# Mosses, weeds and ferns... Bad or good?



## Brabantia (May 6, 2013)

I cultivate Phragmipediums on a substrate made of equal parts clay balls and rockwool cubes.I add to the fertilyser solution (Rain mix) 0.2 ml/1L (1/6 tsp/1gal) of seaweed extract. pH of this solution is adjusted at 6 with tap water. Mosses, weeds and even small ferns grow on the upper surface of the potting. It is very attractive but is this good or bad for the culture or for the health of the plant?


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## gonewild (May 6, 2013)

Brabantia said:


> I cultivate Phragmipediums on a substrate made of equal parts clay balls and rockwool cubes.I add to the fertilyser solution (Rain mix) 0.2 ml/1L (1/6 tsp/1gal) of seaweed extract. pH of this solution is adjusted at 6 with tap water. Mosses, weeds and even small ferns grow on the upper surface of the potting. It is very attractive but is this good or bad for the culture or for the health of the plant?



By definition "weeds" are bad. oke: so you don't want the weeds.
Mosses and ferns indicate an environment that Phrags like.


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## Stone (May 6, 2013)

Definately get rid of them. They will reduce air induction into the medium, leading to stale conditions in the pot and fast media break down. Throw out the top few cm of mix and top up with fresh.


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## gonewild (May 6, 2013)

Stone said:


> Definately get rid of them. They will reduce air induction into the medium, leading to stale conditions in the pot and fast media break down. Throw out the top few cm of mix and top up with fresh.



Brabantia's media consists of only clay balls and rock wool, so there is no media breakdown problem.
Personally I think the moss and ferns will give Phrags a better root environment by adding a little natural organic matter.


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## ehanes7612 (May 6, 2013)

seems my phrags do really well in media that has ferns and moss in them


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## Rick (May 6, 2013)

I also agree that the mosses in particular are great indicators of good pot conditions. Sometimes I think the ferns can get out of hand, and end up periodically ripping them out. In my GH they seem to take off in baskets more so than pots, and sometimes get so thick that it seems like the roots are "strangling" the orchid roots. But usually I let them be if they stay small or are unusual species (no telling what pops up from sphagnum moss sometimes).

"weeds" especially clover is a pain, and doesn't even look good.

One thing that may be an extra bonus with mosses, is that they often form relationships with BG algae that are nitrogen fixers. So there may be at least one worthwhile chemical association with mosses in the pot .


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## mrhappyrotter (May 6, 2013)

I leave the mosses because I think they are attractive and I've not seen any evidence that they cause any harm (I grow in a similar mix of mostly rockwool).

I pull the ferns when they get too big. The concern being that they grow faster than the phrags, can crowd them out, and out compete them for nutrients.

I also pull the other stuff that pops up, like oxalis, because I don't like the way it looks and general concern that if the oxalis dies, the dying, rotting roots might cause issues for the phrag roots/mix.


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## gonewild (May 6, 2013)

mrhappyrotter said:


> I also pull the other stuff that pops up, like oxalis, because I don't like the way it looks and general concern that if the oxalis dies, the dying, rotting roots might cause issues for the phrag roots/mix.



Never let oxalis grow. It is a bad host for pests, especially spider mites and white flies.


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## SlipperFan (May 6, 2013)

Moss like. Weeds and ferns, not so much!!!


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## SlipperKing (May 6, 2013)

I'm for the co-existences with the mosses and ferns too. All the plants out of Hawaii come with mosses in the pot and these are the best grown plants by far of any vendors I buy from. AND every in-situ PIC I've seen of Paphs and Phrags I see mosses and ferns!


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## lepetitmartien (May 7, 2013)

Mosses are fine as long as air passes thru.

On ferns, I think a little lecture of Sue Bottom with pics may enlighten you.
http://www.staugorchidsociety.org/PDF/FernsandOrchidsDoNotMixbySueBottom.pdf

There's something called competition…


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## Brabantia (May 7, 2013)

lepetitmartien said:


> Mosses are fine as long as air passes thru.
> 
> On ferns, I think a little lecture of Sue Bottom with pics may enlighten you.
> http://www.staugorchidsociety.org/PDF/FernsandOrchidsDoNotMixbySueBottom.pdf
> ...


Thank you for the reference but fortunately I am far from this situation.


