Is flushing the pot with water necessary?

[fredg]

Now it's getting very very silly so before we descend into farce I'll stop asking the pertinent question. Such a pity no-one could answer it.

 

[tje25]

So my question to you is "silly" and "farce", but you asking us the same question isn't? I'm fairly open minded, so if you disagree with what the people aboves experiances show, then by all means please share proof.
I believe Butch's plants are all the proof I need...plus it just seems logical in my mind.

 

[Whimgrinder]

I'm wondering if this topic is in any way related to the OPs other thread about bong water - "flushing the pot" - so to speak ;-)

 

[Not a Number]

Now it's getting very very silly so before we descend into farce I'll stop asking the pertinent question. Such a pity no-one could answer it.

"absence of evidence is not evidence of absence"

After all we don't want to be wasting time and resources doing things that are unnecessary or of minimal benefit.

You weren't concerned with conserving resources like peat moss in another thread, why is conservation such a concern here?

I have encountered so many facts in this hobby that turned out to be anecdotal misrepresentations that to be answered with a glib oxymoron rings alarm bells. Please publish the results of the trials that prove the fact.

It take it you are referring among other things the root temperatures for Darlingtonia calfornica? I may point out that your observations in this area are merely anecdotal in nature. You had no control groups. You gave very few data points. There was no analysis of the data. Nor did you publish any results in a peer reviewed publication. It's a pity you didn't answer my pertinent questions such as durations temperatures either.

That's a link to "Responses of soil respiration and its temperature/moisture sensitivity to precipitation in three subtropical forests in southern China". I didn't think ps3's plants were growing in a subtropical forest in China. The question was quite simple but it looks like I will have to spell it out.

You may as well ask what relevance growing Darlingtonia californica in a greenhouse in England has to say growing them on a balcony in Singapore. Many basic laws and principals of physics, biology and chemistry (until proven otherwise) work the same in a laboratory as they do in nature and for all intents and purposes are considered universal. Gas exchange across semi-permeable membranes is probably one of them.

 

[Whimgrinder]

After all we don't want to be wasting time and resources doing things that are unnecessary or of minimal benefit.

This is TF we're talking about - where (bad) mythologies and (senseless) anecdotes rule the roost.

 

[fredg]

NaN, perhaps if you read what I actually said in all cases rather than what you think I said you may do a little better.

 

[mato]

Providing oxygen to the roots is always beneficial, Fred. Nepenthes aren't bog plants. This is an absurd thing to argue about, especially when there are so many articles that you can easily google for yourself. Providing you with the burden of proof doesn't lie with us, nor should it for something this basic and heavily tested. I'm not sure if you realize this, but your argument sounds more like an argument against Botany/Physics 101 than it does against poor cultivation advice, which is how you seem to want to frame it. Some people never "flush" their pots, but like Paul Barden, they also tend to grow their plants in net pots that expose the root system to a lot of oxygen. Or, if they're like me, they do neither and watch as their media decays faster than they'd hoped, especially if there isn't a lot of aggregate. It's a useable technique, but I would never tell someone it's the best option. Would it ease your mind to know that the oxygen content of soil is generally the same as that of humid air, which isn't necessarily the same for potted plants because of the lack of soil respiration caused by surrounding vegetation, particularly trees? Basic stuff, Fred. If you don't believe anyone here, audit a class and learn from someone you have more respect for.


Edit: Just curious, are you arguing against flushing the pots or root oxygenation? It seems to have moved towards the latter after you questioned the facts Butch presented, but if you are looking to argue against flushing in general, you could probably move it in another direction. One thing that comes to mind, if people flush their pots too often, they may be depriving their plants of necessary soil nutrients. There's a fine balance between too much and too little nutrients.

 

[fredg]

Now you're forcing me back in.
Mato I believe you have answered the question.
Is it beneficial to frequently flush the medium in terrarium plants?
Some think yes some think no so it must be a matter of opinion. Thank you

 

[RSS]

I would be very careful about removing "Highland Nepenthes" from the theme of this "discussion". Once you open this up to terrarium plants or plants in general it is over quickly.

There are HUNDREDS of published trails/books/experiments from good sources (NASA, commercial growers - who only care about health/growth rate as it equals $$$). Aeroponics, hydroponics, aquaculture and the like are all very well documented and many references give ranges for specific gases in these setups. Depending on what is being grown some are setup with to add oxygen while others add CO2.

They are not doing this because it is an opinion, it is from trial and error over time. You can even watch documentaries on TV about these farms so no reading is required if you prefer, many of the good ones are being done in the UK.

