Water

[gonewild]

The slow application of rainfall does not really compare to the rapid application of irrigation in a potted plant. Filling a 4 inch deep pot with water and letting it drain out quickly is not the same effective soil moisture as 4 inches of rain over a 24 hour period.

When I reference my continual mist system the "rainfall" measure from the mist is 1 cm per day. That is the standing measure of water (pure) that flows through the pot. This moisture keeps the foliage wet but also flushed through the media.

Then on top of this amount of water I water the pots with nutrient solution.
You can't use the measure of water I apply with the nutrient solution to add to the "annual" rainfall comparison because it is basically instant monsoon and then in an instant it is "gone" as far as total water volume.

 

[Stone]

for the example above where you've dunked your plant and say that it's received 70mm of water; it doesn't really compare to the statistics in the wild. in a pot, roots aren't growing in the maximal concentration area for receiving water, and in the wild they are. a tiny bit of water (in the wild) will have more contact as a plant will be growing right where the right water is, and for epiphytic ones the roots are in constant contact with the substrate and where the water will be. also runoff condensation is not accounted for in the rainfall records for an area.

I obviously didnt make myself clear (my bad!) But thats what I was getting at. Even though the plants are actually getting more water in captivity than rainfall in the habitat, its probably not enough due to the retricted volume of the pot so we need to give much more to make up for the slow and sometimes constant rainfall they would recieve in the habitat and as you mentioned all the runoff. Also, if our water is low in nutrients, (which most are) we need to fertilize at higher concentrations or, preferably, more often at lower rates to make up for all the leaching. The Japanese have a saying when it comes to potted plants: Open mix + lots of water + lots of (meaning consistant) food = better plants.
If only someone would maufacture a slow release fertilizer with ALL nutrients (not blends) in a larger pill-sized form it would manner from heaven! Just throw some on at the start of the season and then water as much as you like. No more mixing! no more watering cans, no more dipping....

 

[Stone]

The slow application of rainfall does not really compare to the rapid application of irrigation in a potted plant. Filling a 4 inch deep pot with water and letting it drain out quickly is not the same effective soil moisture as 4 inches of rain over a 24 hour period.

When I reference my continual mist system the "rainfall" measure from the mist is 1 cm per day. That is the standing measure of water (pure) that flows through the pot. This moisture keeps the foliage wet but also flushed through the media.

Then on top of this amount of water I water the pots with nutrient solution.
You can't use the measure of water I apply with the nutrient solution to add to the "annual" rainfall comparison because it is basically instant monsoon and then in an instant it is "gone" as far as total water volume.

Agreed! Thats why we can't use rainfall figures as a guide to the volume of water we need to apply to the pots or the greenhouse. But we can use the total rainfall data to establish how much water the plant likes (if you follow)

 

[Rick]

Agreed! Thats why we can't use rainfall figures as a guide to the volume of water we need to apply to the pots or the greenhouse. But we can use the total rainfall data to establish how much water the plant likes (if you follow)

How do you get "more" water than standing water in a tray?

If it's there 24/7 you can't get "more" into that tray.

Or did we shift back to watering open pots without sumps?

 

[Stone]

How do you get "more" water than standing water in a tray?

If it's there 24/7 you can't get "more" into that tray.

Or did we shift back to watering open pots without sumps?

Both! The plants with sumps get watered just as much as everything else from overhead. The only real difference is that they have constantly wet feet. I'm still feeling my way through this but I put a seedling roth in a water tray a week ago and it already has a root going for an underwater swim. EC of the water is about 0.6 dS/m but this goes up and down a lot. It has osmocote, gypsum, organic pelets and liquid feed now and then but not too much of any.

 

[Rick]

Both! The plants with sumps get watered just as much as everything else from overhead. The only real difference is that they have constantly wet feet. I'm still feeling my way through this but I put a seedling roth in a water tray a week ago and it already has a root going for an underwater swim. EC of the water is about 0.6 dS/m but this goes up and down a lot. It has osmocote, gypsum, organic pelets and liquid feed now and then but not too much of any.

I'm not surprised. I think a lot of paphs could stand a lot more water than we offer.

Can you get a hardness measure of your tray water?

