👋🏻 Heyo from my Canadian jungle apartment

[here_butnot]

Originally Posted by YetAnotherOrchidNut

Hi Dustin, just wanted to say you majorly influenced my thinking on plants. Your posts really crystallized my understanding of my experience with growing orchids and other plants at home in my living room. Thanks a lot. I regularly check out your site. I am glad to find you here, I try to avoid facebook and I always wanted to ask you a question. :-)

Hey YetAnotherOrchidNut, thanks very much! I'm glad you've found the blog helpful and I'm thrilled you feel it's helped you become a better grower. I think sometimes it's just pivoting a few core ideas that can really unlock our understanding of plant care and I'm glad I've helped transfer some of my ideas there to you.

Originally Posted by YetAnotherOrchidNut

The question is about your potting media choices. I have never noticed you mentioning vermiculite in your writings, which I find odd. It has about double or more the water retention of perlite and dries a bit slower, but much lower water retention than that of peat, and correspondingly much higher oxygenation than peat as well. So it seems like it would be a good option for plants like Macodes and Ludisia that need high moisture but also high aeration at their roots.

I recently was motivated by your posts on the Macodes to buy three different Macodes seedlings (petola, petola gold, and sanderiana) and instead of using your mud-mix (50% peat/50% perlite) and frightened by the high sphag option - I altered the mud-mix by cutting the peatmoss in half and replacing it with vermiculite. I fear the cold, dark, damp part of the year here in Amsterdam is too damp for that much peat so after some experimentation with alternates I picked vermiculite as a substitute. Too early to tell if that was a horrible mistake but my Ludisia is in a similar mix and it seems happy.

Is there a specific reason you don't use vermiculite for your plants? Or is it just because? Given how common a soil amendment it is it always struck me as an odd omission from someone as thorough and scientific as you are.

Thanks again for the great articles on your blog, its been a great motivator and education. I really think you made me a much better grower, and a much braver grower. "high humidity" requirements no longer scare me. :-)

Regarding vermiculite, I've just never really gotten into using it. I find that it's quite small and particulate and with most of my plants, my approach is to utilize chunky airy media that allows for lots of airflow and drainage between the particles. It's also just not that readily available here.

That said, I'm interested to see how your experiment turns out. I think it sounds like a pretty solid option. I tend to view media as water retention vs. drainage and airflow. Peat, sphag, coco coir, and vermiculite all fill that same role as water retention, so as long as your media isn't too wet for too long, it should be just as good (if not better???).

Keep us posted.

[Shadeflower]

I don't think I've seen anyone use vermiculite to grow orchids.

I think it isn't airy enough. The main aim should always be to have an airy and humid substrate. Never just humid.

Roberta recently shared she does use soil to grow rupiculous laelia's so I'm sure it can be used if there is enough ventilation throughout the pot.

If it helps, this is just my personal opinion but I have in my head compiled a list of organic media and their closest organic counterpart that acts in the most similar way.

So:
bark <=> pumice
spagnum moss <=> small grade perlite
vermiculite <=> soil

lecca is very similar to pumice but has got some noticeable differences. Growing in bark alone is fine, growing in pumice alone is fine but lecca is a bit different in that it needs to be used in S/H to keep it moist or in combination with another media. By itself if it is let to dry which it does very fast it desiccates roots more than the other substrates so lecca is a bit of a case of its own that doesn't have any organic counterpart that acts the same I find.

Hope it helps, it is by no means a scientific comparrison and in a hotter climate these substrates might all act differently to my rough observations. No substrate is ever exactly the same.

[Mountaineer370]

I'm late to the party but just wanted to say welcome to the Orchid Board, Dustin! I had discovered your website/blog a couple years ago and have enjoyed the articles there. I only realized recently that you have a YouTube channel, so I will definitely check out some of your videos.

[camille1585]

Me too, I've very late to the party but was on vacation when this thread was created, and completely missed it.

Welcome to Orchidboard Dustin!!

I too enjoy reading your blog, and am quite envious of your amazing looking Phals! I 'specialize' in Phals, but they are very far from being as gorgeous as yours.

[YetAnotherOrchidNut]

Originally Posted by Shadeflower

So:
bark <=> pumice
spagnum moss <=> small grade perlite
vermiculite <=> soil

lecca is very similar to pumice but has got some noticeable differences.

Slightly out of order, Leca is widely sold at inexpensive prices in Amsterdam at hardware stores and the like, usually in 10kg and 20kg bags. It is far easier to get leca than pumice or gravel. So I routinely mix in washed leca with my bark, and i routinely use a leca drainage layer in the bottom of my pots. My phals *with* leca are almost uniformly happier than those without, so it is now in my standard playbook for phals.

I definitely would not put Perlite in the same category as sphagnum. Sphagnum holds about 18x its weight in water, and when fully saturated seems to lead to anaerobic conditiions quite easily.

Perlite holds about 3x its weight in water, and even when wet traps air bubbles in its structure, and since it is volcanic glass does not decay, although it can be crushed.

Vermiculite holds about 5x its weight in water, like perlite also traps air in its structure, does not decay (but does compress and break apart over time), but unlike perlite the water is also absorbed into the structure of the material and doesn't just sit on the surface, so it is moist but not wet and releases its moisture a little more slowly, essentially sustaining the hide humidity around the roots while still being fairly dry.

I also wouldn't characterize vermiculite as "soil", as vermiculite is naturally well aerated compared to most soil.

