Question on pH and KH.

[CharlesD]

Over my 50 plus years of growing..my water source has varied from RO to various water supplies depending on location and municipal water supply. Currently being in Middle Tennessee in a small community that the municipal has a couple taps on two different creeks…after chatting with them…found they were using one primarily. I thought it was time to have my water tested again. Sent a sample to Peter’s testing lab. I promptly received a result…and called to discuss the results and my desires as per water quality. My PH is a bit above 7, was concerned about adjusting PH. What was recommended was to alternate between two different Jacks formulas. After one year….very pleased with the results. For my money….the water test helped a lot.

I agree! My water was really good when I tested but knowing that I need to supplement micros more than is provided by my regular fertilizer made a huge difference

 

[CharlesD]

I have also evolved to the position that I folks worry too much about keeping the TDS low, or maybe it’s an understanding of what “low TDS” is.

First, be aware I’m speaking of the actual fertilizer concentration, not a reading on a crap TDS meter.

Over the years, I found that a 100 ppm N solution, applied weekly, seems to be a pretty good regimen for my plants under my conditions and media/growing techniques. However, now that I’m retired with a much less rigorous schedule to jump to, I find myself being a bit sloppy about that, and I can tell the plants are lagging. So, sometimes I’ll double the dose to compensate and I can see a real, positive response, so that suggests maybe I’ve been underfeeding, or at least, running the ragged edge with my irregular feeding.

A 100 ppm N K-Lite solution has a concentration of 0.74g/L or 740 ppm TDS (ignoring anything in the water), so when I double it I’m nearing a TDS of 1500 ppm, and have seen no issues, even for plants in S/H culture that are sitting the solution for a long time.

This is another one where I have heard both sides. My impression is that as long as pH is good your regimen works just fine. I am cautious with paph roots, maybe that is an old wives tale. I spoke to Jeff Morris who brings his Paph Mount Toro to the Paph forum each year with 17 spikes and he says he keeps fertilizer concentration for paphs below 400ppm. He does have 60ppm well water so that may help his plants too.

And to your earlier point re different kinds of fertilizer, I do find that paphs are little different than a lot of other orchids in that if the nutrients are wrong the plants grow glacially and look a little pale. A lot of other orchids seem to perk up if you throw any fertilizer at them and they’ll always make a new bulb each year. It may be a small one but compare that to paphs doing poorly that make like a leaf or two a year and do nothing. I know that’s not super scientific but there might be something to epiphytic vs terrestrial nutrition.

 

[gonewild]

So, sometimes I’ll double the dose to compensate and I can see a real, positive response,

Ray, after doubling the dose how soon do you see a positive results? I'm curious how quickly you see the plants react.

 

[Ray]

Ray, after doubling the dose how soon do you see a positive results? I'm curious how quickly you see the plants react.

Nothing is quick, but otherwise static plants start showing some activity within a few weeks.

I don’t think it’s a case of more food = instantaneous response, but more of the plants “feeling better” after enduring a period of starvation.

 

[Stone]

there might be something to epiphytic vs terrestrial nutrition.

There are 2 kinds of epiphytic orchids. The type which grow only on bark like Phalaenopsis or Vanda etc., and those which grow in accumulated leaf litter and humus like some paphs. Those on just bark must receive all the nutrients in balance including Ca, Mg and S just as you would for hydroponics and it must be continuous as there is nothing to ''hold'' a back-up supply.
Those epiphytes which grow in humus like lowii or parishii or villosum can be treated the same as the terrestrial kinds. Eg., Phrag besseae has been found growing in trees in moss and humus!