Fertilizer dilemma - Orchid Board

GoldStar135 · #1 07-17-2017, 09:24 AM

Hi everyone-
I have a little problem regarding fertilizer. My house uses water from a well, and therefore our water system relies on a water softener. I've been using the outdoor faucets because they bypass the softener, but however recently I found out that the water coming from the faucet is around 600ppm. With fertilizer (Miracle Gro orchid food) it's around 700ppm. Am I right in assuming that that amount is way too high for orchids? I have been seeing salt burns in the velamen of my phals.
I do have an RO system installed (9ppm), but I've hesitated in using it with my current fertilizer after learning that using fertilizer likely intended for tap water mixed with RO water could result in pH problems. I'm thinking of getting MSU fert for RO water, but that'll leave a bag of fertilizer left to waste. Is there any way I can make use of the unused fertilizer?

fishmom · #2 07-17-2017, 11:50 AM

Use it on your vegetables or other garden plants. There is nothing magic about orchid fertilizer, nutrients are nutrients, and your other plants will do just fine.

Roberta · #3 07-17-2017, 12:10 PM

Quote:

Originally Posted by GoldStar135

Hi everyone-
I have a little problem regarding fertilizer. My house uses water from a well, and therefore our water system relies on a water softener. I've been using the outdoor faucets because they bypass the softener, but however recently I found out that the water coming from the faucet is around 600ppm. With fertilizer (Miracle Gro orchid food) it's around 700ppm. Am I right in assuming that that amount is way too high for orchids? I have been seeing salt burns in the velamen of my phals.
I do have an RO system installed (9ppm), but I've hesitated in using it with my current fertilizer after learning that using fertilizer likely intended for tap water mixed with RO water could result in pH problems. I'm thinking of getting MSU fert for RO water, but that'll leave a bag of fertilizer left to waste. Is there any way I can make use of the unused fertilizer?

TDS is, indeed, a bit high for the orchids - some are more forgiving than others. Rather than getting yet another fertilizer (you may or may not have a pH problem with RO water and your regular fertilizer... you can't know unless you can test) you could just start with the RO, mix in 25% or so of the tap water, and you will have a nice TDS and plenty of buffering capacity to handle any acid tendency from the fertilizer. (The solution to pollution is dilution)

jkofferdahl · #4 07-17-2017, 12:14 PM

600PPM of what?

Dollythehun · #5 07-17-2017, 12:17 PM

Fishmom is right! I water my deck planters with leftover orchid water. The same planters in front of the garage get time release and water, period. The ones in back are much nicer, as are my patio tomatoes.
If you don't have a lot of orchids, you can filter your tap water in a filter pitcher. Our well is deep so the TDS isn't bad but, it has a lot of iron, the filter helps.

Roberta · #6 07-17-2017, 12:27 PM

Quote:

Originally Posted by jkofferdahl

600PPM of what?

It does make a difference... orchids can handle quite a bit of calcium (calcium carbonate), but if the TDS is heavy on sodium, the amount of tap water that might be blended in to use regular fertilizer should be smaller.

GoldStar135 · #7 07-18-2017, 08:09 AM

Quote:

Originally Posted by jkofferdahl

600PPM of what?

Since it's hard water I assume it's minerals like calcium/magnesium? I'm not 100% sure myself.
I'm not sure if it helps, but on spots on my phal's roots there is sometimes a thin white crust that flakes off easily if poked with something.

Roberta · #8 07-18-2017, 10:47 AM

Calcium carbonate or calcium sulfate I would expect. That's why you have a water softener indoors... replaces the calcium with sodium which is why the output is great in the shower but kills plants. So I think you would do fine just adding back a little tap water into the RO that you use for watering and fertilizing. No need to get fancier than that.

nogreenthumbs · #9 07-18-2017, 11:00 AM

Quote:

Originally Posted by Roberta

Calcium carbonate or calcium sulfate I would expect. That's why you have a water softener indoors... replaces the calcium with sodium which is why the output is great in the shower but kills plants. So I think you would do fine just adding back a little tap water into the RO that you use for watering and fertilizing. No need to get fancier than that.

The softened tap water with the sodium from inside the house or the unsoftened tap water without sodium from outside the house? I would assume the unsoftened.

If there's a TDS meter available, then maybe experiment to find an amount that gives some DS, but not too much, ie, 1 cup per gallon or something like that.

Roberta · #10 07-18-2017, 11:09 AM

Absolutely the unsoftened outside water. Don't use softened water on ANY plants. You can easily get an inexpensive TDS meter online, or at a hydroponics store (I suspect easier to find where I live than where you are) But for just a few orchids, don't stress on it. It takes very little for it to manage any acidity with fertilizer. A cup a gallon should be fine. (that's 1:16, so whatever the TDS is to start with, you end up with 1/16th as much, then you add in your fertilizer and go for it)