 

[gonewild]

How do you get "more" water than standing water in a tray?

If it's there 24/7 you can't get "more" into that tray.

Or did we shift back to watering open pots without sumps?

Standing water in a tray does not compare to water moving down through the media, either in a pot or in nature.

Standing water in a tray does not address the very (very) important media surface. Letting the surface dry out can delay new rood development. This is especially true with Paphs and Phrags where most new roots start at or above the media level. It may not be "water" on the surface that makes a difference but rather the water dilutes the "salts" that accumulate by evaporation every time the surface dries and moves the salts down and out.

 

[phraggy]

I haven't seen anything in the posts that contradict my growing of phrags and paphs indeed all the later posts seem to say that this method is correct!!
I'm thinking that I am very lucky with my water quality--very soft, slightly acid 6.8 .

Ed

 

[Rick]

Standing water in a tray does not compare to water moving down through the media, either in a pot or in nature.

Standing water in a tray does not address the very (very) important media surface. Letting the surface dry out can delay new rood development. This is especially true with Paphs and Phrags where most new roots start at or above the media level. It may not be "water" on the surface that makes a difference but rather the water dilutes the "salts" that accumulate by evaporation every time the surface dries and moves the salts down and out.

Generally I agree. It's different for sure. Gravity (water flows downhill) versus capillary action (water wicking in any direction including uphill). But on the side of a tree don't both things happen too?

Plants in pots sitting in trays of water don't have to send roots into the sump to get the water since it will generally travel up to them via wicking action. The fact that orchids are willing to send roots into standing water is more an indication of how wet they can get and still not rot (which I thought was the premise of this thread to start with).

Capillary action is a physical process, so the accumulation of salts on roots or the potting mix surfaces is not mandatory. However, since this is driven partially by evaporation, its easy to accumulate salts on wicking materials. So it helps to keep the sump water low in salts to start with, and still periodically flush out the pot.

I have a good size pot of Phrag caricinum (posted pics a couple years in a row) that is in some kind of clay ball media, and the whole thing sits in a tray of water. For probably at least a couple of years, I used dilute well water with EC about 80uS/cm, but occasionally the straight well water with EC 600. Fertilizing weekly. I used to just let the tray get sucked up by evaporation or plant transpiration and then just top up. Well when I finally got my EC meter, the tray water was well over 1000us. It was probably way higher, but I can't remember now). Anyway, I've been on a heavy duty flush and dump with this pot for months, and it seems to have stabilized at somewhere between 250-350 us/cm. And now it also is pushing some roots out the bottom.

Anyway yes its easy to get out of hand with the tray system if you don't check EC fairly regularly and flush the system periodically. But one advantage, is that you have pool of water in salt equilibrium with the potting mix, so its easy to get a reading whenever you want instead of messing with pour through rates and stuff.

 

[gonewild]

Generally I agree. It's different for sure. Gravity (water flows downhill) versus capillary action (water wicking in any direction including uphill). But on the side of a tree don't both things happen too?

Ummm? on the side of a tree I don't think upward wicking is as prevalent as downward flow. OK ? On the side of a tree does water have the oppertunity to wick upwards? How is the lower part of the tree wetter than the upper. (upper being above the orchid and lower below).

Plants in pots sitting in trays of water don't have to send roots into the sump to get the water since it will generally travel up to them via wicking action. The fact that orchids are willing to send roots into standing water is more an indication of how wet they can get and still not rot

Absolutely agree I just am saying that even though the plants have roots growing in the bottom water the surface still needs to have a significant amount of water added to have downward flow to constantly replenish the bottom water.

(which I thought was the premise of this thread to start with).

I don't remember what the premise was! Do we have to have a premise? I hate rules about water!

Capillary action is a physical process, so the accumulation of salts on roots or the potting mix surfaces is not mandatory. However, since this is driven partially by evaporation, its easy to accumulate salts on wicking materials. So it helps to keep the sump water low in salts to start with, and still periodically flush out the pot.

My focus in my statement was on the surface salts caused by lack of incoming water. I'm thinking of watering applications that mimic natural conditions and wicking upwards is not really natural in most orchid environments. or are they?

