Watering/Feeding Technique

[Ray]

Originally Posted by thefish1337

I suspect that watering first doesn't really "hurt" because the roots themselves have a number of mechanisms to pull out charged ions from solution so as long as you soaked your plant sufficiently after pre-wetting I doubt it would hurt much other than waste water and time.

I just think that pre-wetting reduces the uptake, and as I’m talking very low fertilizer concentrations, why would I want to limit it further?

Fill a tub with water and add food coloring. Dunk a sponge in it, then squeeze the absorbed liquid into a glass. Take another sponge and dunk it in plain water. Then, without squeezing it, dunk it in the same tinted water, then squeeze its contents into a glass. Which glass will contain the more tinted water?

[Clawhammer]

Originally Posted by Ray

I just think that pre-wetting reduces the uptake, and as I’m talking very low fertilizer concentrations, why would I want to limit it further?

Fill a tub with water and add food coloring. Dunk a sponge in it, then squeeze the absorbed liquid into a glass. Take another sponge and dunk it in plain water. Then, without squeezing it, dunk it in the same tinted water, then squeeze its contents into a glass. Which glass will contain the more tinted water?

I am completely aligned to your logic Ray in terms of nutrient uptake.

Let me ask you this though... When I water my orchids that I keep in clear pots once, unless I dunk the pot completely or use a full on hose, I see parts of bark that don't get wet because they aren't wetted by the water as it flowed through the pot utilizing the path of least resistance. If I come back and water a second time after letting the first dose absorb into the bark a little, I notice the water spreads out more evenly and covers all the bark. This observation makes me worry I am not fully wetting the roots with one pass. I also have noted that I have to water more frequently if I only go with one pass. I know when I water my vandas a second pass is really helpful in getting the roots fully wetted.

Any thoughts from your experience on hydration efficacy of one pass versus two passes?

[DirtyCoconuts]

Claw- i think you are correct and it is better than nothing. ideal is to get the fert on the roots with the first bit of moisture...if you cannot do that on the first pass ( also due to the medium absorbing some water , once it is wet, the water can flow past it to the lower roots)
do the best you can and then come back and spray them again..while the roots that already got wet will not necessarily uptake more of the fertilizer, the roots that did not get wet with the first pass will be getting their initial wetting and will get the max uptake...in theory

[Ray]

Clawhammer - I think you’ll find that issue to be less of a problem if you don’t let the medium dry out completely between waterings (which also has the benefit of minimizing mineral buildup). Flooding the pots more rapidly and with a greater volume can also help.

When I was still working, watering a thousand orchids at 5 a.m. before going to work needed to be a one-pass thing - no opportunity to go back and do it again. Get out the fire hose!

[thefish1337]

Originally Posted by Ray

I just think that pre-wetting reduces the uptake, and as I’m talking very low fertilizer concentrations, why would I want to limit it further?

Fill a tub with water and add food coloring. Dunk a sponge in it, then squeeze the absorbed liquid into a glass. Take another sponge and dunk it in plain water. Then, without squeezing it, dunk it in the same tinted water, then squeeze its contents into a glass. Which glass will contain the more tinted water?

i'm not disagreeing with you but I think the differences we're talking about is a matter of efficiency and splitting hairs for the vast majority of orchid growers. i personally fertigate every watering.

prewetting isn't ideal but its not a deal breaker- the velamen is more than a sponge. its a sponge that has structures and biochemistry that can hold onto charged ions. your analogy would be more apt if the sponge you put in the water had an anion/cation exchange resin embedded in it. yes though purely diffusion the pre-dunked sponge would take up less dye but if it were more analogous to orchids the sponge would have a passive mechanism that hold onto the dye. given enough time for diffusion + active capture of ions will eventually reach something close to if you had just fertigated initially.

maybe if you were committed to feeding your orchid treetrunk rain leachates it would but as far as I know most orchid hobbyists are feeding complete nutrients and even in a lower ppm feeding regime the orchids should never been in a state of want for nutrients. does it matter if your feeding is 5-10% less efficient? the only case that MIGHT matter is if you're really trying to dial in the absolute minimum fertilizer to apply.

[DirtyCoconuts]

or a LOT of orchids.

if you were to be paying to fertilize 1000 orchids you would want to not waste a drop.

i think that is where the significance of 5-10% comes in


i agree, for me, i don't think it makes a difference