Flushing a pot, will increase airflow into the medium, this is science. Look it up and test it out yourself some of these tests can be a lot of fun. Now if that air is better in quality than what air was in the medium the plant will be better off. But if that new air for whatever reason is worse the plant may suffer. This is where pot type/size/medium/humidity/ect would come into play. Net pots, clay pots, plastic pots would all play a huge factor in the results you would get. Flushing small net pot for instance would have much less of an impact than flushing a large plastic pot. Flushing charcoal is actually a bad thing due to the how charcoal functions in mediums. This is probably the reason for the "myths", you can not forget the 90 other factors of your growing area and just pull a single line out of someones post and reply with "your wrong". Those 90 other factors may very well be why it works just fine for them and not you.

Here is where you have to think, would you flush a bog plant? I'd think not, they would not like that. Few times a year, they might like. Would you flush a rainforest plant during the rainy season, why yes. How about flushing during the dry season? Well no.

As to the original question, since I have had Neps growing for years (seedling to "adult", 10+ years) without being "flushed" or even watered under my growing conditions flushing is just a waste of my time. They get repotted but not flushed. I do however mist them weekly, mainly to keep the dust off . See above thou, your 90 other factors may require flushing.

 

[Est]

Jumping in here a little late, but it seems like there's something to be said for each side of this discussion. Stating that a first principle exists isn't evidence that it has a significant effect in a given case. Nor does absence of a "trial" suggest that a first principle doesn't exist or doesn't have a significant effect. As someone mentioned, TF has been its host to a whole assortment of assertions from coffee grounds to superthrive, from magical colloidal silver (one of my favorites! ) to worries about copper pipes, from aeration to peat tea, and everything between. Some of this stuff been shown to have an effect under conditions X, others are untested old grower's tales that crop up every few years, and others are certifiably crazy.

So when someone makes an assertion about the efficacy of a technique or potting materials or whatever, I think it's fair to ask "have you ever done a comparison?" or "I'm interested in this -- do you have any suggested reading?" This doesn't (necessarily) come from a place of incredulity or disrespect; when I see that someone is trying something new, I'm curious to see how effective it is.

Things that aren't useful in these types of discussions include:

Please publish the results of the trials that prove the fact.

Lets turn this around...show us some trials that prove otherwise.

And any other essentially impossible proposition. Trials, even at the hobby scale are expensive and time-consuming (and kudos to those of you who do them!). Requiring someone to have done a "trial" to address the specific aspect of a technique given conditions X and plants Y and potting medium Z is a bit more than you can ask for. Asking if someone has done a comparison is pretty reasonable. If they have not gone through the trouble of thoroughly testing a first principle, it doesn't really invalidate it. I'm sure I can demand a level of specificity to prove why watering plants works that you won't be able to answer it. Just because someone hasn't spent their life elucidating the finer points of hydrodynamics in the rhizosphere, we can all agree that: watering plants generally keeps them from drying out. I don't need you to have done an isotopic tracer experiment to understand that. Similarly, asking for a negative proof is equally (if not more) pointless.

All this is to say: We're all just curious how effective given horticultural practices are. There's plenty of misinformation in horticulture/agriculture, even the biggest farmers with the biggest profits do some pretty stupid/inefficient things because someone once told them it was a good idea (I'm looking at you, Illinois). So let's all just go ahead and chill out a little. Someone asking for evidence isn't calling anyone a liar. Someone without hard empirical evidence of their own isn't being dishonest.

 

[Whimgrinder]

Some of this stuff been shown to have an effect under conditions X, others are untested old grower's tales that crop up every few years, and others are certifiably crazy.

Bless that nutty Jerry Baker in all his infinite gardening wisdom *cynical laughter*

 

[Av8tor1]

seemed like common sense to me but if it would help...

the occurrence and effects of oxygen depletion has been widely studied in flooded soils
it lowers redox potential, changes the composition of the soil's microbial community, affects the form and mobility of N, Fe and P, increases methane levels, co2 levels, etc etc

(Patrick, 1977, Hook 1984, Faulkner et. al., 1989, Drew 1991, Crawford 1992, etc etc.)

I got 19,000 hits when I used google scholar.

and the fact that water draining through the pot will be replaced with fresh air is simple physics..

but as EST pointed out... I could ask for evidence that black is black in such a way that you couldn't provide it, so what does it matter
Instead of debating why we may not agree, lets just reply to every thread with "prove it" from now on.

 

[fredg]

I have to ask Av8tor. Did you even look at the question I asked?

 

[Av8tor1]

yep,

I had also wondered if you had read my original response, the original poster asked for comments about the claims that flushing the pots increased oxygen levels.
My entire response was in reply to that.

I even quoted the original poster...

then you came back and asked if that was my opinion or if i had done trials...

and I said I felt it was common sense, which i do... and I stopped posting... so yeah, i think so

 

[fredg]

So if I wanted to challenge the physics I would edit all reference to the physics from the quote?

 

[Av8tor1]

if you feel oxygen is not needed in the root zone then please post why you think it doesn't matter, ill read it and consider it
maybe I'm wrong.... but to me that seems like common sense too

 

[dionae]

I can't believe this debate() has gone on for so long. Amusing, to say the least.

