The Down Side to Semi Hydro (S/H) and Full Water Culture (FWC) for Orchid Care Some considerations based on personal experience

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 many orchid growers with their plants and seeing so many people struggle with and kill orchids in semihydro or full water culture, I want to offer a different perspective to these “always wet” growing methods. In some cases it seems semihydro and water culture methods are overhyped and the negative issues are rarely addressed, and that’s what this post is—covering the challenges I faced and explaining why some of those things were issues for me.

If you’ve had success with these water-based methods, fantastic—this isn’t an attack on you or your ability as an orchid or plant hobbyist. Just beware, that not everyone has the same climate, water quality, or conditions as your own and further, always wet growing methods may not be universally effective for all growers or all types of plants. I also recognize that this means not everyone has my conditions either and my experience is not universal. If you’re currently growing your plants in s/h or water culture and they’re struggling, or you’re considering this method and want more than just “the sunny-day scenario”, this article should offer clarity to some of the potential challenges you may face.

Before I get into the downside: I was serious when I said, “I want all orchids to thrive”, so if you are actively researching semihydro with the intent of transferring your plants into LECA, check out @the.orchid.room. Annabel is from the UK, and she grows exclusively in semihydro. Her plants are some of the largest and most impressive examples of home-grown orchids I’ve seen—to me, you can’t argue with that, and clearly ‘always wet’ methods can be utilized if you spend the time to understand the details and test different variables for yourself. I have always recommended that new growers invest their time learning from growers that have glorious collections that can back-up what advice they have to share. Prior to knowing Annabel, I had observed many semihydro growers having inconsistent results and I didn’t see them diving into those details to show if something was actually working. Some channels were great examples of why semihydro doesn’t work—but to new growers, the plants looked alive which was good enough. What I appreciate most about @the.orchid.room (beyond her well-grown and beautiful collection), is her transparency about her process, along with her evidence-based approach to testing the many different variables, AND her willingness to challenge “common rules”—including those that exist within the “semihydro rulebook”. For example, Annable started using stones (instead of LECA) on the top layer, which helps move the moisture zone higher in a pot preventing rapid dryout at the base of the plant, that is a super-valuable adjustment for people growing in dry climates. It’s simple but smart and I find her channel offers a lot of those types of fine details. So if semihydro is your pursuit and you’ve heard the warnings I’m about to cover below, please do yourself a favour and go follow her channel.

If you have seen my YouTube channel or Instagram and want to know about my growing methods, I’ve written a detailed but introductory post on 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. I cover other orchids like paphiopedilums and phragmipediums on this site too, so browse around and absorb any information you find valuable.

 

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 and plants that are notoriously branded as “the easy way.” In these two growing methods, the roots of the plant 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 possible problems with always wet orchid & plant 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 always has access to a reservoir of water, meaning the grower can relax and not stress 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) may affect the root environment. Root conditions and pH aren’t beginner concepts and it may give a false sense “good enough”, preventing a grower from effectively troubleshooting problems. That channel I mentioned above (@the.orchid.room) she talks about pH adjustment and can help you understand how to do this should you want to get into these details.
  2. Phalaenopsis growers specifically often run into problems with roots because the cool temperatures (don’t go lower than 16•C) which can help “common phals” 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 may not be well adapted to these extreme 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 because he had better success using moss in a cooler more northern climate. If s/h didn’t work for his phals in central USA, how could that be a great choice for people growing phals even further North? Unfortunately, prior to the publication of this article, that information wasn’t disclosed in any of his semihydro ‘how to’ pages.
  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. As growers becomes more experienced, they learn that adjusting the ratios 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, a grower can make a potting mix that either dries within days or stays moist for a full week. That understanding can be helpful if you’re growing a plant like phal wilsonii that responds to wet dry cycles, or for a plant like phrag kovachii that needs moisture right up to the base of the plant at all times.

 

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 exclusively used LECA as a semihydro grower. 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 was succeeding at growing them. However, I’ve since learned 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

After this, 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. I noticed that a lot of the best indoor growers 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 instead of distilled ‘pure’ water. Now I DRENCH my plants once a week—I 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. With more leaves, came 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.

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, wetness is how bacteria and pathogenic fungus spread. Constantly wet environments are not where most orchids have adapted to grow (excluding some Phragmipediums of course) and so epiphytic plants adapted to wet/dry cycles, 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 can do poorly in always wet growth methods, while others are better able to survive.

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 is a sign 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 means it’s too wet.

A side story: When I was growing in S/H, I ended up losing nearly 35% of my collection to what I believe was a fungal infection of Fusarium solani (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 easily. But that was my fault – shame on me for cutting corners.

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

  • Fungus + Bacteria: Yup, beating this dead horse again. 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. If you’re re-using water or pots or LECA from plants that die, and you’re not sterilizing those things, you’ll easily transfer that to more plants. Don’t share or reuse LECA or water unless you heat them to 121C for 10 minutes or more to sterilize them.
  • 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.
  • 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 or minerals start to buildup if you’re not flushing frequently enough. That’s a bigger 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. Newer semihydro growers have started to mitigate this by adding sphagnum or stones to the top layer – the sphagnum can help, but will start to degrade over time and will make cleaning your LECA a problem for repotting.
  • 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). Same goes for those who don’t actively water regularly—a film can develop on the surface and block airflow into the water which can choke roots. This could mean you have “good good good”, then a crash of roots if you’re not diligent about keeping the reservoir turned over often.
  • Increase your pH? There are reports that some LECA brands increase the pH of water substantially (into the range of 8.5-9.0). I’ve also seen videos of people countering this. So just be sure to check your pH and if you’re using new LECA soak/leach it before using it b/c a pH over 8 will lead to nutrient lockout and a plant will decline slowly overtime without access to nutrients like iron and nitrogen.

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

Welcome to Facebook groups, where anyone can say anything without any proof to back up their perspective. If someone is saying FWC or SH is a great option…ask them to share photos of their orchids in in SH or FWC so you can see for yourself how their plants look. Too often, I’ve seen growers tout the amazing power of always wet methods, but when they show their plants…they 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. Seek to understand the methods as they understand it, because it’s not as simple as putting a plant in water and topping it up once every 3 weeks.

Photos of my phals in organic media
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.

That covers my experience. Choose what works best for you

If you’re having good success with either of the two always wet culture methods, then 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?!”