I have a good size pot of Phrag caricinum (posted pics a couple years in a row) that is in some kind of clay ball media, and the whole thing sits in a tray of water. For probably at least a couple of years, I used dilute well water with EC about 80uS/cm, but occasionally the straight well water with EC 600. Fertilizing weekly. I used to just let the tray get sucked up by evaporation or plant transpiration and then just top up. Well when I finally got my EC meter, the tray water was well over 1000us. It was probably way higher, but I can't remember now). Anyway, I've been on a heavy duty flush and dump with this pot for months, and it seems to have stabilized at somewhere between 250-350 us/cm. And now it also is pushing some roots out the bottom.

Exactly my point. water needs to move down from the top frequently, like in constantly.

Anyway yes its easy to get out of hand with the tray system if you don't check EC fairly regularly and flush the system periodically. But one advantage, is that you have pool of water in salt equilibrium with the potting mix, so its easy to get a reading whenever you want instead of messing with pour through rates and stuff.

Yes agreed. And if you can manage to keep a tiny amount of moisture on the surface at all times you will see an additional improvement in root growth.

I did an experiment with a bunch of kovachi seedlings growing with pots sitting in an inch of water(the same tray and nutrients). Half the plants got mist and half did not. The plants without mist grew mostly roots that went down and into the water. The plants with mist grew roots equally in the water and just under and in the surface moss. The plants with roots growing in the surface moss grew bigger and produced more new growths faster.

 

[Rick]

My focus in my statement was on the surface salts caused by lack of incoming water. I'm thinking of watering applications that mimic natural conditions and wicking upwards is not really natural in most orchid environments. or are they?

I would say that yes capillary action happens in the wild as well as gravity. The both rules of physics. However the relative degree to which each happens in their respective environments/microhabitats varies dramatically. As long as its raining, gravity predominates. When it stops raining wicking is all you have.

That's why I don't look at this thread as a new different way of growing orchids as opposed to tweaking a management system to adapt to a set of personal growing conditions.

 

[Stone]

Can you get a hardness measure of your tray water?

Don't have a clue but there must be plenty of Ca in it. ( but not much carbonate I would guess) I did a little experiment with the Rock Gypsum. I put a few granules into one of those little fert baskets with a spike and put it onto a basket which gets watered most days. The particles were about 3 to 4mm. They were completely disolved away in 4 months. Or at least disolved small enough to fall through the mesh of about 1mm.

 

[Rick]

Don't have a clue but there must be plenty of Ca in it. ( but not much carbonate I would guess)

Although Hardness is usually expressed in CaCO3 equivalents, it's just the measure of calcium and magnesium concentration. So the carbonate concentration is not relevant.

Not sure why chemists do this, but the methodology used to determine hardness has nothing to do with any anions (carbonate, chloride, or sulfate), and the hardness "answer" is a back calculation that just assumes a carbonate ion presence (as kind of an industry standard). So a solution of 100mg/L Ca from CaCL2, CaSO4, or CaCO3 all have the same hardness value (248 mg/L as CaCO3)

So you can calculate the calcium and magnesium concentration in solution if you know the hardness value (and the simple equation). And at least one type of hardness test is very cheap and easy to conduct (possibly available from an aquarium store).

 

[Rick]

http://courses.missouristate.edu/alexanderwait/notes/lecture notes/lecture 11.htm

I've been thinking about this one for a while, but as a question related to the culture aspects of watering.

How does ambient humidity level effect uptake and requirements of fertilizer salts?

One of my earliest "epiphany" moments in orchid culture, was that they need a high humidity environment (independent of watering rates and methods).

However, I've been able to induce what appears to be symptoms of nutrient deficiency in orchids kept in low humidity conditions (like in my house/windowsills) getting fed at the same rate as those in my high humidity GH.

Another consideration is the amount of light energy required to move nutrients around in a plant. Are the same dry/low light conditions often found for indoor culture conditions able to cause symptoms of nutrient deficiency?

 

[gonewild]

http://courses.missouristate.edu/alexanderwait/notes/lecture notes/lecture 11.htm

I've been thinking about this one for a while, but as a question related to the culture aspects of watering.

