orchid Fertilizer question

[raybark]

Distilled water contains ZERO dissolved solids. Deionized (DI), which is water passed through a bed of resins that absorb minerals, is second only to distilled. Reverse osmosis (RO), which can give you water in the single-digit ppm dissolved-solids content is third. All are absolutely excellent for your plants.

Consider the fact that in nature, the only water our orchids see is either rain or dew, both of which are the condensation of evaporated water - distilled.

That water, when it cascades down through the forest canopy, picks up nutrients, but measurements have shown that to be in the realm of 15-25 ppm total dissolved solids (TDS), and that is only right when it first starts raining, dropping to nothing in a matter of a few seconds, as they are "washed" clean.

Considering the plants have evolved in that environment, it seems to make sense to treat them that way "in captivity". Accordingly, like others here, I use a complete fertilizer (as the water provides no nutrients at all) in RO water, and use it at only 30-35 ppm N. There is a calculator at my website that allows you to determine how much to use based upon your target ppm and the fertilizer formula. For example, I use a 13%N formula, so use only one teaspoon of it to make up 5 gallons of solution.

When using pure water, you have to be selective about your fertilizers and additives: Pure water, whether it is rainwater, distilled, deionized, or reverse osmosis, having no dissolved minerals, has little-to-no buffering (pH stabilizing) capacity, so the addition of chemicals to it may cause significant swings in the solution pH. Normal fertilizers will frequently result in an extremely acidic pH, so will require a manual pH adjustment. For simplicity, I use a complete fertilizer intended for use in pure, unbuffered water supplies - Geencare MSU RO formula or K-Lite.

OrchidAmor - stop waiting, "bite the bullet", and get an RO system. As Morris says, they are reliable and inexpensive to operate, and you will recoup your initial investment in no time. Locally, distilled or RO water at the drugstore is about $1/gallon. A top-of-the-line RO system will cost you about $0.04/gallon.

[Traci]

Thanks Steve, Annette , and Maurice. I will look into an RO machine. I had also been adjusting the fertilizer amount to 3 to 4 cups of water. I was really just trying to save some time which isn't worth it at the expense of my orchids. And besides my outdoor plants can use this dilute fertilizer too.

[citywildcat]

I'm glad this question came up. I acquired a few orchids that require only distilled water (okay, very "pure" water, a,k,a,. distilled). After awhile, I noticed that the water I used from the tap that has been allowed to sit on surfaces, whether it be the rack I set my dishes in after I wash them, places where it dripped from a jug that I put in the refrigerator, or where it was splashed underneath the cat's drinking fountain, THERE WAS A BUILD UP OF "SCUM" (FOR LACK OF A BETTER TERM). Some of it was downright nasty/I couldn't believe I was drinking that water myself! I found the place that sells the cheapest distilled water and started buying it there. I now use it for all of my orchids, regardless of whether it calls for it or not. Some get MSU minerals and super thrive EVERY OTHER WATERING (the ones that don't require distilled water). I find I am having much better luck than when I used the tapwater for those that didn't require distilled water. There seems to be fewer occurrences of "mysterious" leaf drops, yellow leaves, brown and black leaves, and even my "humidifier system" no longer has the telltale black spots when the filter needs to be replaced - I just replace it when it's scheduled. I'm sure it depends on where you live and the quality of your tap water, whether you have hard water, or city water. Each person must test their own water for themselves and make their own decision. This isn't anything anyone can advise you on, since no one knows what your water is like or the components of your water. DO WHAT WORKS BEST FOR YOU AND START OFF WITH THE BEST QUALITY WATER, WHATEVER THAT MAY BE (don't wait until you've lost a few plants like I did :-(

[raybark]

There is not a single orchid out there that requires distilled water without fertilizer, and if you continue that regimen, the plants will starve to death.

[citywildcat]

There is not a single orchid out there that requires distilled water without fertilizer, and if you continue that regimen, the plants will starve to death.

