The Down Side to Semi Hydro (S/H) and Full Water Culture (FWC) for Orchid Care Thinking about jumping on the bandwagon? You might want to reconsider...

In Orchid Tips & Care
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I want all orchids to thrive and I believe other orchid growers should experience the same joy and success from growing these plants, that I do. After helping countless other orchid growers with their plants and seeing so many people struggle with and kill orchids with semihydro and full water culture, I want to expose “the other side” to these “always wet” growing methods. If you’ve had success with this method, fantastic—this isn’t an attack on you or your ability as an orchid hobbyist, but just beware that not everyone comes from the same climate and conditions as your own and further, always wet growing methods may not be universally effective for all growers or all types of plants. If you’re currently growing always wet and your plants are struggling and/or you’re considering this method for yourself, this article should help you understand what challenges you may face.

If you’re not interested in finding out what I don’t recommend and you’d rather get some insights on how I successfully grow orchids currently, you might want to refer to how I grow 300 orchids in my condo (up in dry/cool Alberta, Canada); and if you’d like more information on caring for phalaenopsis, refer to this guide to phalaenopsis orchid care.

What are “Always Wet” Culture Methods?

Semi-Hydro (S/H) or Full-Water Culture (FWC)—what I call, “ALWAYS WET” culture methods—are two ways of growing orchids that are notoriously branded as “the easy way.” In these two growing methods, the roots of the orchid continuously sit in a stagnant pool of water. The intention is to provide the roots and plant with a constant supply of water at all times. You see it’s “always wet“—because the roots are…always wet!

Three problems with always wet orchid culture are: 

  1. Unsuspecting (and new) growers may experience a high failure rate because they assume it’s a care-free method. The assumption is that the orchid has access to an always available reservoir of water meaning the grower can relax about watering frequency. Unfortunately, the method skips over important scientific details like how water pH affects nutrient availability, and how climate (temperature, humidity, evaporation rate) affect the root environment. These aren’t beginner concepts and s/h and fwc may give a false sense of understanding, preventing a grower from effectively troubleshooting problems.
  2. Phalaenopsis growers specifically often run into problems with roots because the cool temps (down to 16•C) that “common phals” need to initiate flower spikes, in combination with wetness, are a perfect storm for fungal and bacterial infection. Cool + wet == not good for orchid roots! But orchids still need to be watered even if the temps are lower. Conversely, summer-blooming phals (which require evenly-moist roots and warm conditions) often struggle if a grower’s climate is dry because the top layer of the pot or vase is simply too dry while the lower section is wet.
    • Fun Orchid Care Fact Many growers will use organic media (such as bark and sphagnum moss) because those materials absorb, hold, and distribute water and humidity more uniformly across the inside of the pot and therefor across the entire root zone; this trait of organic media can help a grower better mitigate a dry or cool climate. Saturated Sphagnum moss alone holds over 18x it’s weight in water (and 4x the volume of water that LECA holds); bark can hold over 35% its weight in water (and 2x the volume of water LECA holds); but LECA only holds 19% of its weight in water when saturated and because it holds the least amount of water compared to all of the mentioned orchid medias, it also dries out the fastest. In a dry climate, the main problem with always wet growing methods, is the top of the pot (and base of the plant where new roots emerge) becomes harshly dry while the lower half is soaking wet—many orchids are not well adapted to these conditions. It requires that the plant be able to succeed within two different climates within one root – and while some orchids are adapted to harsher “rock habitat” conditions like this, many just aren’t. The result is often that new roots often look shriveled and abort before ever reaching the water and old roots are at high risk of rotting. Having fewer roots potentially sets the orchid back for that growing season; and after many months the plant can slowly decline losing leaves and roots gradually until the grower tosses out a ratty and sad-looking plant.
    • Did You Know: the inventor of the semihydroponic orchid method, doesn’t grow his phals in semihydro? It’s true. His phals are potted in sphagnum moss.
  3. Using strictly inorganic media doesn’t allow the grower to custom-tailor the drying rate of the potting mix to the needs of the orchid and their climate. Experienced growers understand that using a blended potting mix of organic and inorganic materials, gives them the ability to regulate the dry-out rate of the potting mix and subsequently the roots. By altering the ratio of organic additives like sphagnum moss and bark to the ratio of structure-providing inert materials like perlite, pumice, and leca you can make a potting mix that dries within days or make a potting mix that stay moist for a full week.

 

If you’re a phalaenopsis grower, I encourage you to check out this post.
It’s loaded with good information & care tips for more flowers.

 

Coming From a Place of Experience:
I Used to be a Dedicated Semi-Hydro Orchid Grower!