 

[Not a Number]

Hydric Soil

Most soils are aerobic. This is important because plant roots respire (that is, they consume oxygen and carbohydrates while releasing carbon dioxide) and there must be sufficient air—especially oxygen—in the soil to support most forms of soil life. Air normally moves through interconnected pores by forces such as changes in atmospheric pressure, the flushing action of rainwater, and by simple diffusion.

In addition to plant roots, most forms of soil microorganisms need oxygen to survive. This is true of the more well-known soil animals as well, such as ants, earthworms and moles. But soils can often become saturated with water due to rainfall and flooding. Gas diffusion in soil slows (some 10,000 times slower) when soil becomes saturated with water because there are no open passageways for air to travel. When oxygen levels become limited, intense competition arises between soil life forms for the remaining oxygen. When this anaerobic environment continues for long periods during the growing season, quite different biological and chemical reactions begin to dominate, compared with aerobic soils. In soils where saturation with water is prolonged and is repeated for many years, unique soil properties usually develop that can be recognized in the field. Soils with these unique properties are called hydric soils, and although they may occupy a relatively small portion of the landscape, they maintain important functions in the environment.[1]

The plants found in hydric soils often have aerenchyma, internal spaces in stems and rhizomes, that allow atmospheric oxygen to be transported to the rooting zone.[2] Hence, many wetlands are dominated by plants with aerenchyma;[3] common examples include cattails, sedges and water-lillies.

There are plenty of studies on the formation of aerenchyma in the roots of plants in response to flooding. Many plants will form the internal spaces in the stems, rhizomes and roots to increase oxygen transport to the roots when placed into anaerobic conditions. Some will just grow shallower roots as the oxygen content is higher towards the surface.

Diffusion is a rather slow process - the amount of time it takes for a substance to diffuse is proportional to the square of the distance traveled. If it takes 1 second for something to diffuse 100 microns in water it will take 100 seconds for 1mm and 10,000 seconds (2.78 hours) to diffuse 1cm. That's why fish flow water over their gills - to clear away CO2 and other waste products and get more oxygen. Water flowing over roots would perform a similar process.

The Anatomical Characteristics of Roots and Plant Response to Soil - S.H.F.W. Justin and W. Armstrong
http://www2.hull.ac.uk/science/PDF/BioSci_48a_Justin_Armstrong_Anatomical.pdf
Lysigenous aerenchyma formation involves non-apoptotic programmed cell death in rice (Oryza sativa L.) roots - Rohit Joshi and Pramod Kumar
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3550533/
Oxygen transport in soil and the vertical distribution of roots - F. J. Cook, J. H. Knight, F. M. Kelliher
http://www.publish.csiro.au/paper/SR06137.htm

If you want to question the relevance of these studies I'll just say they were conducted in the UK, US and Australia on a number of Wetland, intermediate and non-wetland species.

Consider this also
Influence of root zone oxygen stress on potassium and ammonium absorption by Myrobalan plum rootstock - C. J. Rosen, R. M. Carlson

http://link.springer.com/article/10.1007/BF02140041

Summary
Growth chamber experiments were conducted with ‘French’ prune (Prunus domestica L.) scions grafted on Myrobalan 29C (P. cerasifera Ehrh.) rootstocks grown in nutrient solution to characterize K and NH4 uptake before, during, and after anaerobiosis. Conditions of oxygen stress were imposed by removing the source of aeration and bubbling solutions with nitrogen gas.

At solution oxygen concentrations less than 1%, K leaked from plant roots. After 18 h of anaerobic conditions, aeration was restored and K depletion from solution occurred within 2 h. Uptake of K the following day was similar to that before oxygen stress was imposed.

Under similar conditions with solution oxygen concentrations less than 1%, both K and NH4 uptake were inhibited. Potassium leakage from roots was significantly greater than that of NH4. The presence of NH4 had no significant effect on K leakage from roots. Signs of wilting during oxygen stress appeared first on those trees that received NH4. Potassium uptake by rootstocks in the presence of NH4 was inhibited prior to and following anaerobiosis. However, the extent of NH4-induced inhibition of K uptake before anaerobiosis was similar to the K uptake inhibition after anaerobiosis.

 

[fredg]

I never said that getting air into the root zone wasn't a good thing. Flushing isn't the only way to get it there. Top watering will introduce air, so will tray watering when the pot is lifted out, the science will demonstrate that. Not everyone thinks flushing is the way to do it so do they not have common sense? There are other ways of introducing air and there are many different growing conditions to take into account
If I may point you back to my question there was an option to say it was your opinion that flooding may be beneficial rather than the definite will be, as implied by your "common sense" reply. You chose not to go that route. It is my opinion that the former is a more honest and correct response.

 

[tje25]

I don't think anyone's talked about "flooding", just "flushing"...but I may have missed something.