount of water in the vase at all times, so there is no guess work at the correct watering period.

If you are a beginner, then watering with semi hydroponics is definitely the best and easiest way to start (That is...once you have all the correct information. One grower thought that semi hydroponics meant the orchid always sat in water up to the brim and the orchid lead a slow suffocating death.) If you have the correct information, then orchid growing with semi hydroponics is definitely easier.

But watering isn’t the best part of semi hydroponics.

With the clear vase, you can see the roots and how healthy they are. You can verify how many of them are growing and expanding through the media.

In the traditional potting medium, you have no idea how the roots are until you repot. This can bring some unpleasant surprises. The orchid might have beautiful leaves and produced a full, vibrant blossom, only to find out later when you repotted, that the roots had all decayed. This can happen because the blossom might have been a last saving grace as the way the orchid had to cry out for help.

3) Less Stem and Root Rot

When the traditional potting media is over watered, both by watering too frequently and by offering a higher quantity than the orchid needs, the orchid can’t dry out. Having the roots sit in constant humidity promotes root rot.

This happens not because of the water directly, but because the roots can’t breathe in the water logged medium. Without proper gas exchange, the toxins build up in the velamen, killing the root.

With dead decaying material in contact with water, fungus, bacteria, and mold build up around the roots. If not treated, this rot will spread up the roots and into the stem. Once installed in the stem and particularly in the crown, the orchid is off to its death.

With semi-hydroponics, the leca pebbles allow for air circulation as well as an abundant water supply in a balanced proportion. Leca is known for absorbing water, but it also absorbs air. Its high porosity allows for multiple air pockets, allowing the roots to have contact with the air, without being either overly wet or dry.

4) Less pH variances inside the potting media

The downside to potting with traditional potting media, is that it will break down over the months, and after two or three years, you’ll need to repot.

The main reason isn’t that the media is compacted (although this does highly influence the health of the roots) but that the pH is going to adjust with the decaying material in the pot.
Pros of Semi Hydroponics for Orchids
"File:Orquídea (Cymbidium iridioides) (14228982208).jpg" by Alejandro Bayer Tamayo
from Armenia, Colombia is licensed under CC BY-SA 2.0
Most orchids (expect the terrestrial ones like paphiopedilums) like a more acidic medium, of around 5.5 to 6.5 in pH. (Just a reminder that a neutral pH is 7, and most hardwater or tap water is around 7.5). Sphagnum moss does a great job at keeping the pH down, more towards the acidic side of 4.5—in the beginning.

Only later does the sphagnum decompose and the pH does bizarre things in your potting media. The fluctuating pH invites fungus and viral infections, since the orchid is struggling to maintain alive in the extremely toxic environment.

Leca pebbles are neutral in pH and will always remain neutral. There are no fluctuations in the environment, unless the water you use is highly acidic or alkaline. If you do not add any outside variables to the potting media, then your leca pebbles will always remain the exact pH that you intend it to be.

Note: it’s important to do some research on specific orchid types so that you’ll know what’s the best pH for your orchid. Each orchid has its own preferences, and this can be different for specific species inside the same genera.

So please research.

5) easier to treat disease and pests

When you have a pest inside your potting medium, the treatment with neem oil, diatomaceous earth, and other insecticides, pesticides and fungal removal products becomes a hard task. With semi hydroponics, you can easily see if your media has pests.

Second, most pests stay away from the semi hydroponics media because it doesn’t provide the conditions to lay eggs and larvae like orchid bark and charcoal do.

Pests will be easier to see, remedy, and keep away for good.

6) Less Financial Strain Over Time

The initial cost of the leca beads can be quite high. There are poor quality leca beads on the market, and these are quite cheap. But they don't absorb or circulate the water inside the potting media well, and the top portion of your orchid will be constantly dry.

Yet, once you’ve set up your orchids hydroponically, you’re home free for a couple years. No more potting media, charcoal, orchid bark, perlite, and other costly material.

Leca beads are also reusable, as mentioned before.