For the first two years of my orchid hobby, I grew in exclusively LECA as a semihydro grower and I continued using semihydro for about 4 years in total. At the time, I lacked the experience to understand the relationship of temperature, climate, humidity and rock-like substrates, and because my plants flowered, I thought I rocked at orchids. However, I’ve since realized that the act of flowering does not equate “thriving” or even survival. An orchid will sometimes flower as a last-ditch effort to save its genetic lineage and in specific cases, flowering may indicate that the plant is stressed, not thriving. There were a lot of genera I killed in S/H very quickly; while others like phals languished, only ever having 3 or 4 leaves at any given time. Compared to my plants now…that was not “orchid success.” In the end, the majority of those plants eventually died and I considered myself a “bad grower.”
Plants plants plants plants...ORCHIDS, ORCHIDS!! Thank god it's nearly spring! #plants #orchids #growAreas

I stopped buying plants for a few years and spent some time observing successful growers (those who grew in s/h, water culture, and organic), I ask questions, and I began to see trends based on where people lived, the types of plants they grew, and their perceived success vs. actual success with their chosen growing method. Consistently the good growers in indoor dry or cool climates used some amount of organic media.

Good Bye S/H, Hello actively watering plants every week

I stopped using semihydro and opted for a more traditional semi-organic orchid potting mix; and I changed how i watered my plants so that I could start using tap water. Now I DRENCH my plants once a week—literally shower them leaves and all. It was shocking how much better the plants grew with just a few tweaks to care. My phals stopped dropping leaves, orchids stopped dying, and the plants in my collection started to mature and become specimen-sized orchids. I didn’t even know that this was possible, but did you know a single phalaenopsis leaf can last for 3-5 years?! My oldest phals typically hold anywhere from 10-23 leaves and they grow an average of 2-4 leaves per year—it’s not uncommon that my phals will produce 2 leaves AT THE SAME TIME! And of course, because there are more leaves when it comes to blooming, the plants produce more flowers. The roots on my plants are also more prolific, they don’t abort, and because they have more roots and can take up more water and nutrients at each watering – resulting in faster growth. Understanding how organic media works to create a “micro climate” around the roots (which is both more consistent and forgiving in my dry climate) transformed my love of orchids. I stopped killing plants and starting GROWING them for years on end.

As I became more confident in my ability to grow orchids, I deflasked orchid seedlings in 2017. The following year (2018), I started breeding and raising my own orchids from seed! And a tip: if you want to find out what growing method, or light, or potting media, or fertilizer works best, then buy a flask of orchid seedlings and test groups of the seedlings in the different conditions—put orchid seedlings in semihydro or water culture. You’ll find out very quickly what works and what doesn’t and if you can’t get a seedling orchid to grow in semi-hydro or water culture…do you really think it’s ideal for the adult version of the plant?

My two largest non-semihydro / non-water culture phals – ~3 years old

Photos of my current orchid collection – NOT in semihydro

“Always Wet” is bad for Orchids and GREAT for bacteria and fungal growth in the root-zone.

WHAT??! you ask? Yeah, wet is where bacteria and fungus like to grow and it’s how spores germinate and pathogens spread. Constantly wet environments are not where most orchids have adapted to grow (excluding some Phragmipediums of course) and so they may become more susceptible to infection depending on the species you’re growing. The vast majority of orchids grow in habitats that experience distinct, quick, and repeating, wet/dry cycles—you know, in a rainforest. That’s why orchid roots have evolved to suck water up quickly and store it for periods of drought. This is why some orchids do poorly in always wet growth methods, while others are better able to survive…the problem is, the growers who advocate for this method, rarely show photos of their sad, dying or dead plants.

If you’ve seen some types of phals grown in always wet methods, you might notice their roots reach out and up away from the leca or water? That should tell you something. It should tell you that the orchid is reaching for conditions that are better — and I know that sounds a bit silly…but this is how I know if the potting mix I’m using is old or not good; when the phal roots start reaching out of the pot and splaying away from the media…it’s either time to repot or maybe choose a new culture method.

A side story: When I was growing in S/H, I ended up losing nearly 35% of my collection to what I assume is a fungal or bacterial infection (but very well could have been a virus). Below are a few photos of what I was dealing with. I believe it happened because I was reusing water (not much mind you) but I reused a bit and the pathogen spread across a third of my collection, killing all that it infected.

Phalaenopis gigantea - new leaf
Phalaenopis no name
Phalaenopis stuariana - old leaf

Shame on me for reusing water, right?

Well, that was also a symptom of a bigger issue…I was buying ~4 x 10L jugs of distilled water every month. I would add special MSU orchid fertilizer for distilled water, but buying 40L of water at $10/bottle added up pretty quickly. It was expensive and I tried to cut corners by preserving water. As I filled one pot, I would let the excess water drain from one pot to the next. I never transferred the same water to all of the pots. I literally just used the next pot to catch the excess water from the pot I was currently topping up. So the pathogen spread rather easily considering I wasn’t dunking the pots in a vat of water. Still…shame on me, right?

Probably…but let my failure be a lesson for you. I still have more reasons why I really don’t like always-wet orchid culture.