Perhaps I misspoke myself. I was talking about the water quality, excluding the fertilizer so I should have clarified that. They ALL get fertilizer. Some get DISTILLED water AND fertilizer (according to their particular schedule, whether it be "weakly weekly", weekly, every other watering, or another type of schedule/I have a spreadsheet) while other others get distilled water every other watering and distilled water with MSU minerals on the alternating waterings AND fertilizer (some get a little Superthrive thrown in at my discretion and/or Orchid Myst, also at my discretion.). I hope this clarifies it enough.

[raybark]

It certainly does, but I will add that all orchids will find advantage with pure water supplies and very dilute fertilizer applications, not just some.

In nature, orchids' only water sources are rain and dew/fog. They are, after all, "nature distilled". The nutrients that get washed down out of the forest canopy is maybe 15-25 ppm TDS, but that only lasts for a few seconds at the beginning of a downpour, dropping to zero thereafter. It seems to me that if the plants evolved to thrive under those conditions, I should try to approach that in my culture.

That's why I only use RO water, and add very small amounts of fertilizer (25 ppm N - likely 4-5x what is natural, but still a lot less than most folks apply) at every watering, roughly every other day or so. I also add a stimulant - KelpMax - about monthly.

[Missanna]

I know this is an old thread kind of, but I was growing orchids with tap water and I ended up with some "sudden" root death. My orchids had been declining for some time and I finally realized that it was because of the water. I checked the city water reports and found that my tap water is about 550ppm! So I bought an RO system. They seem expensive, but say you have four orchids that you paid $25 for, and your RO system is only 100$ (they are out there). If you let the plants slowly die and replace them (now you've spent 200$) you've spent the same amount you would have spent on the plants and RO system in the first place. NOW, if you have 30 orchids, or 50, the "price" of the RO system goes down dramatically. My orchids are so much happier now that I have been using RO for the last four years and because I don't make very much water, the filters and membrane last a long time. They are easy to install. Mine just runs from my cold water in a spare bathroom. I didn't install a special faucet and tank (tanks can waste a lot of water). Anyway, They seem complicated at first, but you can watch some videos online about them.

[citywildcat]

When I saw the scum that was in the water coming out of the tap and realized I would be drinking it, bathing in it, and giving it to my cats and plants, I wouldn't tolerate that.... well, there's nothing I can do about bathing in it but for everything else, I'm using the best water I can get. And yes, you may have to add back in some minerals but doing that on a periodic basis isn't a big deal. I'm glad your RO system has paid off for you!!

[Missanna]

So I assume you have a still? Does it take up a lot of space or is it a little one? I don't really know anything about stills and I've always been curious. In any case, I think it's been said, but you will need to use a fertilizer for pure water (also regular fertilizers can drop the ph below what is healthy for some orchids) and if you grow cattleyas you will also need extra calicium, so a cal/mag fertilizer in spring/summer will be needed. I think slippers need it too, but I don't grow those, so I can't say for sure.

[citywildcat]

So I assume you have a still? Does it take up a lot of space or is it a little one? I don't really know anything about stills and I've always been curious. In any case, I think it's been said, but you will need to use a fertilizer for pure water (also regular fertilizers can drop the ph below what is healthy for some orchids) and if you grow cattleyas you will also need extra calicium, so a cal/mag fertilizer in spring/summer will be needed. I think slippers need it too, but I don't grow those, so I can't say for sure.

Missanna, there's a place I get distilled water very cheap. **I should have mentioned, I have no Cattyleas or Paph's.** I buy it for my orchids and for drinking (me & my cats). So no, I don't have a still. But I try to remember that it is pure water without anything in it. The only things I add are MSU minerals, every other watering, EXCEPT those who need only distilled/pure water, sometimes Superthrive, and my fertilizer, as called for, individually, by orchid. (my choice of fertilizer is urea free by Grow More. I have 2 or 3 gizmos to measure the pH but I never use them