The 'water twice' approach to watering

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richgarrison

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I've heard the 'water twice' approach to watering a multitude of times from many people, some of which i tend to trust implicitly. In all cases the speaker discussed authoritatively the value of watering twice in getting a thorough watering of the plant. and for me that aspect of the discussion has always been proven by experience.

The part that appears to be less 'authoritative' is the procedure of which watering includes the fertilizer (or maybe both). I've tended to buy into the 'gut' feeling that fertilizing first made sense since in nature when it rains that first solution hitting the roots will have the most nutrients. (heard this first from @Ray )...

In some random reading i came across a reprint of an article published in Orchid Digest (Orchid Digest, Jan., Feb., Mar. 2015) written by Carol Siegel entitled 'The Secret Life of Orchid Roots' where she references research by Zotz and Winkler where this topic was studied... Since i haven't actually tracked the reference down and read it, i won't say what it concludes, but Carols article states "Gerhard Zota (mis-spelled?) and Uwe Winkler did a series of experiments showing that velamen allows the orchid to capture and retain the first solutions arriving in a rainstorm, which have the most nutrients."

so.... i don't know about you, but i can certainly sleep better at night now that this debate appears resolved..

:)

Zotz, Gerhard and Uwe Winkler. “Aerial Roots of Epiphytic Orchid: The Velamen Radicum and Its Role in Water and Nutrient Uptake", Oecologia, 141 2013:733-741
 

Ozpaph

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i fertilize first, then later water. Seems logical when you look at exposed vanda and phallie roots - after wetting them, they are 'saturated'.
 

Ray

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Zotz and Winkler compared the velamen of several different genera of orchids - some thick, some thin - and concluded the existence of a cation trapping ability.

To me, it makes sense, in light of the natural dynamics of living in a forest, where rains wash the nutrients out of the canopy almost instantaneously, followed by a pure water deluge thereafter.

Alan Koch (Gold Country Orchids) told me it wasn’t true, but did not back the statement up, so I’m still going with it.
 

richgarrison

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Zotz and Winkler compared the velamen of several different genera of….

Alan Koch (Gold Country Orchids) told me it wasn’t true, but did not back the statement up, so I’m still going with it.
He was one of the ones I had in that ‘trust implicitly’ category….

I’m sticking with the fert first approach. Hasn’t caused any Ill effects yet. :)
 
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For many years now. I have always flushed with fresh clean rainwater first, to remove all old solids. Then, I water a second time with my fertilizer solutions. This always seems to work well for me!
George
 

cnycharles

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If your plants are over dry, and you are going to feed with something really strong, it may be better to hydrate to a better level and then at some point give a feed. Also if you are a heavy feeder and you let your plants get really dry (like cattleyas possibly) then you can get built up dried up salts on the surface, and it may help to loosen them up with water first and flush, then later feed. But if you do cyclical watering (feed one time and water a few days later) and don’t let things get too dry in between then that could accomplish feeding and flushing. In nature probably things don’t get as dry as in culture or have heavy fertilizer sitting on it. If you feed lightly and never really let things get dry, then the jungle example could be accurate

So the answer is ‘it depends’ :D
 

Sky7Bear

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Thanks, Ray, for your input. I have always watered first and then fertilized, but that doesn't mean it's right. However, I think you have noted elsewhere that the game is quite different for those of us growing in semi-hydro, which means the roots are always wet and hydrated. This would be true for several other genera which don't like to dry out at all. I'd put Phrags, Miltoniopsis, Masdevallia and Disa in that category, even when grown in organic media. Mounted, of course, always get dry velamen, but I'd say for me almost nothing else does. So I go with a fairly weak solution of fertilizer as the last stage of watering after 3 rounds of pure RO water to flush out any minerals that remain in the container.

Indeed, I don't fertilize at all from Halloween until about now, just before Imbolc n the Celtic calendar (halfway between the winter solstice in the northern hemisphere and the spring equinox, also known as Candlemas, St. Bridgid's Day or Groundhog Day). This gives the medium a chance to be thoroughly flushed when there is little growth, but I can already see new growth right on schedule, about MLK Day. I grow almost nothing in pots that dries out in between, though I have a friend who does very well with Phals in large Orchiata that he makes sure is dry before re-watering (would probably work well with Catts as well). He thinks it's about water, I think it's more about air, but it doesn't matter as his roots are adapted to that growing condition.
 

Ray

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Personally, I think the only things “wrong” with watering first, then feeding, are doubling the amount of time needed for the task, and potentially wasting fertilizer more than we already do, considering the large “pour through” of orchid media - neither of which is a big deal.

@Sky7Bear - while I think that no food for months may lead to better leaching of mineral residues from the medium, I suspect it’s not as thorough as assumed.

Minerals are pulled into the interior of media as the solvent evaporates, outside-in, concentrating as it does so. It takes a relatively long time for water to penetrate into the subsurface cells, redissolve the solids, then carry them back to the surface to be carried away, so the extraction by the brief flow of plain water isn’t all that efficient.

I had someone tell me they tested the EC of the drainage water an “knew” they had completely cleaned out the mineral buildup because the EC was essentially unchanged, but when they took that medium and let it sit in RO water overnight, the EC was a lot higher than they realized.
 

Sky7Bear

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Well, Ray, I water first so as to leach out the salts, but then we don't really know that it works! LOL. If I'd thought of it a couple of weeks ago before starting fertilizer again, I might have tried some experiments. Perhaps I still have some leca outside (that's also been rained on!) that I can soak and measure with just to see how much it invades the interior of the leca "ball." I do reuse leca, and so I would expect to leach it in any case. Let's see what still comes out. As far as only a weekly basis, perhaps a good point. I do like to make sure that the plants are thoroughly watered and overwatering in S/H is one way to make sure it happens, and perhaps more air gets into the pot. Always more questions than answers. And yes, it does take more time, probably for me about 15 minutes. Maybe I should return to one water only watering with one only fertilizer only. Of course, the reservoir is never empty for me, and so who knows how much fertilizer even gets into it. AND, the plants seem happy, so perhaps leave well enough alone, especially now that days are getting longer. So, I will measure what I have with plants that have died. LOL.
 
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