Why “Always Wet” is bad (the WORST) for Orchids:

  • Fungus + Bacteria: Yup, beating this dead horse again (it’s like a bad ex and I definitely have baggage from this one). Baseline concept you need to know: it’s easier to get bacterial & fungal infections in your orchids because you’re creating the perfect conditions (wetness) where those pathogens thrive and spread.
  • The “adjustment period”: new orchids have to “get used to” these always wet conditions—some can take up to 6 months (or more) to get the “right roots”. Those that don’t adjust generally just die…but the ones that do adjust are generally set back a bit. It was a shocker to me, but that adjustment period isn’t normal. I literally don’t experience this anymore…and if I don’t see new growth within the first few weeks of getting an orchid, I know something is wrong. 99% of the time, I repot new orchids and they keep growing like nothing happened.
  • Old Root Die Off: Older roots die because they go from the old dry conditions to new wet conditions that encourage bacterial growth. Old roots often get rot and fall off which also means there’s a lag from when you repot the orchid into FWC/SH and it’s subsequent establishment in the new always wet conditions.
  • Less Roots: It seems that orchids grown in water culture tend to end up with less roots overall—likely because the wet/dry cycles that stimulate new root growth…are absent. A lower root count on unestablished plants can easily yield higher rates of death.
  • Roots Reach and Actively Grow Away From the Water: They don’t want to die so they’re trying to find better conditions.
  • New Roots Abort: Growers will often experience aborted roots because the material (terracotta – Leca/Seramis) actually starts pulling water from the plant when it gets too dry! That’s a big problem if you live in a dryish climate (under 70%). 
  • Shriveled leaves and pseudobulbs: This happens from dehydration—simply put, when you stop actively watering your plant, it becomes dehydrated. I actually didn’t know this…but Oncidiums ARE NOT SUPPOSED TO HAVE SHRIVELED PSEUDOBULBS! (Same goes for Miltoniopsis—not supposed to have shriveled pseudobulbs).
  • Too Dry at the Top: Too much air flow (large pebbles) which dries out the roots too quickly, or rather it dries out the top layer of the medium while the bottom layer is still wet (terrible conditions for new roots). The water-wicking affect of the leca/seramis only works effectively if you’re in a humid climate and the water has a chance to wick all the way to the top.
  • Too Wet and Stagnant Around the Roots: Too little air flow (small/variable sized pebbles), can prevent air flow to the deeper root zone (not the end of the world, but air circulation through fans or something should be used to force air through the medium…or you really risk rotting your orchid roots).
  • Increase your pH? I have seen videos on youtube that verify that intert substrates can increase the pH of water substantially (into the range of 8.5-9.0)…I’ve also seen videos of people countering this. So the jury is out–admittedly, I don’t really care too much about pH. A story for another post.

But everyone online says Full Water Culture and Semi Hydro are THE BEST…

Yeah, trust me, I’ve heard all the claims too. Here’s the problem, if someone is saying how great FWC or SH is…ask them to share photos of their orchids in in SH or FWC. 90% of the time orchids growing like this look a little rough. If you find a grower who is succeeding with either method, ask them about their climate and growing conditions and dig beyond the potting method. Ask about their temperatures (max and min), ask about their humidity, about their water pH, about which fertilizers they’re using and how much light they’re providing. See if their conditions match your own and if they do, then maybe you’re in luck and always with methods will work in your favor.

Compare for yourself:
Photos of my phals NOT grown always wet
each with 7 or more leaves

In general an orchid that is growing well and is happy should have firm leaves, good leaf growth (if it’s a phal, more than 3 leaves), numerous flowers (if in bloom) and a lot of roots. Look for that in the images of the orchids people show you. This is never a pissing contest—it’s a proof contest. Get your proof and see that the growing method actually yields success, because you’ll find often times it does not.

FWC phals ALWAYS look like they’re on the edge of death…2-3 leaves that are often floppy, 2-4 roots with literally no root growth visible in the water (but often roots growing away from the water), and if the plant is in bloom, it has anywhere from 2-4 flowers (5 if you’re lucky)–NOID phals should generally hold about 7-14 flowers without having to manipulate any major temperature adjustments.

SH orchid sometimes look fantastic…but often times they really don’t—black leaf tips, black spots, bacterial infections (yellow spots or chlorosis) or burnt roots.

I have occasionally been proven wrong…only a handful of times, but in those cases the grower generally lived in humid climate, they grew their plants in a greenhouse, or the plant they have is one that comes from a drier climate where it had adapted to seasonal variations and therefor was better able to mitigate both wet and dry conditions.

Okay, I’m Done With My Story & Experience. Choose what works best for you

If you’re having good success with either of the two always wet culture methods, then that is fantastic! This is my experience, observation, and fragments of knowledge that I have now shared with you. If you’re curious if it will work—TRY IT! Don’t be scared of growing orchids and experiment to see what works for you, your lifestyle, your climate and your orchids.

If you’re still planning on growing your orchids “always wet” – Watch this video first


 

Happy Orchid Growing!

“But Dustin, you said proof is in the pudding…where’s your proof?!”