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## paphioboy (May 7, 2013)

No problem with mosses and ferns. I let them grow as they like 



> On ferns, I think a little lecture of Sue Bottom with pics may enlighten you.
> http://www.staugorchidsociety.org/PD...ySueBottom.pdf



Just read the above article. IMHO, there is no point splitting the established dendrobium root ball. Plus, that fern looks like a rabbits foot (Davallia) whose roots I use as media for paphs and bulbos..! There is no concern that orchid roots cannot 'breathe' if drainage is good and media is not soggy. If I were in the author's shoes, I'd just unpot it and place the whole root mass into an empty basket. The plant looks like it is perfectly healthy and there is even a nice new growth..


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## limuhead (May 7, 2013)

I pull the weeds and ferns. Fern roots can strangle orchid roots and compete for air and nutrients(as well as weeds). If I see a plant I am selling with a few ferns I usually charge extra for the 'companion plant'. :rollhappy:


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## gonewild (May 7, 2013)

limuhead said:


> Fern roots can strangle orchid roots



Can you explain how fern roots "strangle" orchid roots?
This has been mentioned several times.
I'm not disagreeing, I just would like to understand how orchid roots are strangled and how you know fern roots do it.


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## NYEric (May 7, 2013)

Weeds = nasty, ferns = Not so nasty, Moss = nice.


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## PaphMadMan (May 7, 2013)

No one has commented on the liverwort in the first picture. It appears to be Marchantia polymorpha, which is recognized as a serious greenhouse weed in some cases, and very hard to control. The kind of thing that might not be any harm to a mature plant, but if it got into a compot could completely overgrow the seedlings in a matter of weeks if it wasn't noticed. Other liverworts are not likely to be as serious a problem. Personally, I love the way ferns, mosses and liverworts look growing among the orchids, and I doubt they do much harm in most cases. But you do have to consider if this is something you want to let spread in your environment if it could be a problem in the wrong place.


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## Stone (May 7, 2013)

Leave a layer of moss on top of the pot and sooner or later the roots will die.
Ferns are ok for a little while but there roots will eventually smother the orchids roots. If you have the conditions in which mosses and ferns grow, thats enough. You don't want then in the pots! You don't want a condition in which the only air entering the pots is through the drainage holes. They may look good but they serve no useful purpose at all except maybe if an orchid is in too large a pot, a fern growing with it may keep the mix in a better condition until the orchid catches up. But orchids should't generally be overpotted anyway.

This kind of ties in with my potting mix ''growing'' method. Becuase I have lots of room I'm growing my own paph mix by planting fast growing ferns into large pots of treated coco/bark/treefern mix. within about one year, the pot is totally root bound in fern roots almost every particle of chc is penetrated with the fern roots. Then its just a of matter taking to it with an axe, washing out all the fines and humus etc and planting your paph! I've tried it on a small scale with good results. It seems all the negative problems with raw CHC are gone by then. Now I have about 60 ferns going. I'll post some pics at some point.


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## ALToronto (May 7, 2013)

What about mosses, ferns and other 'companion plants' on mounts? Do they do any harm?


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## Brabantia (May 9, 2013)

Thank you all for your comments. I learned what is exactly lieverwort. 
I removed some mousses out of the surface potting (not all) of some plants and replaced with a fresh mix. I agree that air circulation in the potting is very important. It is the reason why I cultivate none of my Phragmi. with the pot soaking into a saucer with a water level. I have no Phrag. bessae (which is best to cultivate in a saucer) if I have one I would drill holes on the side wall of the pot.


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## SlipperKing (May 9, 2013)

Everybody is expressing concerns about air movement in the pots when ferns have sprouted. You do realize the largest source of air is when you water? When you pour tons of water onto your pots the action of the water rushing draws huge volumes of air into the pot at the same time. You have no problem with air in the pot if this is how it works when you water but if the water puddles at the top of the pot as soon as you add water...you have a problem. You can have either condition with or without the cute ferns. I'm sure the lady with the dendro and the fern had this issue and didn't realize it.


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## Tom499 (May 9, 2013)

In time bryophytes can create quite a thick carpet over the top of the pot which can inhibit watering, and speed up break down of organic substances in the pot, as well as sponge up a lot of moisture, which isn't great for epiphytes.


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## NYEric (May 9, 2013)

http://www.bing.com/images/search?q...595AC67C0E9773435A2B93EE57C&selectedIndex=125
Like these? :evil:


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## Tom499 (May 9, 2013)

That's different to a pot


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## Stone (May 9, 2013)

SlipperKing said:


> QUOTE] You do realize the largest source of air is when you water?


Actually, diffusion is the main way air gets into media. The larger pores in the medium are in contact with the atmosphere and down to the roots through a maze of pores. As roots and microbes use oxygen, so more is then diffused in. The rate depends entirely on size and number of pores in contact with the atmosphere. Watering has only a minor overall effect on air availability. Consider a tree in the desert that hasn't recieved rain for 10 years.


