Water

[Stone]

I realize watering is probably furthest from the minds of the Northeners but ''watering season'' is not that far away.

Anyway, at our club meeting the other night it was mentioned by in passing that there is a growing trend amongst some paph growers here to sit their plants in water over the growing season and i'm also experimenting with this this year. It got me thinking: If so many of these plants do well with wet feet, then maybe the method of letting them dry between waterings is misguided? If they enjoy so much water without their roots rotting then its obvoiusly not the water causing the problem but possibly an imbalance in the bacterial population in the mix...insufficient numbers of supressive bacteria which feed on the pathogens as occurs in a natural ecosysyem.

I had a look through an old orchid book (1951) to find the following lines. "
'' So far as comopst is concerned, the Cypripediums (paphs) are adaptable to numerous materials. They can be potted exclusively in tan-bark (spent bark from tanneries), good Todea fibre (like osmunda), course leafmold and cow manure and various native barks stripped from dead trees and leafmold and humus gathered in the forest''

Many of these materials are now known to supress pathogens for up to 2 years where as pine bark for only 6 months or so!

With regard to watering, the 1951 advice was: December (June in the north)
'' It is practically impossible to overwater the great majority of orchids this month, so give AT LEAST! two copious waterings EACH day, one in the morning and the other at nightfall, or at some time about sunset when the sun has lost the intensity of its heat''
''Wooden reseptacles require very close attention and plants mounted on fern fibre or other quickly drying material such as a block of wood need constant dipping''....''Make the plants grow by regularly watering them''

All this water and such a water retentive mix and no root rot!

When you think about it, during monsoonal downpours, the plants can be saturated for days at a time and thrive! on it. So theoretically and in the right environment ( warm and windy) you should be able to water every single day or more and get the ''wild vigour'' that we all want. maybe we are paying too much attention to feeding techniques and not enough to setting up an environment where we can ''really'' water the plants as they have evolved to thrive on.

Just a thought.
Mike

 

[ehanes7612]

might have something to do with the oxygen content in the water....standing water would have less oxygen content as bacteria growing and algae dying off ..moving water is going to have less growth in it so more oxygen and less bacteria therefore less rot..i make my mixes so i dont have to water so often ..watering twice a day or even once a day wouldnt be practical..but even in those kinds of mixes..really hot summer days require watering everyday

 

[dodidoki]

There is a thread in ST about in situ pics of volonteanum. These plants are standing always in water. Rot is caused as you mentioned not by water I think but by building up of salts, bacteria and lack of oxigen. In nature roots are constantly washed around by fresh rainwater full of solved O2 furthermore much of rainwater washed out pathogenes mechanically.
I thought about daily waterings with fresh RO water, sometimes low TDS K-lite....

 

[wjs2nd]

I've started, though out the entire year, watering more. I think I was letting things get a little to dry. I have noticed and believe that the pots drying to much were a problem (unhappy roots). I have a few pots that hold moister and they have much happier roots.

 

[Ray]

OK, so that's semi-hydroponics, only using organic media that will decompose over time.

I am absolutely convinced that the issue is suffocation, not wetness. All of my slippers are in S/H culture (using LECA), stay wet 24/7, and thrive. My longest-term plant grown that way is a Paph Maudiae-type, and it's been constantly wet for 18 years.

 

[The Orchid Boy]

OK, so that's semi-hydroponics, only using organic media that will decompose over time.

I am absolutely convinced that the issue is suffocation, not wetness. All of my slippers are in S/H culture (using LECA), stay wet 24/7, and thrive. My longest-term plant grown that way is a Paph Maudiae-type, and it's been constantly wet for 18 years.

I'm no expert but, what Ray is saying makes sense. If paphs can live in S/H and be constantly moist/wet in LECA, they could do the same with organic media, as long as there is lots of air available to the roots. The air to water ratio would have to be correct.

 

[gonewild]

I said a billion times here.... Orchids grow best if the stay wet. They like their leaves wet they like their roots wet.

You need to have the correct light, temperature and air movement and use a media that does not rot easily and then keeping the plants wet is correct. This requires a dedicated growing area like a greenhouse or grow room, not well adapted to a shelf or windowsill.

If I have the above environmental conditions set up correctly then I water everyday with nutrient solution. I run intermittent mist that keeps the foliage wet and the media surface wet. Mist comes on as the day starts and ends in time so that the foliage is dry by the time the light goes out.

If you have absolutely perfect environmental control the wet foliage at night is not a problem but that means strong air movement and warm temperature which we really don't like to provide so just dry off plants at night.

My last orchid collection I had in Peru was in a lath house and I ran a mist system in it 24/7. Every hour the mist came on for one minute. Never a rotted plant.