How does ambient humidity level effect uptake and requirements of fertilizer salts?

One of my earliest "epiphany" moments in orchid culture, was that they need a high humidity environment (independent of watering rates and methods).

However, I've been able to induce what appears to be symptoms of nutrient deficiency in orchids kept in low humidity conditions (like in my house/windowsills) getting fed at the same rate as those in my high humidity GH.

Another consideration is the amount of light energy required to move nutrients around in a plant. Are the same dry/low light conditions often found for indoor culture conditions able to cause symptoms of nutrient deficiency?

I'm a little unsure by what you wrote.
You made a "however" statement that has me a little confused, can you clarify if you might have left out a word? I want to make sure I understand your point.

I say once again... orchids grow better with a lot of light and a lot of moisture on the foliage and media surface which comes with higher humidity.
In low light their pumps run slow and in low moisture conditions there is nothing to pump.

 

[Rick]

I say once again... orchids grow better with a lot of light and a lot of moisture on the foliage and media surface which comes with higher humidity.
In low light their pumps run slow and in low moisture conditions there is nothing to pump.

Yup. And if the sump water is high in TDS then the orchids have to pull evaporative losses against an osmotic gradient.

Also the movement of resources through the phloem is an energy requiring process (eating up the sugars the plants are making through photosynthesis).

We've all come up with are zillion ways to skin the same cat. If we are debating what the best way is, I'd say the closest way to mimic nature is the best (i.e frequent rain with very dilute nutrients and high humidity), but that's not to say we can't make other ways work as long as we understand what are the factors that we are compensating for. If that ends up in a labor saving then great. I would also expect a critical review on performance outcomes. Is the plant really bigger/better by the new method, or is it just meeting an already reduced standard that we are satisfied with?

 

[Rick]

I'm a little unsure by what you wrote.
You made a "however" statement that has me a little confused, can you clarify if you might have left out a word? I want to make sure I understand your point.

Basically, some orchids I have in low light/low humidity situations are showing symptoms of "malnourishment" although they are getting fed the same rate as plants in high humidity/light conditions fed at the same rate (that are doing great).

I think we've seen this for some of Mutants and Eric M's plants kept indoors under lights/windowsills with less than optimal humidity.

I don't know if SH will work better under these situations or not. Can the plant beat out a humidity deficit by constant wet feet immersion? I attached that link to see if we can figure out what the plants are up against in low humidity/light situations with regard to energy and water balance. At the beginning of this thread, the premiss to consider was "wet feet in and of itself does not cause root rot". Which I tend to agree with, especially with what I've been experiencing with low K low TDS management.

The thread evolved into another debate on what is the best way to water plants.

Now its pretty obvious that ChrisFl is getting good results with delicate cool growing species with a very sophisticated computer controlled, low nutrient constant rain machine. And Mike is getting some good results with a different group of species in a low tech tray under plant SH method.

So the thread is really to find out why either case works rather than figure out which is better.

 

[Rick]

For yet another perspective:

Plants are generally 80-90% water, and 5 or so % carbon.

The NPK.......only acount for about 3 or so % of the total weight of the plant.

So what plants really "feed on" is water and co2 (to make sugars and celulose).

NPK.... is just to run the machinery of cell metabolism and some cell wall structural integrity.

So you could make the analogy that the NPK..... is really like taking vitamens rather than really eating a meal. Somewhere in our thinking we equated "fertilizer nutrients" as food, and started giving out vitamens as the main "meal" rather than CO2 and water.

 

[gonewild]

For yet another perspective:

Plants are generally 80-90% water, and 5 or so % carbon.

The NPK.......only acount for about 3 or so % of the total weight of the plant.

So what plants really "feed on" is water and co2 (to make sugars and celulose).

NPK.... is just to run the machinery of cell metabolism and some cell wall structural integrity.

So you could make the analogy that the NPK..... is really like taking vitamens rather than really eating a meal. Somewhere in our thinking we equated "fertilizer nutrients" as food, and started giving out vitamens as the main "meal" rather than CO2 and water.

That sounds like something I would say to start an argument.
:evil:

 

[Ray]

The only thing I take umbrage to is the spelling of "vitamin".