Hausermann's answer on tightly packed sphagnum moss

[tmoney]

thanks for the info! as our collection grows this idea about packed moss growing has been constantly creeping back into the realm of possibility. also, reducing our water consumption is becoming more of a priority, as well as reducing the amount of time spent watering.

currently we use around 50 liters every week, just on our orchids. and it takes me about 4 hours to do the process each weekend, both of which will become unsustainable when our seedlings get bigger and require their own pots.

so yeah, we r invested in learning this method and making it work in the home....thanks again. we will keep watching this thread for any other insights!

[Roberta]

Originally Posted by Clawhammer

I don't understand how it is hydrodynamically possible for the middle to be bone dry while the outside is still moist.

Once dry, sphagnum becomes rather hydrophobic. To re-wet it, significant contact time is needed. If you soak it, it'll retain the moisture a long time. So that's what makes it tricky. If all the conditions that a commercial grower uses are met, it can be a great medium. For hobby growers, that's not necessarily so easy to do. Personally, I mostly grow Phals in bark If I use sphag, generally in a basket - so that there is really good air flow, as the sphag dries it pulls in air. I do a lot of sphag + basket for my outdoor-growing orchids. They can stay quite damp, but happy because of that air exchange. This works for me under my conditions, which are very different from those that most people have to deal with.

[Clawhammer]

Originally Posted by Roberta

Once dry, sphagnum becomes rather hydrophobic. To re-wet it, significant contact time is needed. If you soak it, it'll retain the moisture a long time. .

Right, but the wet outside sphag would be against the inside sphag for a long time, wetting the inside sphag. For me, the moisture is uniform. I can touch the top and it is the same dampness as when I poke my finger into the drainage hole. Not doubting this can happen, I just don't get it.

I went fully in on tight sphag in terra cotta for my phals after a lot of experimenting. It was pretty obvious from the get go that my plants loved this treatment in this environment. I've always used bottom heat so maybe that makes a difference. Every one of these go from wet to fully dry in five days like clockwork.

[IMG]Untitled by Eric, on Flickr[/IMG]

---------- Post added at 11:20 AM ---------- Previous post was at 10:38 AM ----------

One last thing and then I will shut up. I am a big fan of keeping the media consistent if possible when repotting, as changing media types usually initiates a mass root die off. Since most phals come from the nursery in sphag, continuing in sphag generally minimizes a setback from repotting. It also facilitates the "drop and plop" if the original sphag is still in decent shape, so minimal root disruption

[Dimples]

I don’t know the full scientific details about why some medium can stay bone dry when in contact with wet/damp medium, but I’ve unpotted enough plants to know there can be pockets of wet next to pockets of dry in pots regardless of what the mix is. With potting soil, when up-potting plants it’s best to rough up the exterior of the rootball a little bit to prevent a boundary zone, so it makes good contact with the new mix around it. If you don’t do that, the water can flow around the outside of the original rootball without wetting it, giving you a bone dry core and a wet/damp outside. Newer mix absorbs water much easier than older mix for a few reasons, so the water stays put. Maybe there’s something similar happening when each successive layer of sphagnum is wrapped around the old ones. The newer layers may not have good contact with the older layers, especially if there’s a lot of roots in between.

[estación seca]

Yes, the dry might be the root ball from the previous potting. In other words, old medium. It's a good idea when repotting orchids in packed sphagnum to get them fully wet, then carefully remove all the old moss.

[Dusty Ol' Man]

Originally Posted by Clawhammer

I don't understand how it is hydrodynamically possible for the middle to be bone dry while the outside is still moist.

That's the way I understood it as well. But the fact is that is what I found. I'm still scratching my head over it.

[Leafmite]

I really think that how the moss is used, like any type of medium, really depends on the environment in which you are growing your orchid, the type and size of pot you plan to use and the type of orchid that is being grown. There really is no 'one size fits all'. It is important to use AAA or AAAA long strand, good quality NZ sphagnum moss and not the poor quality stuff.

I have been using it loosely packed for my Zygos, a Dendrobium, the Cync. Wine Delight, and two Cattleyas with good success. Now that the moss has gotten more expensive, I am going to return to red lava rock but probably amend it with something cheap that retains water and doesn't decompose quickly.

[BulboLoverNL]

I found this very interesting information about the packed spaghnum. in the youtube video’s by Dani from orchidgirl she is always very firm on draping spaghnum loosely if using it and not packing it is. She lives in a hot and dry climate.
When I bought my mounts from a nearby nursery they where “cages” with firmly packed spagh. I didn’t quite get it as I was always told bot to pack spagh, but the mounts work like a charm! The bulbo’s love them. I water them on sunday, then spray them once by thursday, and then water on sunday again. And this is for bulbo’s that don’t want to dry out. It has been such a low maintenance I’m 100% getting more!

So I was wondering, it was mentioned a few times here that packed spagh can work depending on the environment, may I ask what that environment is? I just want to make sure I’m not going to run into problems later.

My specs are 50-70% with 16-22°C right now in fall, but drops to 40-60% with 18-31°C in summer.

What other orchids could grow well in tightly packed spaghnum basket/cages?

[Leafmite]

If the way the moss is packed around the roots works well for your Bulbos in your environment, there is no reason to worry or to change anything.

[BulboLoverNL]

I have only had them for a month or two, so no idea if they will work out year round. It gets much dryer when the weather starts warming up