FWIW, I dont think i would use vermiculite for many orchids. Terrestrial ones like Macodes and Ludisia and other plants that really want a moist root zone where I dont want to use sphag as it gets too wet and too cold in the winter here are the only ones I would use it on. I have put it in my with my Paphs (<5%), Ludisia and Macodes (~25%), but nothing else. I might try it with some of my fine rooted oncidiums in the future tho, mixed with perltie and fine bark i think it might do well.

I am still learning this site, attached is an image of my vermiculite research. There are also a lot of academic articles on this. There is an excellent one comparing the physical properties of different ratios of perlite, peatmoss, and vermiculite, which gives a really good insight I dont know how to post links here, so try searching for 263996989_Physical_Properties_of_the_Horticultural _Substrate_According_to_Mixing_Ratio_of_Peatmoss_P erlite_and_Vermiculite
you should find a research paper by Hyuk Suu Kim and Kyehoon Kim which has tons of low level details.

[WaterWitchin]

I've used vermiculite when I used to grow in a bark mix for paphs and phrags, and some of the finer root oncidiums. Was doing a bunch of repotting and had run out of perlite for the mix, thus vermiculite. Turned out to be better for the mix for them than perlite.

As an aside, I used to use perlite for my asparagus beds. Switching to vermiculite was a real game changer for the better. Same for starting seeds.

---------- Post added at 07:10 AM ---------- Previous post was at 07:04 AM ----------

Originally Posted by YetAnotherOrchidNut

... I dont know how to post links here...

OrchidNut... when you post a message, look above and you'll see a little Earth symbol (blue ball) with a sort of paperclip thing in front of it. If you click on that, a bar/box comes up. Cut and paste the Url into that bar, hit return. It will add the site into your post.

[Shadeflower]

Originally Posted by YetAnotherOrchidNut

I definitely would not put Perlite in the same category as sphagnum. Sphagnum holds about 18x its weight in water, and when fully saturated seems to lead to anaerobic conditiions quite easily.

Perlite holds about 3x its weight in water, and even when wet traps air bubbles in its structure, and since it is volcanic glass does not decay, although it can be crushed.

What a substrate does on paper is always very different to how the orchids react to it.

I think perlite hold more than 3 times its weight, maybe 3 times its volume is correct.

It is true that moss holds 18 times its weight but one thing one has to realize using moss is if one does soak moss everything will rot.

So yes moss holds far more water than perlite, perite one can soak and it will dry out fast enough again, one cannot do the same with moss , ever. It would absorb 18 times its weight and would not dry out.

But no orchid grower does this. If you compare moss in the way an experienced grower uses it then moss and perlite acts in simila ways on how the orchids will grow in it.

I think it's good to have different opinions, we all make different conclusions about the substrates we use and I can completely understand those points.

Like I said for terrestrials I'm sure as everyone has said vermiculite can be used, but on paper it does absorb twice the water that perlite absorbs and that means half the air that perlite holds.

You can say the paper says otherwise but that is how it is, the more water a substrate holds, the less air it holds and vice versa.

That is why i like perlite because it is roughly 20% perlite, 40% air and 40% water when saturated.

vermiculite would be more like 20% verm, 60% water, 20% air when fullly saturated.

In a mix you can achieve any ratio one wants. Vermicultite by itself probably holds too little air long term but like Dustin I have too little experience daring to use the stuff and would also be interested in the results

[YetAnotherOrchidNut]

Originally Posted by Shadeflower

What a substrate does on paper is always very different to how the orchids react to it.

I think perlite hold more than 3 times its weight, maybe 3 times its volume is correct.

FWIW. I did it by weight. I took two identical small sized (~100ml) orchid pots. I placed a small piece of paper towel to act as a filter at the bottom of each one. I filled them to the rim with perlite and vemiculite respectively. I weighed the pots separately, and then again with the media. I then thoroughly soaked them, that is they sat/floated in water for ~30 minutes, I then let them drain for ~30 minutes as I would one of my plants and weighed again. I used a digital scale with 0.01 gram accuracy.

The dry weight of the perlite was 10.55 grams, the wet weight was 29.70g. (These weights omit the weight of the pot itself.) The numbers for vemiculite were 9 grams dry, 42.9 wet.

I weighed them daily for 7 days. At the end the perlite was essentially dry at 11.5grams, and the vermiculite was still holding more than its weight in water at 21grams. They lost about 2-3g of water a day due to evaporation. I did the experiment at the end of spring before summer got really warm. I did not alas log the temperature. :-(

If you have a scale and a bit of patience you can verify this yourself. Don't trust my results, your perlite and vermiculite might be different grades or composition!

I do agree that the fundamental of the media alone are a bit irrelevant. The media and the watering regime and the climate need to be in harmony. I have learned the hard way that high levels of sphagnum and my watering regime are a good recipe for dead plants, so I use it super sparingly. I use perlite much more readily.

My main curiosity about vermiculite is that its physical properties seem like they would align with a bunch of orchid and tropical plant scenarios so I was curious why I didn't see more references to it. I wondered if there was some hidden catch. So far it seems not. I will report back on my results, and let you all know. Until my plants have been happy for a couple of years it is still just an experiment.

I plan to redo this experiment soon, and more carefully. Ill post my results when I do.

[DavTom]

Hi HBN!

Nice to see you again (we exchanged a couple of messages a couple of years ago about one of your great videos you did covering flasking). I have now a bit more info/results about what I am doing with lava rock and other things I apply to a few Phals from my planted aquarium experience. I would really appreciate if you could have a look at this thread
"Is this ordinary or extraordinary result?" here in the orchidboard in the introductions and share your thoughts. It would be very valuable for me.

Thx.

Davide

[TheOrchidBaroness]

All of those behbies!! Gaaaa so cute! Good job on fighting mother nature and having your little jungles despite inhospitable conditions!