Growing in damp sphagnum

[Linus_Cello]

You can find larger pots at nurseries that sell plants for outside ponds. Waterlilies and such come in them.

Oh, those type of pots. I use them for my calopogon (swamp pinks). I was thinking of something else. Those would be good for a lot of airflow.

 

[The Orchid Boy]

...... Probably my big attraction to sphagnum is that I can water everything and be gone for 8 days and not have to worry about anything being too dry or arranging for someone to try and water. The literature on orchid growth in sphagnum shows a number of benefits, but you have to carefully control the downsides to get these benefits.


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I love that about sphagnum too. I can go away longer without having to worry.

 

[Erythrone]

I am another 100% NZ sphagnum grower for my Paph, Phrag, Phal, Milt, and Catt plants. I am an indoor grower under LED lights. I think it was Ray some other place and time who made the point that it isn't wetness that is the downfall in sphagnum, since we know that orchids do well in S/H and even in pure water culture. It must be chemical imbalances that lead to trouble over time as the sphagnum is actively messing with electrolytes.

I feed at 40 ppm N with K-Lite with KelpMax at only 1:800. Like Rick, I need to add tap water to my fertilizer mix to obtain enough total alkalinity. I monitor the effluent of pots periodically for EC and pH. I also repot my plants at least once a year and often twice. All of these things are difficult to do with a large collection, but I can do it with about 100 plants. I also water each plant only when the top has gotten to the right degree of dryness for the type. I rarely see root rot.

There may be no perfect medium for growing, only one that works with all of the other conditions of the growing area.


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Terry do you feed every time you water your plant?

 

[dodidoki]

I had terrible results in sphagnum until I realized that the key to using it is to not soak it until water runs through. Now I'm getting very good root growth in plants that are growing in barely damp loosely packed sphagnum. I use a fine nozzle on a pump-up sprayer to just moisten the top 20 mm of the pot (3/4"), without getting any water/fert on the plants themselves. I do this every 4-5 days for plants that are growing in plastic pots; more frequently for plants in net pots. I'm growing at home, where humidity right now is 70-80% (I don't like or use air conditioning).


My experience is that it works at few plants,but does not work at any others.

Eg. barbatas are growing very well in SPH with K-lite ( mastersianum, zieckianum, violascens), others got rot.

Others likes SPH on surface to produce new roots ( especially phrags and hookerae, purpuratum).

Others hate SHP ( eg. hirsutissimum and insigne like spec.)

 

[orcoholic]

What's SPH?

 

[gonewild]

What's SPH?

SPHagnum moss?

 

[The Orchid Boy]

Just a little FYI.... Everyone knows that 'sphagnum' is pronounced 'sfagnum' like 'sphere' is pronounced 'sfere', right? I've heard it pronounced incorrectly a lot, I used to pronounce it incorrectly. I'm kind of a grammar/ spelling perfectionist.

 

[terryros]

I do feed every time that I water because I am using low strength of fertilizer (40 ppm N). I think it is important to flush through the medium every time to not let electrolyte or pH imbalances build up. Ray has shown what happens to the pH in S/H plants as the solution sits for a few days. My fertilizer solution has a pH of 6.9 because it is a 50:50 mix of RO and my tap water (to add back some alkalinity). I think that monitoring the effluent from a pot (about 50 mL of RO water poured over the medium surface about an hour or two after fertilizing, collecting the effluent in a dish) for both EC/TDS and pH helps to spot when the medium may be outliving its stay. I then repot.


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[ALToronto]

I may have to rethink my method. I'm going to take the plants out of solid plastic pots and put them into net pots. Then flush through the sphagnum.

 

[shadytrake]

I have a hubby who is a chronic over waterer so I moved anything that was in sphagnum to baskets with lots of airflow.

Ones that like it on the drier side got moved to Orchiata/sponge rock/charcoal mix in a clay pot. I don't have many left in plastic unless they are net pots. The few I have left in plastic are either in transition or have great root growth so no need to move at this time.

 

[naoki]

I do feed every time that I water because I am using low strength of fertilizer (40 ppm N). I think it is important to flush through the medium every time to not let electrolyte or pH imbalances build up. Ray has shown what happens to the pH in S/H plants as the solution sits for a few days. My fertilizer solution has a pH of 6.9 because it is a 50:50 mix of RO and my tap water (to add back some alkalinity). I think that monitoring the effluent from a pot (about 50 mL of RO water poured over the medium surface about an hour or two after fertilizing, collecting the effluent in a dish) for both EC/TDS and pH helps to spot when the medium may be outliving its stay. I then repot.


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Thanks for the info. I think your pour through measurement method is what Yao et al. (2008, HortScience 43: 2167-2170) recommends (except they recommend 60ml instead of 50ml, but this shouldn't make a difference). I was just reading this paper to understand different methods of EC/pH measurements. They get pH of 3.5-4 from sphag (and EC somewhat depends on conc. of fertilizer). When do you decide that you need to report? Any threshold values of pH/EC you use?

 

[terryros]

The pour through method has been published by several different authors and I don't know who was first. You just need to get enough effluent to run the analysis and that just depends on the size of the EC/TDS and pH meters you are using. Larger pots require most RO poured over the top than smaller pots. I tend to always test a medium sized plant/pot.

I think most written information would support wanting a pH of the effluent to be in the 5-6 range for most orchids. To achieve this with pure sphagnum, there must be enough alkalinity in the medium. Rick has talked about adding certain types of sand to his mix. Infrequently I have tried some pellitized dolomite lime. I decided to make sure that my fertilizer solution had enough alkalinity in it which is why I no longer use pure RO with K-lite, but a 50:50 mix with my tap water. The pH of my effluent has come up with this.

The EC that is optimal seems open to some debate and probably varies with types of orchids. Using the most common units in which EC is measured, it looks to me like you would want to stay under 0.5 and some advocate much lower than this. To achieve this, you have to use a dilute fertilizer solution, probably with every watering. If the EC starts to get up to the cut point you have defined, you either have to repot, or you can try several sessions of flushing with just water. I wouldn't do this with pure RO because of the pH problem that I am trying to avoid. My tap water has an EC of about 0.25 so I would probably try that.

Honestly, I really like to repot orchids with sphagnum. I like the feel, the smell, and how it goes in between the roots and settles the plant. I pot only firm enough to just hold the plant. Thus, any excuse to repot lets me look at roots and feel good about the environment of the roots. I can only do this because I only have 100-125 plants. It would too time consuming with a large collection in a greenhouse.


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[Stone]

The pour through method has been published by several different authors and I don't know who was first. You just need to get enough effluent to run the analysis and that just depends on the size of the EC/TDS and pH meters you are using. Larger pots require most RO poured over the top than smaller pots. I tend to always test a medium sized plant/pot.

It is vital that when using the pour through method (and its not as accurate as the saturated extract method. Pour gives readings (for EC) about 1.5 times higher than SE so you have to allow for that if you are comparing the two) that you use the standardized method each time otherwize your redings may be all over the place. (for example, just a little more water will reduce your EC and either raise or drop your pH readings very sharply). The standard is to slowly pour enough water to catch 50mL under the pot regardless of pot size. This should be done 2 hours after normal watering.