Two major factors to have success with the wet method are use a media that does not rot and use a nutrient solution to feed the plants. Leca is a perfect major component for the media, just mix in some form of organic material to buffer it. Orchid roots need something stable to attach to and decaying bark is not stable where leca is. When you use the inorganic media you need to supply more nutrients.

 

[eggshells]

What would be the best temperature for watering? As we know, cold water has more oxygen than warm water but what temp is too cold?

 

[gonewild]

What would be the best temperature for watering? As we know, cold water has more oxygen than warm water but what temp is too cold?

The best temperature for water is the same as the leaf temperature.

 

[gonewild]

I think I tried to argue the benefits of oxygenated water a few months ago in a thread here on ST.
As I recall I might have lost the argument? :sob:

 

[NYEric]

I grow my plants fairly wet. the only problems I have had has been with rotted media and if water sits in the crowns of the leaves.

 

[Rick]

Isn't this just resurrecting the TDS monitoring thread I started last summer?

It's not the large amount of water or suffocation that causes root rot but the accumulation of salt by frequent small amounts of water (usually with fertilizer) evaporating in the mix. Salts stay in and build to higher/higher levels with each abreviated watering.

The hotter/dryer it gets the faster this happens.

Also not all "salts" are created equal. Some (like potassium and chloride) are more bioreactive than calcium and sulfate.

Regardless of issues with physiological salt "toxicity", the higher the TDS in the potting mix generates an osmotic gradient making it harder to pull water uphill into the plant during hot/dry times.

 

[newbud]

Thanks Rick and all. Good stuff.

 

[phraggy]

I water my phrags 24/7 on a drip system with cold water. I use NZ sphagnum mixed with large American sponge rock and only feed twice per year with blood and bone.The roots when first put in this method rot off but are eventually replaced by,what can only be described as thick white hairy rock hard roots.

Ed

 

[gonewild]

The roots when first put in this method rot off but are eventually replaced by,what can only be described as thick white hairy rock hard roots.

Ed

Is that good?
oke:

 

[Ray]

t's not the large amount of water or suffocation that causes root rot but the accumulation of salt by frequent small amounts of water (usually with fertilizer) evaporating in the mix.

Not always.

Put a plant in very compact, fresh sphagnum and keep it saturated with pure water. No salts, but the roots will die from suffocation.

 

[gonewild]

Not always.

Put a plant in very compact, fresh sphagnum and keep it saturated with pure water. No salts, but the roots will die from suffocation.

It might not be either salts or suffocation. It may just be the plant disposing of roots that no longer function in their environment. If a root refuses to pay it's rent the leaves kick it out of the house.

(Now how am I going to argue this statement?) :evil:

 

[Stone]

Isn't this just resurrecting the TDS monitoring thread I started last summer?

It's not the large amount of water or suffocation that causes root rot but the accumulation of salt by frequent small amounts of water (usually with fertilizer) evaporating in the mix. Salts stay in and build to higher/higher levels with each abreviated watering.

The hotter/dryer it gets the faster this happens.

Also not all "salts" are created equal. Some (like potassium and chloride) are more bioreactive than calcium and sulfate.

Regardless of issues with physiological salt "toxicity", the higher the TDS in the potting mix generates an osmotic gradient making it harder to pull water uphill into the plant during hot/dry times.

All true but the other important point is the supressiveness of certain materials. I had another look at the info in my book. It states that some materials can give 3 years of complete freedom from parasitic fungi attack when added to mixes in as small a quantity as 10%. Some of these include some but not all composted and aged eucalypt barks and other hardwood barks. The suppressiveness of
pine bark is exausted in about 2 months. Thats a huge difference! I think I read some data done in the US on the web but I don't remember the tree sp. that produced similar results. ( a quick search should find it ) The suppression is directly related to the on-going decomposition and the maturity of the material. Apparently the older the better. But any old (several years) organic material (what paphs grow in) will give some measure of control. Those with access to an old growth forest, could gather some old humus from under the leaf litter, screen out the fines and add 10% of that to your mix?
Ok here is some data on this subject
http://www.globalsciencebooks.info/JournalsSup/images/Sample/DSDP_5(SI2)1-11o.pdf

 

[Stone]

Not always.

Put a plant in very compact, fresh sphagnum and keep it saturated with pure water. No salts, but the roots will die from suffocation.

I agree. Thats why I never use sphag in the mix and why I melt slits in the sides of the pot. Otherwize the only access to air is from the top and bottom of the container and if its in water, only the top.

 

[Stone]

I said a billion times here.... Orchids grow best if the stay wet.

A billion is just not enough!