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## Trithor (May 9, 2013)

I think there is a difference between a parvi in my greenhouse getting watered every three days and a tree in the desert getting rained on every 5 years, water draining through a pot will certainly pull air along with it as well as behind it. That diffusion occures along concentration gradients is also accepted.


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## Stone (May 10, 2013)

Trithor said:


> I think there is a difference between a parvi in my greenhouse getting watered every three days and a tree in the desert getting rained on every 5 years, water draining through a pot will certainly pull air along with it as well as behind it. That diffusion occures along concentration gradients is also accepted.



No difference. The tree will need just as much air as the paph (more or less) If a plant in a pot had to rely on air getting sucked in with watering it would suffocate. The amount of oxygen held in the pores would surley get used in a matter of several hours. Especially by a plant with many roots. Not to mention the billions of aerobic microflora.


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## Brabantia (May 10, 2013)

This discussion on the efficiency of the oxygen penetration in the substrate remembers me the following story. A few years ago I visited a producer of Phalaenopsis here in Belgium. He said to me that one of its two tanks for rainwater storage gave a better growth of its plants than the second tank. He explain me that this is just because he had installed an air blower to inject air in the first tank.


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## NYEric (May 10, 2013)

Even an air diffuser in a tank adds oxygen to a solution so...


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## Rick (May 10, 2013)

I think the amount of gas diffusion in a pot is not influenced greatly by the amount of moss cover or fern root density as a mechanical function of material density (its just not that well sealed).

But you can have CO2 buildup based on plant and bacterial respiration that could go up and down considerably during light/dark phase based on the amount of "biology" going on and the amount of water in the pot.

This would probably be expressed as fluctuations in pH rather than dissolved oxygen (which would probably stay close to saturation unless the mix was really broken down, dripping in water, and sealed top and bottom).

Humans use a lot more oxygen than plants, and I bet you can still breath through a handful of moss. A dust mask is less porous to gasses than a layer of moss, and people don't suffocate in dust masks.


A more useful analogy is sticking a bunch of people into a room. The amount of leaks seems to prevent suffocation from lack of oxygen, but the CO2 concentrations increase enough to measure pH drop in water vapor (including in the lungs).

Water loves to suck up CO2 but not so good at O2. As CO2 goes into unbuffered water it converts to carbolic (carbonic?) acid to lower pH. 


At what point is this bad for plants or humans????


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## ALToronto (May 10, 2013)

Rick, do this experiment: 

Take a small glass with about 2 oz of distilled water, out of a just-opened bottle. Stick a pH meter in it and leave it on. The initial reading should be 6.9-7.1.

Now take a drinking straw, place it in the water and exhale through it. Watch the pH go down. After about 5 minutes of this, it should be down near 6.5. But just like raising pH with aragonite sand, this isn't a linear relationship. Airborne CO2 alone won't take the pH down by more than 1 full point. 

I did a related experiment a while ago when I wanted to measure the pH of my mineral composite material, both untreated and treated with lithium silicate. The test consisted of pouring small puddles of water on the surfaces and taking pH readings with strips (0.5 accuracy). 

Untreated started at a pH of 11.0 and after about 4 hours it reached 10.0. After 8 hours, it still read 10.0. Treated started at 9.0 and levelled out at 8.0. The most surprising finding was that after 8 hours, I still had puddles of water on flat surfaces.


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## Rick (May 11, 2013)

Actually we do this experiment fairly frequently. Human exhalation doesn't have that much CO2.

We use bottled CO2 gas, and use a CO2 monitor to control a solenoid valve. Depending on the buffering content of the water to start with, we can get the pH to drop to about 5.0 in standing water placed in the room. This system is actually made for GH use, but we use it in the tox lab to stabilize the pH of water samples. The toxicity of ammonia and many metals is pH dependent. So as gas balance changes in buffered water samples, the pH will generally rise over the coarse of the test duration.

But I would agree you can't get the pH to drop below ~4.5 no matter how pure and how much CO2 you pump into a room (or bottle of water). Check the pH of a freshly opened bottle of Perrier water, and then aerate it for a few hours and check again.

Not sure if anyone is using the CO2 injection systems for home aquarium systems anymore. But these were popular for aquariums specializing in live plants. These used pH controllers to regulate the CO2 injection. Granted you didn't want to drop the pH lower than 6-6.5 if there were fish in the tank.


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