For those of us who hate watering
 

Hi everyone,

I'm on a quest to find a better potting medium. I've grown orchids for about 6-7 years now, and for me, the trickiest thing to manage is the choice of potting medium. I don't believe in universal rules for potting; while I understand the need for guidelines in novices and beginner growers, I've come to appreciate that success comes from finding the perfect match between medium and growing conditions. For instance, I have never had a single plant grow well in bark. Conversely, I've tried dendrobiums and phals in straight sphag with decent results. As a chronic underwaterer, sphag seems to work the best, although I do have problems with it compacting and getting gross and soggy after a while. Coconut works amazingly in small pots, but in larger pots, I run into the problem of poor moisture distribution, with the top coconut bone dry and the inner core wet and soggy.

Recently, I went to an excellent talk by lycaste expert Henry Oakeley. While discussing mediums, he touched on how bark has never worked for him - how the top of the bark is dry but the bottom is wet, and so you end up with a ring of roots circling the top of the pot and a ring of roots circling the bottom of the pot, trying to escape. He uses a sphagnum-perlite mix that can stay pretty much uniformly moist/dry so there is no guess work involved with watering. I know that S/H generates a NON-uniform moisture gradient, so that is certainly a different take on things. Someone recently mentioned a grower who plants cattleyas in a coco-peat/perlite mix. Definitely far more dense than your conventional well draining bark mix.

My question is, if you are also a chronic underwaterer, what potting strategies have you adopted? If you live in a dry environment but can't afford the time to dunk everything every other day, what do you do? And how important exactly is moisture uniformity in a potting mix?

(obviously it's impossible to separate potting mix from plant specific needs either, but lets take that out of the equation for now)

I can't agree with you more about the bark. I hate the stuff for all the reasons you mentioned and more.

In many instances moisture uniformity is vitally important. That's one reason i repot plants into sphagnum moss. It is a very uniform mix, much like a sponge. S/H is only non-uniform if the top dries out quite quickly or if the water can't wick through the pot easily.

You can minimise this problem by either making the particle size smaller, using a medium with greater water-holding capacity, or top-dressing the pot with something (pebbles, sphagnum moss) that lowers the evaporation rate at the surface.

I kill 10 birds with one stone and use 100% perlite in a S/H setup. It holds a lot more water and provides for more even watering through the pot than LECA. I top dress it with pebbles to minimise the algal buildup which comes with the added moisture.

I do use 100% LECA in some pots as well. In very large pots i top dress those with pebbles too, but not for the algae but to lower evaporation rate. I use clear pots and i can see by the condensation through the pot that the whole of the pot is fairly uniformly moist when you top dress in this way.

For a dry environment, and for complete watering control, some adaptation of S/H works very well for me.

Thanks for the reply, undergrounder! With 100% perlite, do you find that there are problems with the media being too compact? Everyone always emphasizes air space in between media chunks...how important is that, REALLY? Do you use a larger sized perlite? The stuff I have is pretty fine (roughly 1-2cm in diameter or less). I have some dendrobiums that don't seem too pleased with me, which I'm going to try with a new mix.

No i don't have a problem with media being too compact or small particle size with perlite. And i don't think the amount of air is very important in media once the roots have adapted, but plenty of people will disagree with me. 1 - 2cm sounds like big perlite, mine is on average about 0.5cm.

But i wouldn't use it for repotting Dendrobiums because as far as repotting goes, it will probably be too wet for Dens that have been grown in traditional media. It's like all semi-hydroponics, it will kill off old root systems that have been grown fairly dry, and only really works with new roots, or roots grown in wet media like sphagnum moss. As an S/H alternative to LECA, it has benefits and drawbacks. Major benefits are the superior water holding capacity, which equates to better water distribution through the pot over LECA. This also means it accumulates salts slower than LECA. It's also cheaper. Only major drawback is the 'dust' which needs to be washed out before use (although only once, unlike LECA). Because it is wetter, it does attract algae more than the LECA though. I use pebbles on top to stop light getting to the algae. Finally, when its wet it 'sticks' more than LECA, which makes it more difficult to work with when wet.

So in my dry environment i use LECA with a top-dressing of pebbles in my large potted plants, and perlite with a top-dressing of pebbles in my small potted plants. And treat both as normal S/H.