If by any chance your poor orchid bites the dust, you can boil the pebbles, and reuse them for another orchid. This could never happen with traditional potting media.

The Cons of Semi Hydroponics

1) The Initial Costs is quite high and comes with a learning curve

Investing in orchid pots is something I would have never imagined to be costly. Yet, for some unknown reason to me, orchid pots are expensive. And glass vases even more. If you’ve ever tried to drill holes in the glass vases, you know that some will eventually crack or chip. If you use better quality glass, this won’t happen, but it also raises your initial expense.

The leca pebbles are costly, too. Even though they are reusable, they are not cheap to set up. And let’s face it, a lot of pebbles are necessary to fill up a big vase for a larger plant. The initial investment is quite high, but as mentioned in the last point, it does pan out over time.

The learning curve is a bit higher too. You can’t just peel off the sphagnum moss or whatever the initial potting media was, and plop your orchid in leca. There is a little bit of a learning curve (not as much as full water culture) but you’ll still need to read up on the proper care for the system.

2) larger Plants topple over

Leca pebbles are incredibly light weight. When watered, they float to the top of the media. This makes them a good variable to keep in the vase, but if you have a larger plant, usually an older plant, it will topple over to the side.

Orchids grow of towards the side when in nature, so that rain droplets won’t settle inside the crown of the orchid. They naturally tend to droop over to the side.
Cons of Smei Hydroponics
"File:Cymbidium . - Flickr - gailhampshire.jpg" by gailhampshire from Cradley, Malvern, U.K is licensed under CC BY 2.0  
If you have a thin glass vase, then this isn’t the best solution, because the orchid will make your vase turn over.


You’ll need to keep a counterweight on the plant to secure it in place.

3) Better Water Quality is Hard to Find

Since you are trading all the traditional medium for leca pebbles and water, your water will need to be of an excellent quality.  I mention the differences between tap water, soft water, distilled water, and reverse osmosis water in this article and what’s best for your orchid.

Depending where you live, you can have an enormous quantity of added chemicals to treat the water. This will harm your orchid more than you can ever imagine. Soft water also adds to the salt retention and build-up on the top layer of your potting medium. You’ll need to use the best quality water that you can, to maintain healthy orchids.

A final consideration about semi hydroponics

When you think about transferring your orchids to semi hydroponics, don’t just analyze a list of pros and cons. There are so many other variants that you need to analyze before even starting.

First, what’s your routine like? Many people find it therapeutic to take care of plants and spend lots of time with them. In semi hydroponics, you’ll be in less direct contact, as in repotting and watering, than you would with traditional potting media.

Can you take your plants to the sink or tub and water them weekly, or do you prefer a misting method? Make sure you chose orchids and watering routines that fit into your schedule, so orchid care will be a pleasure, not a chore.

Second, are you willing to invest in learning about proper water care and pH? This isn’t absolutely crucial, but I would have never started semi hydroponics without knowing exactly what I was doing. There is a learning curve, as mentioned before, and it does take trial and error.

Which brings me to my last point, are you willing to sacrifice a few plants in learn? When you transfer your orchid to semi hydroponics, it will suffer. It will take a direct hit, and possibly lose the majority of its roots. Until it grows new roots, your orchid has a great chance to dying.

This is a high risk, especially with a more expensive orchid or one that is dear to you for an emotional reason. Always start semi hydroponics with the orchids that you don’t mind losing until you have mastered the learning curve.
I hope that this information helped you. If there was anything pro or con that I forgot to mention, please comment below. The more we interact, the more we all learn.

Happy Cultivating!
Signature Amanda Matthews
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ABOUT ME 
Amanda June Matthews at Orchideria
Hi, there! I'm Amanda Matthews.

I write all the tutorials on Orchideria so unfortunately, I can't blame anyone else for all the spelling mistakes.   :)

By profession, I'm a theologian, author, and seminary professor, yet I  spend my free time enjoying nature hikes, building terrariums, and cultivating orchids. I also love to mountain bike on trails, dance, and play with my dog, Max.

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