Sphagnumaphobia

[K-Sci]

Sphagnum seems to prevent root rot and could reduce my watering frequency. Nonetheless, I'm afraid to use it for orchid potting in general.

- The capture basin above the sphagnum and below the rim of the pot fills when watering. The water is retained and typically 100% soaks into the media. The size of this basin has to be managed or watering will result in very different media wetness for different plants.

- For some plants, the root tips die the moment the tip touches the sphagnum, presumably due to fertilizer salt buildup on the evaporation surface (I use RO so it isn't my water). I had one particularly sensitive phalaenopisis go for years with all the new roots stopping at the media suface.

- Sphagnum absorbs many times the amount of solution versus bark when fertilizing. Yet I've never seen fertilizing instructions advise to use less fertilizer with sphagnum.

- Large plants require watering very infrequently versus small and those in bark. Tightly packed sphagnum requires a different schedule than loose sphagnum. With sphagnum I have to inspect every plant individually before watering.

- Spagnum requires repotting every 1-2 years vs. 4 years for the Orchiata/LECA mix I use for most orchids.

So what do all y'all do to get around some of these problems.

-Keith

[rbarata]

I don't have many plants in sphagnum but, as a general rule of thumb, when the top layer is dry and crispy, then it's time to water.
If you want to control better the amount of water you put into it (i.e., without soaking completely the pot) use a hand mister.

[estación seca]

It works well once the gardener learns to use it. It may be less forgiving of overwatering. It may not be a good choice for warm growing orchids in a typically cool home environment.

[SADE2020]

Hahaha, I feel you are a tricky medium.

I don't have big plants in Sphagnum, only small very delicate, and special genuine. But I think the humidity and airflow level plays a big role. In my case, I need to be constantly watering anything in full Sphagnum since I have a lot of humility but much more ventilation and it dries very fast.

So, I totally agreed with ES, you need to "learn" your gameplay with Sphagnum base in your environment.

[SouthPark]

It's probably about consideration of what happens with sphagnum over time --- not just on average, but at the various depths of the pot.

When roots get longer and occupy more of the pot ----- and the state of the sphagnum itself over some period of time. This needs to be considered for any sort of of media. But certainly - with sphagnum --- and organic sort of media, maybe the amount of uncertainty on media state within the pot (with time) might be more than with other sorts of media.

It certainly comes down to keeping the system under control ------ for the benefit of the orchid (including knowing about when to change old sphagnum to new sphagnum etc) --- and how that is done certainly depends on whoever is looking after the orchids.

And also depends on the sort of orchid we have - with the sphagnum. Some orchids may be tougher than others (and also some roots - adapted or not adapted - can be tougher than others).

[isurus79]

You can get around the fertilizer burn situation by changing the media every other year, which of course brings a whole new suite of problems! However, for plants that aren't super sensitive about root disturbance (e.g. most Phals, Phrags), this isn't necessarily a problem.

[Roberta]

My growing conditions are very different from those who grow indoors. But I use quite a bit of sphag, even for some moderately large plants, but mostly I use it in baskets (net pots). So there is not a lot of dead air, they dry out (at least to "damp") pretty quickly - and I water frequently.(like daily in summer, about every 2 days in winter) Pretty much all with RO water. But again the outdoors situation - lots of air movement (complements of Mother Nature) and generally humidity that is moderate enough to encourage some drying - which also increases airflow. I also use fairly long-fiber sphag - like BestGrow Sphagmoss Premium when I can get it. The long fibers don't hold as much moisture as types that contain more "spongy material" and less fiber. I have taken my cue from the plants that I get from Andy's Orchids in baskets (which is mostly how I get them if they aren't mounted)... the medium doesn't get changed very often , nor need to be. When it gets really old, it just turns to dust and falls out of the basket, then it's time to re-do. But again, these are plants that have been growing outside in a climate similar to mine.

So sphagnum can be a very good medium - under suitable conditions. Under YOUR conditions, if you want to try it out, try it on just a few plants. And keep in mind the objective in selecting the plants to experiment on - Damp but airy. If you can't get the second part to work for you, then look for other media better suited to YOUR conditions.

[Leafmite]

Use a good quality NZ sphagnum moss, either AAA or AAAA long-fibered moss. This is very important. I have my Phal bellina (warm grower) in a basket pot stuffed with the moss and even in the cool home during the winter, I have not had any trouble with the moss. If I had more money to spend on the orchid hobby, I would probably put all my orchids in the moss but the good quality moss gets expensive.

The cheap NZ moss is good to mix into potting soil to help lower pH.

[Fairorchids]

If water pools on top of the spaghnum when you first water, then you have:
A. Packed it too tight in the pot.
B. Watered too late, after it dried out.

I use a lot of spaghnum (all Paphs, Dendrobiums, reedstem Epidendrums & Vandaceous, and Catts up through 3" pot size). I mix the spaghnum with some bark/charcoal (usually about 20-25%), and only pack the medium fingertip tight. This allows adequate air circulation through the pot (or net pot).

I always water before anything has fully dried out. And, I pour on water till I see it running clear through the drain hole.
This includes mature Cattleyas, which are potted in:
C.1 Coarse bark/charcoal/perlite mix in clay pots (4" size & up)
C.2 Coarse LECA (Aliflor) in metal mesh baskets (8" & larger).

NOTE: You can water mature Catts daily, provided they are in a coarse enough medium to allow the necessary air flow. In summer I water 3 times a week, and when I water I drench the plants (hose with high flow wand).

Re fertilizer
We fertilize every 2 weeks. That means that we water without fertilizer 3-6 times in between, Since we always drench the plants, this washes away any excess fertilizer salts.

Re Bark (Orchiata)
Virtually all orchids outgrow their container in 2-3 years. Thus, I do not see any reason to spend $ on a 'premium' bark. Also, I have had people tell me, that while Orchiata does last long, the pH starts to change after a few years.

[Ray]

Until I figured out how to use it in my growing conditions, I had a serious “love/hate” relationship with sphagnum.

For indoor growing, I found that keeping it relatively loose in the pot and watering from the bottom was the key. My experience in the greenhouse was to use it in baskets, as Roberta related.

When I moved to NC, where my plants are outdoors 7-8 months of the year, I found it to work better with the kind of flooding Kim documented, but for me, the stuff (NZ AAA) only lasted about 6 months, so I switched to Grodan rock wool cubes as a substitute (which I now use in a blend with LECA, as the cubes compacted too much for my liking).

Speaking of compacting, that is one thing I have never been able to wrap my mind around: how do nurseries get away with really compacting the sphagnum? More compact means less air space, so I’d think that the moss would saturate and suffocate the roots, drying very slowly. What am I missing in that equation?