There are MANY ways to grow - that is very obvious to me from growing orchids and reading their care over the years by others.
For me and - in my specific growing conditions - (indoors under lights with temp ranges and humidity controlled within specific values) I have found that wooden baskets with a mix of medium bark, lava rock, charcoal and cork gives me great root growth, good plant health and predictable flowering. BUT, that's just for me in my specific growing conditions for what it's worth.

Orchids can be grown in almost anything but its the grower that adapts. Pearlite or sponge rock grows thing fairly will but gives me astma so I adapted. I am using a combination of Stalite Gravel (heat expanded shale) and CHC now and am delighted. CHC
increases or decreases according to type of plant but alway the mix is 50% Stalite or more. One friend of mine waters daily - an artist - it gives her a break from her painting. Her media of choice is Aliflor. It suits her needs but not mine. Stalite holds 30% of its weight in water and is not as heavy as just Gravel - a lot like the aliflor. I gave up on bark years ago. Some years when you can get good fresh bark its ok but some years the stuff is just plain poor. I personally think moss is the pits. It does well for a while then suddenly goes bad and if you do let it dry out completely its the pits to get wet again. Good luck with whatever you use. There is no real right or wrong potting material - just a right and wrong way to use it.

I use 100% LECA (Hydroton, to be specific), which tends to do fairly well. The problem I run into is that the smaller containers actually dry out with my circulation system (so it actually seems like more of a problem with that, which I'm addressing). Of course, certain plants like it more than others... My phals are in heaven. On the other hand, I have a Den. tobaense which seems intent on lulling me into a false sense of security by growing, then dropping leaves, then growing, etc.

I must admit that this is a slight problem since my orchids were all previously on my balcony. I have a shelving system lined with shade cloth that works well. However, with the threat of winter and cold nighttime temperatures I've brought everything inside. This means that I can't simply water everything the way I did when it was outside (I could, but my carpet would be ruined and I get the feeling the apartment complex might get upset.)

I've also found that a great many of my phals thrive when placed in a wicker basket filled with lava rock. I mean the cheap lava rock too, the kind you get several cubic feet for only a couple of bucks. I had a rescue Phal placed in this set-up for only about 2 months... when I took it out to check on it, the entire basket was full of roots... some of them nearly 3' long! All I did with that setup was mist the plants daily, the pores of the lava rock held plenty of moisture throughout the day without overwatering. I'm an underfertilizer, so salt buildup wasn't a huge issue with that plant (but I did just run clean water through every couple of weeks).

I haven't had the same luck with other plants doing as well in straight lava rock, but at the same time I haven't really tried. I've been "rescuing" phals going out of bloom from the grocery store (some in truly horrible condition), so I've been able to experiment the most with them.

I only use CHC with a 10 to 16 mm lump size for my Cymbidiums , but it must have the coir strands included, This wicks quite well as my plants either stand in saucers of nutrient or have internal reservoirs. Just recently I have been adding a wetting agent to my feed water every third watering and this helps with the top portion of the larger pots drying out as it lowers the surface tension of the water which in turn improves capillary action .

I'm not any help with input on the potting medium, but I would like to know where I can find out more info on root behavior and what my roots are trying to tell me. I have been told that if roots, say with a phal, grow up and away from the potting medium, that it is a sign that they don't like the potting medium. I have orchids with roots that circle the bottom of the pot, but also have roots every where else....I thought it was a sign of the roots being happy and part of the process of becoming root bound. So can someone point me in the right direction where I can find out more info on this subject? Thanks for any help...and I am really enjoying this thread, I find it very interesting!

Becca,
My observations:

I was given 4 phals last spring by a friend who had infrequently watered them since she had gotten them. They were [I]very[I] dry. The new roots they had grown were all very long arials (sp?), nothing had grown down into the pot.

I wondered at the time if they were looking for moisture (in the air) since there wasn't enough for their liking in the bark.

I got another phal that was growing in sphag. The roots in the middle of the pot were rotted but new ones had gone down the insides of the pot and were circling. It looked like they were finding a not-so-soggy place to grow.

My phal roots that are happy seem to all grow down into their pots, very few above ground, and they go everwhere they can.

For what it's worth,
Maureen